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Yu S, Ma L, Gao Y, Zheng H, Hu X, Liu R, Shi Y, Yin W. Effects of fissure length and angle on the fracture modes of 3D printed teeth model: Insights from DIC-based fracture tests and meshless numerical simulations. J Mech Behav Biomed Mater 2024; 154:106512. [PMID: 38554582 DOI: 10.1016/j.jmbbm.2024.106512] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2024] [Revised: 03/13/2024] [Accepted: 03/19/2024] [Indexed: 04/01/2024]
Abstract
To investigate the influences of teeth fissure properties on their failure modes, 3D Printing technology is used to prepare the teeth models. The strain distributions of the teeth model surfaces at each moment of the loading processes are obtained by the DIC technique. And the progressive failure processes as well as the stress distributions of the teeth models are simulated by the improved Smoothed Particle Hydrodynamics (SPH) Method. Experimental results show that under the action of the steel ball, the teeth models mainly produce two types of cracks: The tensile cracks along the pre-existing fissures and the shear cracks along both sides of the teeth model. The existence of prefabricated fissures greatly reduces the peak strength of the teeth models. Compared with the circumstances containing no pre-existing fissures, the peak strength of d = 1 cm, d = 2 cm and d = 3 cm decreases by 22.33%, 31.79% and 18.94%, respectively, and the peak strength of θ = 30°, θ = 45°, θ = 60° decreases by 10.78%, 44.01% and 34.3%, respectively. Numerical results show that the initiations of tensile cracks are induced by the high tensile stress concentrations at the pre-existing fissure tips, while the shear cracks are caused by the high tensile stress concentrations in the low tensile stress concentration areas after the initiation of tensile cracks. The research results can provide some references for the understandings of teeth failure mechanisms as well as the applications of SPH method into teeth crack propagation simulations.
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Affiliation(s)
- Shuyang Yu
- School of Transportation and Civil Engineering, Nantong University, Nantong, 226019, China
| | - Li Ma
- Nanjing Health Information Center, Nanjing, 210003, China
| | - Yuan Gao
- School of Transportation and Civil Engineering, Nantong University, Nantong, 226019, China
| | - Hao Zheng
- Nanjing Stomatological Hospital Medical School of Nanjing University, Nanjing, 210008, China
| | - Xueying Hu
- School of Transportation and Civil Engineering, Nantong University, Nantong, 226019, China
| | - Runyu Liu
- School of Transportation and Civil Engineering, Nantong University, Nantong, 226019, China
| | - Yue Shi
- School of Transportation and Civil Engineering, Nantong University, Nantong, 226019, China
| | - Weidong Yin
- Nanjing Health Information Center, Nanjing, 210003, China.
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Sabouri P, Hashemi A. Effect of loading direction and anatomical location on the ultimate tensile stress, fracture toughness, and failure patterns of knee meniscus. Knee 2024; 48:120-127. [PMID: 38579436 DOI: 10.1016/j.knee.2024.03.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2023] [Revised: 01/05/2024] [Accepted: 03/18/2024] [Indexed: 04/07/2024]
Abstract
BACKGROUND Rupture of the knee menisci is a common injury that can have implications for other conditions, such as osteoarthritis. The fracture toughness of soft tissue (Jc) is a mechanical property that characterizes its resistance to tear extension. To date, Jc of the meniscus has not been quantified. METHODS Cyclic tensile tests were conducted on meniscus samples to determine Jc and explore its characteristics. Initially, the study investigated the impact of an initial notch on the ultimate tensile stress. This allowed for an understanding of how the presence of a notch affects its structural integrity. Subsequently, Jc was measured in both the radial and circumferential directions to assess its loading direction dependency. Furthermore, the study assessed the effect of anatomical location by comparing samples collected from the femoral and tibial layers. RESULTS Defect tolerance of the meniscus is influenced by the loading direction. In the circumferential direction, the presence of an initial notch did not affect the ultimate stress, and no crack expansion was observed. In radial samples with a notch length of 40% or more of the total width, crack propagation occurred, leading to a decrease in the ultimate stress (p< 0.01). Additionally, Jc was found to be higher in the femoral layer compared to the tibial layer (p= 0.017). CONCLUSION The study also examined the failure patterns of the meniscus to enhance our understanding of its pathology. These insights contribute to a better comprehension of meniscus injuries and can aid in the development of more effective treatment strategies.
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Affiliation(s)
- Pouya Sabouri
- Biomechanical Engineering Group, Biomedical Engineering Department, Amirkabir University of Technology (Tehran Polytechnic), Tehran 15875-4413, Iran
| | - Ata Hashemi
- Biomechanical Engineering Group, Biomedical Engineering Department, Amirkabir University of Technology (Tehran Polytechnic), Tehran 15875-4413, Iran.
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Ananthasubramanian P, Sahay R, Raghavan N. Enhancement of the mechanical properties in ultra-low weight SWCNT sandwiched PDMS composites using a novel stacked architecture. Sci Rep 2024; 14:4487. [PMID: 38396000 PMCID: PMC10891152 DOI: 10.1038/s41598-024-54631-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Accepted: 02/14/2024] [Indexed: 02/25/2024] Open
Abstract
This study focuses on enhancing the mechanical properties of thin, soft, free-standing films via a layer-by-layer (LBL) fabrication process called LBL-FP. Soft polymer nanocomposite (PNC) thin films, combining polydimethylsiloxane (PDMS) and single-walled carbon nanotubes (SWCNT) at ultra-low loadings using a unique bottom-up LBL-FP, are examined. Two different structures of layered composites, (i) LBL PNCs- Layered composites with alternating layers of PDMS and SWCNT, (ii) Bulk PNCs- Layered composites with SWCNT dispersed in the bulk of PDMS, are comparatively investigated for their structural and mechanical properties. Silane-functionalized SWCNT strengthens the chemical bonding with PDMS, improving adhesion and dispersion. Mechanical analysis using nanoindentation, delamination, and dynamic analysis highlights the advantages of LBL PNCs with alternating layers of PDMS and SWCNT. Notably, LBL PNC (0.5 wt%) exhibits significant improvements, such as 2.6X increased nanoindentation resistance, 3X improved viscoelasticity, and (2-5)X enhanced tensile properties in comparison with neat PDMS. Due to this, LBL PNCs offer potential for soft, lightweight applications like wearables, electromagnetic interference shielding materials, and strain sensors while advancing composite thin film mechanics. The study emphasizes using a stacked architecture to produce PDMS-SWCNT multilayered PNCs with improved mechanics utilizing ultra-low concentrations of SWCNT. This first-of-its-kind stack design facilitates possibilities for lightweight composites utilizing less fillers. The LBL assembly involves the stacking of alternating layers of different materials, each contributing specific properties to enhance the overall strength and toughness of the structure.
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Affiliation(s)
- Pavithra Ananthasubramanian
- nano-Macro Reliability Laboratory (nMRL), Engineering Product Development (EPD) Pillar, Singapore University of Technology and Design, 8 Somapah Road, Singapore, 487372, Singapore
| | - Rahul Sahay
- nano-Macro Reliability Laboratory (nMRL), Engineering Product Development (EPD) Pillar, Singapore University of Technology and Design, 8 Somapah Road, Singapore, 487372, Singapore
| | - Nagarajan Raghavan
- nano-Macro Reliability Laboratory (nMRL), Engineering Product Development (EPD) Pillar, Singapore University of Technology and Design, 8 Somapah Road, Singapore, 487372, Singapore.
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Wang L, Liu Y, Wang S, Li J, Sun Y, Wang J, Zou Q. Research on ultrasonic bone cutting mechanism based on extended finite element method. Biomech Model Mechanobiol 2024:10.1007/s10237-023-01810-6. [PMID: 38261094 DOI: 10.1007/s10237-023-01810-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Accepted: 12/22/2023] [Indexed: 01/24/2024]
Abstract
The research on the crack propagation mechanism of bone has important research significance and clinical medical value for the selection of cutting parameters and the development of new surgical tools. In this paper, an extended finite element method (X-FEM) model of ultrasonic bone cutting considering microstructure was developed to further study the ultrasonic bone cutting mechanism and to quantitatively analyze the effects of cutting direction, ultrasonic parameters, and cutting parameters on the mechanism of ultrasonic bone cutting crack propagation. The results show that ultrasonic bone cutting is essentially a controlled crack propagation process, in which brittle crack and fatigue crack are the main crack propagation mechanisms. In order to improve the efficiency of ultrasonic bone cutting, large amplitude and high-frequency ultrasonic vibration are preferred. Compared with the other two cutting directions, the crack propagation deflection angle in the transverse cutting direction is the largest, resulting in the worst cutting surface. Therefore, in the path planning of orthopedic surgical robots, the transverse cutting direction should be avoided as much as possible. Frequency only has a significant effect on the crack propagation rate and has a positive correlation. There is a positive correlation between the deflection angle, propagation length, propagation rate, and amplitude, which provides the possibility to control the direction and length of crack propagation by controlling the amplitude of ultrasonic. The feed speed is much lower than the ultrasonic vibration speed, which makes the influence of ultrasonic vibration speed on the crack propagation characteristics dominant. The X-FEM model of ultrasonic bone cutting provides an effective method for selecting reasonable machining parameters of orthopedic robot and optimize the design of ultrasonic osteotome.
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Affiliation(s)
- Linwei Wang
- School of Mechanical Engineering and Automation, Northeastern University, Shenyang, 110819, China
| | - Yu Liu
- School of Mechanical Engineering and Automation, Northeastern University, Shenyang, 110819, China.
| | - Shiwei Wang
- School of Mechanical Engineering and Automation, Northeastern University, Shenyang, 110819, China
| | - Jinguang Li
- School of Mechanical Engineering and Automation, Northeastern University, Shenyang, 110819, China
| | - Yumeng Sun
- School of Mechanical Engineering and Automation, Northeastern University, Shenyang, 110819, China
| | - Jingyu Wang
- School of Mechanical Engineering and Automation, Northeastern University, Shenyang, 110819, China
| | - Qilei Zou
- School of Mechanical Engineering and Automation, Northeastern University, Shenyang, 110819, China
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Mubarak G, Gadala I, Barsoum I, AlFantazi A. Numerical investigation of the mechano-electro-chemical effect of X100 buried pipelines with pre-existing corrosion defects. Heliyon 2023; 9:e22440. [PMID: 38213594 PMCID: PMC10782170 DOI: 10.1016/j.heliyon.2023.e22440] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Revised: 10/18/2023] [Accepted: 11/13/2023] [Indexed: 01/13/2024] Open
Abstract
This study investigates the corrosion kinetics and crack propagation in buried transmission pipelines made of high-strength low alloy steel API X100. Despite its cost-effectiveness and ability to withstand high operating conditions without increasing pipe wall thickness, the corrosion kinetics in near-neutral pH environments for this steel grade is not fully understood. To address this gap, two numerical models were developed. The first model, using COMSOL Multiphysics v5.6, showed higher electrolyte potential at the corrosion defect center due to stress-induced defect growth, increasing corrosion susceptibility. The second model, employing the XFEM approach, evaluated crack initiation, propagation, and von Mises stress distribution along the crack path. This research contributes to a better understanding of corrosion and crack behavior in corroded pipelines, aiding in their performance improvement in near-neutral pH soil environments.
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Affiliation(s)
- Ghadeer Mubarak
- Department of Chemical Engineering, Khalifa University, Abu Dhabi, 12788, United Arab Emirates
| | - Ibrahim Gadala
- Center for Applied Research, NOVA Chemicals Corporation, 2928 16 St NE, Calgary, AB T2E 7K7, Canada
| | - Imad Barsoum
- Department of Mechanical Engineering, Khalifa University, Abu Dhabi, 12788, United Arab Emirates
- Advanced Digital & Additive Manufacturing Center, Khalifa University, Abu Dhabi, 12788, United Arab Emirates
| | - Akram AlFantazi
- Department of Chemical Engineering, Khalifa University, Abu Dhabi, 12788, United Arab Emirates
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Kolken H, Garcia AF, Plessis AD, Meynen A, Rans C, Scheys L, Mirzaali M, Zadpoor A. Mechanisms of fatigue crack initiation and propagation in auxetic meta-biomaterials. Acta Biomater 2022; 138:398-409. [PMID: 34763109 DOI: 10.1016/j.actbio.2021.11.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Revised: 10/29/2021] [Accepted: 11/02/2021] [Indexed: 01/16/2023]
Abstract
The fatigue performance of additively manufactured auxetic meta-biomaterials made from commercially pure titanium has been studied only recently. While certain assumptions have been made regarding the mechanisms underlying their fatigue failure, the exact mechanisms are not researched yet. Here, we studied the mechanisms of crack formation and propagation in cyclically loaded auxetic meta-biomaterials. Twelve different designs were subjected to compression-compression fatigue testing while performing full-field strain measurement using digital image correlation (DIC). The fatigue tests were stopped at different points before complete specimen failure to study the evolution of damage in the micro-architecture of the specimens using micro-computed tomography (micro-CT). Furthermore, finite element models were made to study the presence of stress concentrations. Structural weak spots were found in the inverted nodes and the vertical struts located along the outer rim of the specimens, matching the maximum principal strain concentrations and fracture sites in the DIC and micro-CT data. Cracks were often found to originate from internal void spaces or from sites susceptible to mode-I cracking. Many specimens maintained their structural integrity and exhibited no signs of rapid strain accumulation despite the presence of substantial crack growth. This observation underlines the importance of such microscale studies to identify accumulated damage that otherwise goes unnoticed. The potential release of powder particles from damaged lattices could elicit a foreign body response, adversely affecting the implant success. Finding the right failure criterion, therefore, requires more data than only those pertaining to macroscopic measurements and should always include damage assessment at the microscale. STATEMENT OF SIGNIFICANCE: The negative Poisson's ratio of auxetic meta-biomaterials makes them expand laterally in response to axial tension. This extraordinary property has great potential in the field of orthopedics, where it could enhance bone-implant contact. The fatigue performance of additively manufactured auxetic meta-biomaterials has only recently been studied and was found to be superior to many other bending- and stretch-dominated micro-architectures. In this study, we go beyond these macroscopic measurements and focus on the crack initiation and propagation. Full-field strain measurements and 3D imaging are used to paint a detailed picture of the mechanisms underlying fatigue. Using these data, specific aspects of the design and/or printing process can be targeted to improve the performance of auxetic meta-biomaterials in load-bearing applications.
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Maghami E, Josephson TO, Moore JP, Rezaee T, Freeman TA, Karim L, Najafi AR. Fracture behavior of human cortical bone: Role of advanced glycation end-products and microstructural features. J Biomech 2021; 125:110600. [PMID: 34246065 DOI: 10.1016/j.jbiomech.2021.110600] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2021] [Revised: 06/21/2021] [Accepted: 06/24/2021] [Indexed: 01/22/2023]
Abstract
Diabetes is associated with increased fracture risk in human bone, especially in the elderly population. In the present study, we investigate how simulated advanced glycation end-products (AGEs) and materials heterogeneity affect crack growth trajectory in human cortical bone. We used a phase field fracture framework on 2D models of cortical microstructure created from human tibias to analyze crack propagation. The increased AGEs level results in a higher rate of crack formation. The simulations also indicate that the mismatch between the fracture properties (e.g., critical energy release rate) of osteons and interstitial tissue can alter the post-yielding behavior. The results show that if the critical energy release rate of cement lines is lower than that of osteons and the surrounding interstitial matrix, cracks can be arrested by cement lines. Additionally, activation of toughening mechanisms such as crack merging and branching depends on bone microstructural morphology (i.e., osteons geometrical parameters, canals, and lacunae porosities). In conclusion, the present findings suggest that materials heterogeneity of microstructural features and the crack-microstructure interactions can play important roles in bone fragility.
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Affiliation(s)
- Ebrahim Maghami
- Department of Mechanical Engineering and Mechanics, Drexel University, Philadelphia, PA 19104, USA
| | - Timothy O Josephson
- Department of Mechanical Engineering and Mechanics, Drexel University, Philadelphia, PA 19104, USA
| | - Jason P Moore
- Department of Mechanical Engineering and Mechanics, Drexel University, Philadelphia, PA 19104, USA
| | - Taraneh Rezaee
- Department of Bioengineering, University of Massachusetts Dartmouth, 285 Old Westport Road, Dartmouth, MA 02747, USA
| | - Theresa A Freeman
- Thomas Jefferson University Division of Orthopaedic Research, Philadelphia, PA 19107, USA
| | - Lamya Karim
- Department of Bioengineering, University of Massachusetts Dartmouth, 285 Old Westport Road, Dartmouth, MA 02747, USA
| | - Ahmad R Najafi
- Department of Mechanical Engineering and Mechanics, Drexel University, Philadelphia, PA 19104, USA.
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Lin W, Liu P, Li S, Tian J, Cai W, Zhang X, Peng J, Miao C, Zhang H, Gu P, Wang Z, Zhang Z, Luo T. Multi-scale design of the chela of the hermit crab Coenobita brevimanus. Acta Biomater 2021; 127:229-41. [PMID: 33866037 DOI: 10.1016/j.actbio.2021.04.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2020] [Revised: 03/10/2021] [Accepted: 04/07/2021] [Indexed: 11/23/2022]
Abstract
The chela of the hermit crab protects its body against the attack from predators. Yet, a deep understanding of this mechanical defense is still lacking. Here, we investigate the chela of hermit crab, Coenobita brevimanus, and establish the relationships between the microstructures, chemical compositions and mechanical properties to gain insights into its biomechanical functions. We find that the chela is a multi-layered shell composed of five different layers with distinct features of the microstructures and chemical compositions, conferring different mechanical properties. Especially, an increase of the calcium carbonate content towards the layer furthest from the exterior, unlike the chemical gradients of many crustacean exoskeletons, provides a strong resistance to deformation. Nanoindentation measurements reveal that the overall gradient of the elastic modulus and hardness in the cross-section displays a sandwich profile, i.e., a soft core clamped by two stiff surface layers. Further mechanics modeling demonstrates that the high curvature and stiff innermost sublayer enhance the structural rigidity of the chela. In conjunction with the experimental observations, dynamic finite element analysis maps the time-spatial distribution of principal stress and indicates that fiber bridging might be the major mechanism against crack propagation at microscale. The lessons gained from the study of this multiphase biological composite could provide important insights into the design and fabrication of bioinspired materials for structural applications. STATEMENT OF SIGNIFICANCE: Multiple hierarchical structures have been discovered in a variety of exoskeletons. They are naturally designed to maintain the structural integrity and act as a protective layer for the animals. However, each kind of the hierarchical structures has its unique topology, chemical gradients as well as mechanical properties. We find that the chela is multi-layered shell composed of five different layers with distinct features of the microstructures and chemical compositions, conferring different mechanical properties. Especially, a large amount of helicoidal organic fibrils form highly organized 3D woven matrix in the innermost layer, providing a strong mechanical resistance to avoid catastrophic failure. The overall gradient of the elastic modulus and hardness in the cross-section display a sandwich profile, effectively minimizing the stress concentration and deformation. The lessons gained from the multiscale design strategy of the chela provide important insights into the design and fabrication of bioinspired materials.
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Chen X, Qian T, Hang F, Chen X. Water promotes the formation of fibril bridging in antler bone illuminated by in situ AFM testing. J Mech Behav Biomed Mater 2021; 120:104580. [PMID: 34015573 DOI: 10.1016/j.jmbbm.2021.104580] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Revised: 04/21/2021] [Accepted: 05/06/2021] [Indexed: 11/25/2022]
Abstract
Water, as one of the main components of bone, has a significant impact on the mechanical properties of bone. However, the micro-/nanoscale toughening mechanism induced by water in bone remains at only the theoretical level with static observations, and further research is still needed. In this study, a new in situ mechanical test combined with atomic force microscopy (AFM) was used to track the micro-/nanocrack propagation of hydrated and dehydrated antler bones in situ to explore the influence of water on the micro-/nanomechanical behavior of bone. In hydrated bone, observations of the crack tip region revealed major uncracked ligament bridging, and the conversion of mineralized collagen fibrils (MCFs) from bridging to breaking is clearly seen in real time. In dehydrated bone, multiple uncracked ligament bridges can be observed, but they are quickly broken by cracks, and the MCFs tend to break directly instead of forming fibril bridges. These experimental results indicate that the hydrated interface promotes slippage between collagen and the mineral phase and slippage between MCFs, while the dehydrated interface causes MCFs to fracture directly under lower strain. The platform we built provides new insights for studying the mechanism of toughening of the components in bones.
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Affiliation(s)
- Xiangxin Chen
- School of Materials Science and Engineering, South China University of Technology, Guangzhou, 510006, PR China; National Engineering Research Center for Tissue Restoration and Reconstruction, South China University of Technology, Guangzhou, 510006, PR China; Key Laboratory of Biomedical Engineering of Guangdong Province, South China University of Technology, Guangzhou, 510006, PR China; Key Laboratory of Biomedical Materials and Engineering of the Ministry of Education, South China University of Technology, Guangzhou, 510006, PR China; Innovation Center for Tissue Restoration and Reconstruction, South China University of Technology, Guangzhou, 510006, PR China
| | - Tianbao Qian
- School of Medicine, South China University of Technology, Guangzhou, 510006, PR China; National Engineering Research Center for Tissue Restoration and Reconstruction, South China University of Technology, Guangzhou, 510006, PR China; Key Laboratory of Biomedical Engineering of Guangdong Province, South China University of Technology, Guangzhou, 510006, PR China; Key Laboratory of Biomedical Materials and Engineering of the Ministry of Education, South China University of Technology, Guangzhou, 510006, PR China; Innovation Center for Tissue Restoration and Reconstruction, South China University of Technology, Guangzhou, 510006, PR China
| | - Fei Hang
- School of Materials Science and Engineering, South China University of Technology, Guangzhou, 510006, PR China; National Engineering Research Center for Tissue Restoration and Reconstruction, South China University of Technology, Guangzhou, 510006, PR China; Key Laboratory of Biomedical Engineering of Guangdong Province, South China University of Technology, Guangzhou, 510006, PR China; Key Laboratory of Biomedical Materials and Engineering of the Ministry of Education, South China University of Technology, Guangzhou, 510006, PR China; Innovation Center for Tissue Restoration and Reconstruction, South China University of Technology, Guangzhou, 510006, PR China.
| | - Xiaofeng Chen
- School of Materials Science and Engineering, South China University of Technology, Guangzhou, 510006, PR China; National Engineering Research Center for Tissue Restoration and Reconstruction, South China University of Technology, Guangzhou, 510006, PR China; Key Laboratory of Biomedical Engineering of Guangdong Province, South China University of Technology, Guangzhou, 510006, PR China; Key Laboratory of Biomedical Materials and Engineering of the Ministry of Education, South China University of Technology, Guangzhou, 510006, PR China; Innovation Center for Tissue Restoration and Reconstruction, South China University of Technology, Guangzhou, 510006, PR China.
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Han S, He C, Ma K, Yang Y. A study for lens capsule tearing during capsulotomy by finite element simulation. Comput Methods Programs Biomed 2021; 203:106025. [PMID: 33714899 DOI: 10.1016/j.cmpb.2021.106025] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Accepted: 02/24/2021] [Indexed: 06/12/2023]
Abstract
BACKGROUND AND OBJECTIVE During capsulotomy, the force applied to the anterior capsule is a crucial parameter controlling capsule tears, that affects the clinical performance. This study aims to investigate the tear force in capsulotomy and analyze the effects of different tearing conditions on the tear force. METHODS A three-dimensional model of the human lens was constructed based on published clinical data using the finite element (FE) method. The lens model consisted of four layers: the anterior and posterior lens capsule, the cortex, and the nucleus. Distortion energy failure criterion combined with the bilinear interface law was used to express the crack propagation process at the edge of the anterior lens capsule. At the clamping position, a local coordinate system was established to parameterize the capsule tearing. The simulation results were then validated by conducting a capsulorhexis experiment using isolated porcine eyes with force-sensing forceps. RESULTS The simulation results showed a good agreement with the experimental data of two porcine specimens (No. 6 and 9) during a stable tearing process (p-values = 0.76 and 0.10). The mean force differences between the experimental data and the simulation were 3.10 ± 2.24 mN and 2.14 ± 1.73 mN, respectively. The tear direction with a minimum mean tear force was at θ1 = 0° and θ2 = 30°. The tear velocity was not significantly different to the variation in the tear force. However, an appropriate capsulorhexis diameter was found to contribute to the reduction of tear force. CONCLUSIONS The outcome of this paper demonstrates that our FE model could be used in modeling lens capsule tearing and the theoretical study of tear mechanism.
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Affiliation(s)
- Shaofeng Han
- School of Mechanical Engineering & Automation, Beihang University, 100191, Beijing, China
| | - Changyan He
- School of Mechanical Engineering & Automation, Beihang University, 100191, Beijing, China
| | - Ke Ma
- Beijing Institute of Ophthalmology, Beijing TongRen Eye Center, Beijing TongRen Hospital, Capital Medical University, Beijing Ophthalmology and Visual Sciences Key Lab, 100730, Beijing, China
| | - Yang Yang
- School of Mechanical Engineering & Automation, Beihang University, 100191, Beijing, China.
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Kim SY, Kim BS, Kim H, Cho SY. Occlusal stress distribution and remaining crack propagation of a cracked tooth treated with different materials and designs: 3D finite element analysis. Dent Mater 2021; 37:731-740. [PMID: 33589271 DOI: 10.1016/j.dental.2021.01.020] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 10/19/2020] [Accepted: 01/20/2021] [Indexed: 11/26/2022]
Abstract
OBJECTIVE Here we used 3D finite element analysis (FEA) to analyze and directly compare stress distribution and crack propagation in identical cracked tooth models after treatment with various materials and designs. METHODS A 3D model of a cracked tooth was generated. We then applied eight restoration models, comprising combinations of three kinds of restoration designs (inlay, onlay, and crown) and four types of restoration materials (direct composite resin, indirect composite resin, ceramic, and gold). A 1000-N occlusal load was applied on the three reference points of the ball-shaped part in the direction of the longitudinal axis, causing crack line separation in the buccolingual direction. Stress distribution was analyzed on the occlusal surface, bottom level of the restoration, and mesiodistal longitudinal section. The stress on the lower margin of the crack surface was measured at 15 points on each model. RESULTS Ceramic inlay and onlay showed stress concentration at the restoration bottom, and low stress on the lower margin of the crack surface. Direct and indirect resin restorations exhibited low stress on the restoration bottom, and high stress on the proximal end of the lower margin of the crack surface. With a resin-unfilled gold crown, stress was concentrated on the crown bottom and the lower margin of the crack surface. Direct resin filling inside the gold crown yielded significantly decreased stress on both areas. SIGNIFICANCE Our results suggest that inlay and onlay ceramic restorations, and gold crown with resin filling inside, are advantageous methods for preventing further crack propagation.
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Affiliation(s)
- Sin-Young Kim
- Department of Conservative Dentistry, Seoul St. Mary's Dental Hospital, College of Medicine, The Catholic University of Korea, 222 Banpo-daero, Seocho-gu, Seoul 06591, Republic of Korea.
| | - Ban-Suk Kim
- Department of Conservative Dentistry, Seoul St. Mary's Dental Hospital, College of Medicine, The Catholic University of Korea, 222 Banpo-daero, Seocho-gu, Seoul 06591, Republic of Korea.
| | - Hakjin Kim
- Convert., Ltd., Suite 705, Bodeumgwan, Kangwon National University, Chuncheon-si, Gangwon-do 24341, Republic of Korea.
| | - Sin-Yeon Cho
- Department of Conservative Dentistry, National Health Insurance Service Ilsan Hospital, 100, Ilsan-ro, Ilsandong-gu, Goyang-si, Gyeonggi-do 10444, Republic of Korea.
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Sabouri P, Hashemi A. Influence of crack length and anatomical location on the fracture toughness of annulus fibrosus. Med Eng Phys 2021; 88:1-8. [PMID: 33485508 DOI: 10.1016/j.medengphy.2020.11.013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Revised: 10/16/2020] [Accepted: 11/21/2020] [Indexed: 01/07/2023]
Abstract
Fracture toughness (Jc) of a soft biological tissue is an important mechanical property that characterizes its resistance to crack or tear extension. To date, no information is available on fracture toughness of annulus fibrosus (AF); therefore, its defect tolerance is not known. The present study modified a previously introduced method to determine Jc of ovine AF. Then, the effect of the notch length on the failure pattern and Jc was investigated. Also, the test samples of anterior and lateral regions were collected to determine the effect of the location on Jc. Results showed that for a notch length of less than 45% of total width, no crack extension occurred, but for a notch length above 45% of the width, crack propagation and ultimately the failure of the AF were observed. However, statistical analysis indicated no significant difference on Jc (p = 0.5) for the initial notch length of 50% and 70% of total width. The fracture toughness was significantly higher for the samples extracted from the lateral site than those from the anterior site (p < 0.05). Dissimilar failure patterns were observed for different initial notch lengths. Among the parameters studied, the defect tolerance of AF was dependent on the initial tear size.
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Affiliation(s)
- Pouya Sabouri
- Biomechanical Engineering Group, Biomedical Engineering Department, Amirkabir University of Technology (Tehran Polytechnic), Tehran 15875-4413, Iran
| | - Ata Hashemi
- Biomechanical Engineering Group, Biomedical Engineering Department, Amirkabir University of Technology (Tehran Polytechnic), Tehran 15875-4413, Iran.
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13
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Gustafsson A, Tognini M, Bengtsson F, Gasser TC, Isaksson H, Grassi L. Subject-specific FE models of the human femur predict fracture path and bone strength under single-leg-stance loading. J Mech Behav Biomed Mater 2021; 113:104118. [PMID: 33125949 DOI: 10.1016/j.jmbbm.2020.104118] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Revised: 08/25/2020] [Accepted: 09/24/2020] [Indexed: 12/16/2022]
Abstract
Hip fractures are a major health problem with high socio-economic costs. Subject-specific finite element (FE) models have been suggested to improve the fracture risk assessment, as compared to clinical tools based on areal bone mineral density, by adding an estimate of bone strength. Typically, such FE models are limited to estimate bone strength and possibly the fracture onset, but do not model the fracture process itself. The aim of this study was to use a discrete damage approach to simulate the full fracture process in subject-specific femur models under stance loading conditions. A framework based on the partition of unity finite element method (PUFEM), also known as XFEM, was used. An existing PUFEM framework previously used on a homogeneous generic femur model was extended to include a heterogeneous material description together with a strain-based criterion for crack initiation. The model was tested on two femurs, previously mechanically tested in vitro. Our results illustrate the importance of implementing a subject-specific material distribution to capture the experimental fracture pattern under stance loading. Our models accurately predicted the fracture pattern and bone strength (1% and 5% error) in both investigated femurs. This is the first study to simulate complete fracture paths in subject-specific FE femur models and it demonstrated how discrete damage models can provide a more complete picture of fracture risk by considering both bone strength and fracture toughness in a subject-specific fashion.
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Yamaguchi S, Katsumoto Y, Hayashi K, Aoki M, Kunikata M, Nakase Y, Lee C, Imazato S. Fracture origin and crack propagation of CAD/CAM composite crowns by combining of in vitro and in silico approaches. J Mech Behav Biomed Mater 2020; 112:104083. [PMID: 32979609 DOI: 10.1016/j.jmbbm.2020.104083] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Revised: 09/04/2020] [Accepted: 09/07/2020] [Indexed: 12/18/2022]
Abstract
PURPOSE Fractographic analysis has been used to investigate the fracture behavior of Computer-aided design/computer-aided manufacturing (CAD/CAM) composite crowns by subjecting them to compression tests. However, it is difficult to investigate details of the fracture, including its initiation and propagation, using in vitro tests. The aim of this study was to determine the fracture origins and the order of crack initiation of CAD/CAM composite crowns using in silico nonlinear dynamic finite element analysis (FEA). MATERIAL AND METHODS The following materials were used: Cerasmart (CS), Katana Avencia Block (KA), and Shofu Block HC (HC) as CAD/CAM crowns, Panavia SA Cement Plus (SA) as a luting material, and Clearfil DC Core Plus (DC) as an abutment. The elastic moduli and fracture strain of each material were obtained from the stress-strain curve of in vitro three-point bending tests. The fracture origins and order of crack initiation of the materials were determined by in silico nonlinear dynamic compression analysis. Load-displacement curves were statistically compared with the results of the in vitro compression tests (Pearson's correlation test, α = 0.05). RESULTS The nonlinear dynamic FEA demonstrated that crack initiation was primarily observed near the lingual side of the CAD/CAM crowns and immediately propagated to the central fossa. The models were fractured following the in vitro fracture strains, showing the same order for the products tested (CS/KA/HC, SA, and DC). Load-displacement curves with the use of CS, KA, and HC were significantly correlated to the corresponding in vitro compression tests results (CS: r = 0.985, p < 0.05, KA: r = 0.987, p < 0.05, and HC: r = 0.997, p < 0.05). CONCLUSIONS The in silico model established in this study clarified the crack initiation of the CAD/CAM composite crowns and the order of crack initiation among the investigated products, suggesting that the present approach is useful for analyzing the fracture behavior of CAD/CAM composite crowns in detail.
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Affiliation(s)
- Satoshi Yamaguchi
- Department of Biomaterials Science, Osaka University Graduate School of Dentistry, 1-8 Yamadaoka, Suita, Osaka, 565-0871, Japan.
| | - Yu Katsumoto
- Department of Biomaterials Science, Osaka University Graduate School of Dentistry, 1-8 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Kimiko Hayashi
- Department of Biomaterials Science, Osaka University Graduate School of Dentistry, 1-8 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Maika Aoki
- Department of Biomaterials Science, Osaka University Graduate School of Dentistry, 1-8 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Miwa Kunikata
- Department of Biomaterials Science, Osaka University Graduate School of Dentistry, 1-8 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Yutaro Nakase
- Department of Biomaterials Science, Osaka University Graduate School of Dentistry, 1-8 Yamadaoka, Suita, Osaka, 565-0871, Japan; Department of Pediatric Dentistry, Osaka University Graduate School of Dentistry, 1-8 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Chunwoo Lee
- Department of Biomaterials Science, Osaka University Graduate School of Dentistry, 1-8 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Satoshi Imazato
- Department of Biomaterials Science, Osaka University Graduate School of Dentistry, 1-8 Yamadaoka, Suita, Osaka, 565-0871, Japan; Department of Advanced Functional Biomaterials Science, Osaka University Graduate School of Dentistry, 1-8 Yamadaoka, Suita, Osaka, 565-0871, Japan
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15
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Wu D, Pujari-Palmer M, Bojan A, Palmquist A, Procter P, Öhman-Mägi C, Ferguson SJ, Isaksson P, Persson C. The effect of two types of resorbable augmentation materials - a cement and an adhesive - on the screw pullout pullout resistance in human trabecular bone. J Mech Behav Biomed Mater 2020; 110:103897. [PMID: 32957202 DOI: 10.1016/j.jmbbm.2020.103897] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Revised: 05/18/2020] [Accepted: 05/30/2020] [Indexed: 11/29/2022]
Abstract
Augmentation materials, such as ceramic and polymeric bone cements, have been frequently used to improve the physical engagement of screws inserted into bone. While ceramic, degradable cements may ultimately improve fixation stability, reports regarding their effect on early fixation stability have been inconsistent. On the other hand, a newly developed degradable ceramic adhesive that can bond with tissues surrounding the screw, may improve the pullout performance, ensure early stability, and subsequent bony integration. The aim of this study was to investigate failure mechanisms of screw/trabecular bone constructs by comparing non-augmented screws with screws augmented with a calcium phosphate cement or an adhesive, i.e. a phosphoserine-modified calcium phosphate. Pullout tests were performed on screws inserted into trabecular cylinders extracted from human femoral bone. Continuous and stepwise pullout loading was applied with and without real-time imaging in a synchrotron radiation micro-computed tomograph, respectively. Statistical analysis that took the bone morphology into account confirmed that augmentation with the adhesive supported significantly higher pullout loads compared to cement-augmented, or non-augmented screws. However, the adhesive also allowed for a higher injection volume compared to the cement. In-situ imaging showed cracks in the vicinity of the screw threads in all groups, and detachment of the augmentation materials from the trabecular bone in the augmented specimens. Additional cracks at the periphery of the augmentation and the bone-material interfaces were only observed in the adhesive-augmented specimen, indicating a contribution of surface bonding to the pullout resistance. An adhesive that has potential for bonding with tissues, displayed superior pullout resistance, compared to a brushite cement, and may be a promising material for cementation or augmentation of implants.
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Affiliation(s)
- Dan Wu
- Department of Materials Science and Engineering, Uppsala University, Sweden.
| | | | - Alicja Bojan
- Department of Orthopaedics, Sahlgrenska University Hospital Gothenburg, Sweden
| | | | - Philip Procter
- Department of Materials Science and Engineering, Uppsala University, Sweden
| | | | | | - Per Isaksson
- Department of Materials Science and Engineering, Uppsala University, Sweden
| | - Cecilia Persson
- Department of Materials Science and Engineering, Uppsala University, Sweden
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Wiedenmann F, Becker F, Eichberger M, Stawarczyk B. Measuring the polymerization stress of self-adhesive resin composite cements by crack propagation. Clin Oral Investig 2020; 25:1011-1018. [PMID: 32556662 PMCID: PMC7878217 DOI: 10.1007/s00784-020-03391-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Accepted: 06/03/2020] [Indexed: 11/30/2022]
Abstract
Objectives To test the polymerization stress of nine self-adhesive resin composite cements (G-CEM, iCEM, Bifix SE, Maxcem Elite, PANAVIA SA, SoloCem, SmartCem 2, SpeedCEM, RelyX Unicem 2) and one glass ionomer cement (control group; Ketac Cem). Materials and methods The crack propagation of a feldspar ceramic (n = 130) was determined by measuring crack lengths that originated from Vickers indentations, prior to and after the application and polymerization of the self-adhesive resin cements. Results for crack propagation were converted to polymerization stress values, and statistical analysis was performed using one-way ANOVA followed by Scheffé post hoc test. Results SmartCem 2 presented higher stress values than iCEM, SoloCem, and Ketac Cem, while Ketac Cem showed lower values than Bifix SE, Maxcem Elite, SmartCem 2, SpeedCEM, and RelyX Unicem 2. Conclusions Self-adhesive resin composite cements differ in their polymerization stress, which may affect the durability of the restoration. For restorations made from ceramics with lower flexural strength, such as feldspar ceramics, resin composite cement materials with less polymerization stress should be preferred. Clinical Relevance As a high polymerization shrinkage may increase crack propagation, the determination of the polymerization stress of self-adhesive resin composite cements employed for fixing all-ceramic restorations is an important factor.
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Affiliation(s)
- Felicitas Wiedenmann
- Department of Prosthetic Dentistry, University Hospital of Munich (LMU), Goethestraße 70, 80336, Munich, Germany.
| | - Fabian Becker
- Department of Prosthetic Dentistry, University Hospital of Munich (LMU), Goethestraße 70, 80336, Munich, Germany
| | - Marlis Eichberger
- Department of Prosthetic Dentistry, University Hospital of Munich (LMU), Goethestraße 70, 80336, Munich, Germany
| | - Bogna Stawarczyk
- Department of Prosthetic Dentistry, University Hospital of Munich (LMU), Goethestraße 70, 80336, Munich, Germany
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17
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Terzano M, Dini D, Rodriguez Y Baena F, Spagnoli A, Oldfield M. An adaptive finite element model for steerable needles. Biomech Model Mechanobiol 2020; 19:1809-1825. [PMID: 32152795 PMCID: PMC7502456 DOI: 10.1007/s10237-020-01310-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Accepted: 02/17/2020] [Indexed: 11/28/2022]
Abstract
Penetration of a flexible and steerable needle into a soft target material is a complex problem to be modelled, involving several mechanical challenges. In the present paper, an adaptive finite element algorithm is developed to simulate the penetration of a steerable needle in brain-like gelatine material, where the penetration path is not predetermined. The geometry of the needle tip induces asymmetric tractions along the tool–substrate frictional interfaces, generating a bending action on the needle in addition to combined normal and shear loading in the region where fracture takes place during penetration. The fracture process is described by a cohesive zone model, and the direction of crack propagation is determined by the distribution of strain energy density in the tissue surrounding the tip. Simulation results of deep needle penetration for a programmable bevel-tip needle design, where steering can be controlled by changing the offset between interlocked needle segments, are mainly discussed in terms of penetration force versus displacement along with a detailed description of the needle tip trajectories. It is shown that such results are strongly dependent on the relative stiffness of needle and tissue and on the tip offset. The simulated relationship between programmable bevel offset and needle curvature is found to be approximately linear, confirming empirical results derived experimentally in a previous work. The proposed model enables a detailed analysis of the tool–tissue interactions during needle penetration, providing a reliable means to optimise the design of surgical catheters and aid pre-operative planning.
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Affiliation(s)
- Michele Terzano
- Department of Engineering and Architecture, University of Parma, Parco Area delle Scienze 181/A, 43124, Parma, Italy
| | - Daniele Dini
- Department of Mechanical Engineering, Imperial College London, Exhibition Road, London, SW7 2AZ, UK.
| | | | - Andrea Spagnoli
- Department of Engineering and Architecture, University of Parma, Parco Area delle Scienze 181/A, 43124, Parma, Italy
| | - Matthew Oldfield
- Department of Mechanical Engineering Sciences, University of Surrey, Guildford, Surrey, GU2 7XH, UK
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18
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Wang B, Zhou B, Zhang X, Wang B. Microstructure and mechanical properties of an alpha keratin bovine hoof wall. J Mech Behav Biomed Mater 2020; 104:103689. [PMID: 32174434 DOI: 10.1016/j.jmbbm.2020.103689] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2019] [Revised: 01/22/2020] [Accepted: 02/07/2020] [Indexed: 11/17/2022]
Abstract
Bovine hoof wall with an alpha keratin structure, as the interface between the ground and the body, can protect the bony skeleton from the impact and the destruction. Microstructure and mechanical properties of the bovine hoof wall are investigated by scanning electron microscope (SEM), transmission electron microscope (TEM) and quasi-static mechanical tests. Mechanical results show that the mean J-integral values of the LD specimens parallel to the tubular axis are higher than those of the TD specimens normal to the tubular axis, and the fracture toughness reaches the peak values (21 kJ/m2, 33 kJ/m2 for the TD and the LD specimens, respectively) at 16.5% moisture content. The morphology results show that the laminated keratin structure can form the extensive strain-transition interfaces and the tubules played an important role in twisting crack propagation. Angles of the laminated structures within the inter-tubular materials are not a uniform distribution varying from 0° to 90° against to the tubular axis. The interlocking interface in the tubular structure can provide increased the contact area and contribute to the bonding strength between the layers. We also propose models to illustrate the morphological structure and the crack propagation mechanism of the bovine hoof wall. This structure with the strong fracture resistance ability will provide a new inspiration for design of structural materials and architectures.
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Affiliation(s)
- Bingfeng Wang
- State Key Laboratory for Powder Metallurgy, Central South University, Changsha, 410083, Hunan, People's Republic of China; School of Materials Science and Engineering, Central South University, Changsha, 410083, People's Republic of China.
| | - Bingqing Zhou
- School of Materials Science and Engineering, Central South University, Changsha, 410083, People's Republic of China
| | - Xiaoyong Zhang
- State Key Laboratory for Powder Metallurgy, Central South University, Changsha, 410083, Hunan, People's Republic of China
| | - Bin Wang
- Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518000, People's Republic of China
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19
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Bai W, Shu L, Sun R, Xu J, Silberschmidt VV, Sugita N. Mechanism of material removal in orthogonal cutting of cortical bone. J Mech Behav Biomed Mater 2020; 104:103618. [PMID: 31929098 DOI: 10.1016/j.jmbbm.2020.103618] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Revised: 12/14/2019] [Accepted: 01/03/2020] [Indexed: 11/19/2022]
Abstract
ANALYSIS of a mechanism of bone cutting has an important theoretical and practical significance for orthopaedic surgeries. In this study, the mechanism of material removal in orthogonal cutting of cortical bone is investigated. Chip morphology and crack propagation in cortical bone for various cutting directions and depth-of-cut (DOC) levels are analysed, with consideration of microstructural and sub-microstructural features and material anisotropy. Effects of different material properties of osteons, interstitial matrix and cement lines on chip morphology and crack propagation are elucidated for different cutting directions. This study revealed that differences in chip morphology for various DOCs were due to comparable sizes of the osteons, lamellae and DOC. Acquired force signals and recorded high-speed videos revealed the reasons of fluctuations of dynamic components in tests. Meanwhile, a frequency-domain analysis of force signals showed a frequency difference between formation of a bulk fractured chip and small debris for different cutting directions. In addition, SEM images of the top and side surfaces of the machined bone were obtained. Thus, the analysis of the cutting force and surface damage validated the character of chip formation and explained the material-removal mechanism. This study reveals the mechanism of chip formation in the orthogonal cutting of the cortical bone, demonstrating importance of the correlation between the chip morphologies, the depth of cut and the microstructure and sub-microstructure of the cortical bone. For the first time, it assessed the fluctuations of cutting forces, accompanying chip formation, in time and frequency domains. These findings provide fundamental information important for analysis of cutting-induced damage of the bone tissue, optimization of the cutting process and clinical applications of orthopaedic instruments.
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Affiliation(s)
- Wei Bai
- State Key Lab of Digital Manufacturing Equipment and Technology, Huazhong University of Science and Technology, Wuhan, 430074, China; Department of Mechanical Engineering, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 1138656, Japan.
| | - Liming Shu
- Department of Mechanical Engineering, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 1138656, Japan.
| | - Ronglei Sun
- State Key Lab of Digital Manufacturing Equipment and Technology, Huazhong University of Science and Technology, Wuhan, 430074, China.
| | - Jianfeng Xu
- State Key Lab of Digital Manufacturing Equipment and Technology, Huazhong University of Science and Technology, Wuhan, 430074, China.
| | - Vadim V Silberschmidt
- Wolfson School of Mechanical, Electrical and Manufacturing Engineering, Loughborough University, Leicestershire, LE11 3TU, UK.
| | - Naohiko Sugita
- Department of Mechanical Engineering, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 1138656, Japan.
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Karimi A, Razaghi R, Koyama M. A patient-specific numerical modeling of the spontaneous coronary artery dissection in relation to atherosclerosis. Comput Methods Programs Biomed 2019; 182:105060. [PMID: 31514089 DOI: 10.1016/j.cmpb.2019.105060] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Revised: 08/28/2019] [Accepted: 08/31/2019] [Indexed: 06/10/2023]
Abstract
The spontaneous coronary artery dissection (SCAD) is a clinical complication of angioplasty leading to an initiation of a tear/crack in the intima layer of the artery. The crack can propagate to the interface of the intima-media layer following by intramural hematoma. The relation between the SCAD and atherosclerosis is a controversial issue, as some studies stated no correlation between them while others showed that a crack can initiate in the intima but cannot propagate into the atrophied media layer. To investigate the relation between the intraluminal crack propagation in the atherosclerotic artery and SCAD, this study numerically investigated the initiation and propagation of a crack in the intraluminal and radial locations of the healthy and atherosclerotic human coronary arterial walls. The energy release rate, namely J-integral, is computed as a numerical derivative of the strain energy with respect to a crack extension using a user-defined virtual crack method (VCE) of extended finite element method (XFEM). Experimental measurements were carried out to calculate the elasto-plastic mechanical properties of the healthy and atherosclerotic human coronary arteries. The experimental data were then assigned to our own established patient-specific FE model of the coronary artery. Cracks were sketched in the intraluminal and radial locations of the arterial wall and allowed to propagate to the virtual interface of the intima-media to form a false lumen. The results revealed a higher stress at the crack tip of the healthy arterial wall compared to the atherosclerotic one. Lower crack tip opening displacement (CTOD) and crack tip opening angle (CTOA) were observed in the intraluminal crack of the atherosclerotic artery. J-integral of the atherosclerotic arterial wall was also found to be higher than the healthy one at the intraluminal crack. The results revealed that although a crack can initiate in the intraluminal of an atherosclerotic artery, it cannot propagate into the media layer due to a relatively higher rate of the strain energy release in the atherosclerotic arterial wall compared to the healthy one.
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Affiliation(s)
- Alireza Karimi
- Department of Mechanical Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan.
| | - Reza Razaghi
- Research Department, Heel of Scene Ltd., Fukuoka, Japan
| | - Motomichi Koyama
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan.
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21
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Hosaka K, Tichy A, Ikeda M, Nakagawa K, Sadr A, Tagami J, Takahashi M, Sato K, Nishitani Y, Klein-Junior CA, Pashley DH, Nakajima M. Ultra-high-speed videography of resin-dentin interface failure dynamics under tensile load. Dent Mater 2019; 35:e153-e161. [PMID: 31078308 DOI: 10.1016/j.dental.2019.04.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2018] [Revised: 03/17/2019] [Accepted: 04/12/2019] [Indexed: 10/26/2022]
Abstract
OBJECTIVES Ultra-high-speed (UHS) videography was used to visualize the fracture phenomena at the resin-dentin interface during micro-tensile bond strength (μTBS) test. We also investigated whether UHS videography is applicable for failure-mode analysis. METHODS Ten human mid-coronal dentin surfaces were bonded using Clearfil SE Bond either in self-etching (SE) or etch-and-rinse (ER) mode. After 24-h water storage, the samples were cut into beams for μTBS test and tested at a cross-head speed of 1 mm/min. The fracture phenomena at the bonded interface were captured using a complementary metal-oxide-semiconductor digital UHS camera at 299,166 frames per second. The failure modes were classified using UHS videography, followed by scanning electron microscopy (SEM) analysis. The failure-mode distributions determined by UHS videography and SEM analysis were statistically analyzed using Fisher's exact test with Bonferroni correction. RESULTS The crack-propagation speed exceeded 1,500 km/h. No significant difference was found between the SEM and UHS videography failure-mode distributions in the SE mode. A significant difference appeared between them in the ER mode. Significant differences in the incidence of cohesive failures within the adhesive and at the adhesive-composite interface between the SE and ER modes were identified by both SEM and UHS videography. SIGNIFICANCE UHS videography enabled visualization of the fracture dynamics at the resin- dentin interfaces under tensile load. However, the resolution at such high frame rate was insufficient to classify the failure mode as precisely as that of SEM. Nevertheless, UHS videography can provide more detailed information about the fracture origin and propagation.
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Affiliation(s)
- Keiichi Hosaka
- Department of Cariology and Operative Dentistry, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan.
| | - Antonin Tichy
- Department of Cariology and Operative Dentistry, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan; Institute of Dental Medicine, First Faculty of Medicine of the Charles University and General University Hospital in Prague, Karlovo namesti 32, Prague, 121 11, Czech Republic
| | - Masaomi Ikeda
- Department of Oral Prosthetic Engineering, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan
| | - Keiichi Nakagawa
- Department Bioengineering, Department of Precision Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan
| | - Alireza Sadr
- Department of Restorative Dentistry, School of Dentistry, University of Washington, 1959 NE Pacific Street, Seattle, Washington, 98195-7456, USA
| | - Junji Tagami
- Department of Cariology and Operative Dentistry, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan
| | - Masahiro Takahashi
- Department of Cariology and Operative Dentistry, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan
| | - Kento Sato
- Department of Cariology and Operative Dentistry, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan
| | - Yoshihiro Nishitani
- Department of Operative Dentistry, Kagoshima University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 2-5-1 Shikata-cho, Kita-ku, Okayama 700-8525, Japan
| | - Celso Afonso Klein-Junior
- Department of Operative Dentistry, School of Dentistry, Lutheran University of Brazil, Avenue Martinho Lutero, 301. CEP96501-595. Cachoeira do Sul, Rs, Brazil
| | - David H Pashley
- Department of Oral Biology, College of Dental Medicine, Georgia Regents University, 1120 15th Street, CL-2112, Augusta, Georgia, 30912-1129, USA
| | - Masatoshi Nakajima
- Department of Cariology and Operative Dentistry, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan
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22
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Kim K, Yoon JC, Kim J, Kim JH, Lee SW, Yoon A, Lee Z. Dedicated preparation for in situ transmission electron microscope tensile testing of exfoliated graphene. Appl Microsc 2019; 49:3. [PMID: 33580404 PMCID: PMC7818284 DOI: 10.1007/s42649-019-0005-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Accepted: 02/12/2019] [Indexed: 12/02/2022] Open
Abstract
Graphene, which is one of the most promising materials for its state-of-the-art applications, has received extensive attention because of its superior mechanical properties. However, there is little experimental evidence related to the mechanical properties of graphene at the atomic level because of the challenges associated with transferring atomically-thin two-dimensional (2D) materials onto microelectromechanical systems (MEMS) devices. In this study, we show successful dry transfer with a gel material of a stable, clean, and free-standing exfoliated graphene film onto a push-to-pull (PTP) device, which is a MEMS device used for uniaxial tensile testing in in situ transmission electron microscopy (TEM). Through the results of optical microscopy, Raman spectroscopy, and TEM, we demonstrate high quality exfoliated graphene on the PTP device. Finally, the stress-strain results corresponding to propagating cracks in folded graphene were simultaneously obtained during the tensile tests in TEM. The zigzag and armchair edges of graphene confirmed that the fracture occurred in association with the hexagonal lattice structure of graphene while the tensile testing. In the wake of the results, we envision the dedicated preparation and in situ TEM tensile experiments advance the understanding of the relationship between the mechanical properties and structural characteristics of 2D materials.
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Affiliation(s)
- Kangsik Kim
- School Materials Science and Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan Metropolitan City, 44919 Republic of Korea
| | - Jong Chan Yoon
- School Materials Science and Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan Metropolitan City, 44919 Republic of Korea
| | - Jaemin Kim
- School Materials Science and Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan Metropolitan City, 44919 Republic of Korea
| | - Jung Hwa Kim
- School Materials Science and Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan Metropolitan City, 44919 Republic of Korea
| | - Suk Woo Lee
- School Materials Science and Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan Metropolitan City, 44919 Republic of Korea
| | - Aram Yoon
- School Materials Science and Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan Metropolitan City, 44919 Republic of Korea
| | - Zonghoon Lee
- School Materials Science and Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan Metropolitan City, 44919 Republic of Korea
- Center for Multidimensional Carbon Materials, Institute for Basic Science (IBS), Ulsan Metropolitan City, 44919 Republic of Korea
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Jiang Y, Liang X, Guo M, Cao Y, Cai S. Fracture mechanics modeling of popping event during daughter cell separation. Biomech Model Mechanobiol 2018; 17:1131-1137. [PMID: 29748837 DOI: 10.1007/s10237-018-1019-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Accepted: 04/23/2018] [Indexed: 10/16/2022]
Abstract
Most bacteria cells divide by binary fission which is part of a bacteria cell cycle and requires tight regulations and precise coordination. Fast separation of Staphylococcus Aureus (S. Aureus) daughter cells, named as popping event, has been observed in recent experiments. The popping event was proposed to be driven by mechanical crack propagation in the peripheral ring which connected two daughter cells before their separation. It has also been shown that after the fast separation, a small portion of the peripheral ring was left as a hinge. In the article, we develop a fracture mechanics model for the crack growth in the peripheral ring during S. Aureus daughter cell separation. In particular, using finite element analysis, we calculate the energy release rate associated with the crack growth in the peripheral ring, when daughter cells are inflated by a uniform turgor pressure inside. Our results show that with a fixed inflation of daughter cells, the energy release rate depends on the crack length non-monotonically. The energy release rate reaches a maximum value for a crack of an intermediate length. The non-monotonic relationship between the energy release rate and crack length clearly indicates that the crack propagation in the peripheral ring can be unstable. The computed energy release rate as a function of crack length can also be used to explain the existence of a small portion of peripheral ring remained as hinge after the popping event.
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Affiliation(s)
- Yuxuan Jiang
- Department of Mechanical and Aerospace Engineering, University of California, San Diego, La Jolla, CA, 92093, USA
- Department of Engineering Mechanics, Institute of Biomechanics and Medical Engineering, Tsinghua University, Beijing, 100084, People's Republic of China
| | - Xudong Liang
- Department of Mechanical and Aerospace Engineering, University of California, San Diego, La Jolla, CA, 92093, USA
| | - Ming Guo
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Yanping Cao
- Department of Engineering Mechanics, Institute of Biomechanics and Medical Engineering, Tsinghua University, Beijing, 100084, People's Republic of China
| | - Shengqiang Cai
- Department of Mechanical and Aerospace Engineering, University of California, San Diego, La Jolla, CA, 92093, USA.
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Peloquin JM, Elliott DM. A comparison of stress in cracked fibrous tissue specimens with varied crack location, loading, and orientation using finite element analysis. J Mech Behav Biomed Mater 2015; 57:260-8. [PMID: 26741533 DOI: 10.1016/j.jmbbm.2015.12.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2015] [Revised: 11/26/2015] [Accepted: 12/03/2015] [Indexed: 12/01/2022]
Abstract
Cracks in fibrous soft tissue, such as intervertebral disc annulus fibrosus and knee meniscus, cause pain and compromise joint mechanics. A crack concentrates stress at its tip, making further failure and crack extension (fracture) more likely. Ex vivo mechanical testing is an important tool for studying the loading conditions required for crack extension, but prior work has shown that it is difficult to reproduce crack extension. Most prior work used edge crack specimens in uniaxial tension, with the crack 90° to the edge of the specimen. This configuration does not necessarily represent the loading conditions that cause in vivo crack extension. To find a potentially better choice for experiments aiming to reproduce crack extension, we used finite element analysis to compare, in factorial combination, (1) center crack vs. edge crack location, (2) biaxial vs. uniaxial loading, and (3) crack-fiber angles ranging from 0° to 90°. The simulated material was annulus fibrosus fibrocartilage with a single fiber family. We hypothesized that one of the simulated test cases would produce a stronger stress concentration than the commonly used uniaxially loaded 90° crack-fiber angle edge crack case. Stress concentrations were compared between cases in terms of fiber-parallel stress (representing risk of fiber rupture), fiber-perpendicular stress (representing risk of matrix rupture), and fiber shear stress (representing risk of fiber sliding). Fiber-perpendicular stress and fiber shear stress concentrations were greatest in edge crack specimens (of any crack-fiber angle) and center crack specimens with a 90° crack-fiber angle. However, unless the crack is parallel to the fiber direction, these stress components alone are insufficient to cause crack opening and extension. Fiber-parallel stress concentrations were greatest in center crack specimens with a 45° crack-fiber angle, either biaxially or uniaxially loaded. We therefore recommend that the 45° center crack case be tried in future experiments intended to study crack extension by fiber rupture.
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Affiliation(s)
| | - Dawn M Elliott
- University of Delaware, 150 Academy St, 161 Colburn Lab, Newark, DE 19716, USA.
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25
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Haslach HW, Leahy LN, Fathi P, Barrett JM, Heyes AE, Dumsha TA, McMahon EL. Crack Propagation and Its Shear Mechanisms in the Bovine Descending Aorta. Cardiovasc Eng Technol 2015; 6:501-18. [PMID: 26577482 DOI: 10.1007/s13239-015-0245-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Accepted: 09/09/2015] [Indexed: 10/23/2022]
Abstract
Aortic dissection and rupture may involve circumferential shear stress in the circumferential-longitudinal plane. Inflation of bovine descending aortic ring specimens provides evidence of such shear from the non-uniform circumferential distortion of radial lines drawn on the circumferential-radial ring face. Delamination without tensile peeling induces cracks that propagate nearly circumferentially in the circumferential-longitudinal plane from the root of a radial cut representing rupture initiation in a ring. Translational shear deformation tests of small rectangular aortic wall blocks in the circumferential and longitudinal direction measure the consequences of such shear on substructures in the aortic wall, in particular the collagen fibers. The two directions of shear deformation produce no statistical difference in the shear stress response of the wall. Possibly, the interfiber connections between collagen fibers are put into tension by either translational shear deformation so that the stress measured reflects the tensile response of these connections. Wall rupture may involve failure of these connections; such failure is supported by the voids parallel to the collagen fibers observed in a histological study after translational shear. Further, interstitial fluid is redistributed by shear as evidenced by the measured weight loss of a set of specimens during the translational shear of blocks. Because the mass changes, mathematical modeling of aortic tissue in vitro as incompressible is an approximation. These observations suggest that no simple modification of classical rupture theories, whether based on energy functions, stress or strain, suffices to predict the rupture of hydrated soft biological tissue that has complex substructures.
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Affiliation(s)
- Henry W Haslach
- Department of Mechanical Engineering, University of Maryland, College Park, MD, 20742, USA.
| | - Lauren N Leahy
- Department of Mechanical Engineering, University of Maryland, College Park, MD, 20742, USA
| | - Parinaz Fathi
- Department of Mechanical Engineering, University of Maryland, College Park, MD, 20742, USA
| | - Joshua M Barrett
- Department of Mechanical Engineering, University of Maryland, College Park, MD, 20742, USA
| | - Amanda E Heyes
- Department of Mechanical Engineering, University of Maryland, College Park, MD, 20742, USA
| | - Thomas A Dumsha
- Department of Mechanical Engineering, University of Maryland, College Park, MD, 20742, USA
| | - Eileen L McMahon
- Department of Mechanical Engineering, University of Maryland, College Park, MD, 20742, USA
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26
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Giambini H, Qin X, Dragomir-Daescu D, An KN, Nassr A. Specimen-specific vertebral fracture modeling: a feasibility study using the extended finite element method. Med Biol Eng Comput 2016; 54:583-93. [PMID: 26239163 DOI: 10.1007/s11517-015-1348-x] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Accepted: 07/07/2015] [Indexed: 12/31/2022]
Abstract
Osteoporotic vertebral body fractures are an increasing clinical problem among the aging population. Specimen-specific finite element models, derived from quantitative computed tomography (QCT), have the potential to more accurately predict failure loads in the vertebra. Additionally, the use of extended finite element modeling (X-FEM) allows for a detailed analysis of crack initiation and propagation in various materials. Our aim was to study the feasibility of QCT/X-FEM analysis to predict fracture properties of vertebral bodies. Three cadaveric specimens were obtained, and the L3 vertebrae were excised. The vertebrae were CT scanned to develop computational models and mechanically tested in compression to measure failure load, stiffness and to observe crack location. One vertebra was used for calibration of the material properties from experimental results and CT gray-scale values. The two additional specimens were used to assess the model prediction. The resulting QCT/X-FEM model of the specimen used for calibration had 2 and 4% errors in stiffness and failure load, respectively, compared with the experiment. The predicted failure loads of the additional two vertebrae were larger by about 41-44% when compared to the measured values, while the stiffness differed by 129 and 40%. The predicted fracture patterns matched fairly well with the visually observed experimental cracks. Our feasibility study indicated that the QCT/X-FEM method used to predict vertebral compression fractures is a promising tool to consider in future applications for improving vertebral fracture risk prediction in the elderly.
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Abstract
This article reviews the diagnosis and treatment of cracked teeth, and explores common clinical examples of cracked teeth, such as cusp fractures, fractures into tooth furcations, and root fractures. This article provides alternative definitions of terms such as cracked teeth, complete and incomplete fractures and crack lines, and explores the scientific rationale for dental terminology commonly used to describe cracked teeth, such as cracked tooth syndrome, structural versus nonstructural cracks, and vertical, horizontal, and oblique fractures. The article explains the advantages of high magnification loupes (×6-8 or greater), or the surgical operating microscope, combined with co-axial or head-mounted illumination, when observing teeth for microscopic crack lines or enamel craze lines. The article explores what biomechanical factors help to facilitate the development of cracks in teeth, and under what circumstances a full coverage crown may be indicated for preventing further propagation of a fracture plane. Articles on cracked tooth phenomena were located via a PubMed search using a variety of keywords, and via selective hand-searching of citations contained within located articles.
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28
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Grill S, Dorgan KM. Burrowing by small polychaetes - mechanics, behavior and muscle structure of Capitella sp. ACTA ACUST UNITED AC 2015; 218:1527-37. [PMID: 25827841 DOI: 10.1242/jeb.113183] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Accepted: 03/10/2015] [Indexed: 11/20/2022]
Abstract
Worms of different sizes extend burrows through muddy sediments by fracture, applying dorso-ventral forces that are amplified at the crack tip. Smaller worms displace sediments less than larger worms and therefore are limited in how much force they can apply to burrow walls. We hypothesized that small worms would exhibit a transition in burrowing mechanics, specifically a lower limit in body size for the ability to burrow by fracture, corresponding with an ontogenetic transition in muscle morphology. Kinematics of burrowing in a mud analog, external morphology and muscle arrangement were examined in juveniles and adults of the small polychaete Capitella sp. We found that it moves by peristalsis, and no obvious differences were observed among worms of different sizes; even very small juveniles were able to burrow through a clear mud analog by fracture. Interestingly, we found that in addition to longitudinal and circular muscles needed for peristaltic movements, left- and right-handed helical muscles wrap around the thorax of worms of all sizes. We suggest that in small worms helical muscles may function to supplement forces generated by longitudinal muscles and to maintain hydrostatic pressure, enabling higher forces to be exerted on the crack wall. Further research is needed, however, to determine whether surficial sediments inhabited by small worms fail by fracture or plastically deform under forces of the magnitudes applied by Capitella sp.
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Affiliation(s)
- Susann Grill
- Dauphin Island Sea Lab, 101 Bienville Blvd., Dauphin Island, AL 36528, USA
| | - Kelly M Dorgan
- Dauphin Island Sea Lab, 101 Bienville Blvd., Dauphin Island, AL 36528, USA
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29
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Wang W, Elbanna A. Crack propagation in bone on the scale of mineralized collagen fibrils: role of polymers with sacrificial bonds and hidden length. Bone 2014; 68:20-31. [PMID: 25108082 DOI: 10.1016/j.bone.2014.07.035] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/20/2014] [Revised: 07/24/2014] [Accepted: 07/29/2014] [Indexed: 11/23/2022]
Abstract
Sacrificial bonds and hidden length (SBHL) in structural molecules provide a mechanism for energy dissipation at the nanoscale. It is hypothesized that their presence leads to greater fracture toughness than what is observed in materials without such features. Here, we investigate this hypothesis using a simplified model of a mineralized collagen fibril sliding on a polymeric interface with SBHL systems. A 1D coarse-grained nonlinear spring-mass system is used to model the fibril. Rate-and-displacement constitutive equations are used to describe the mechanical properties of the polymeric system. The model quantifies how the interface toughness increases as a function of polymer density and number of sacrificial bonds. Other characteristics of the SBHL system, such as the length of hidden loops and the strength of the bonds, are found to influence the results. The model also gives insight into the variations in the mechanical behavior in response to physiological changes, such as the degree of mineralization of the collagen fibril and polymer density in the interfibrillar matrix. The model results provide constraints relevant for bio-mimetic material design and multiscale modeling of fracture in human bone.
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Affiliation(s)
- Wenyi Wang
- Department of Civil and Environmental Engineering, University of Illinois Urbana Champaign, 205N. Mathews Ave, Urbana, IL 61801, USA.
| | - Ahmed Elbanna
- Department of Civil and Environmental Engineering, University of Illinois Urbana Champaign, 205N. Mathews Ave, Urbana, IL 61801, USA.
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30
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Von Forell GA, Hyoung PS, Bowden AE. Failure modes and fracture toughness in partially torn ligaments and tendons. J Mech Behav Biomed Mater 2014; 35:77-84. [PMID: 24747098 DOI: 10.1016/j.jmbbm.2014.03.020] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2013] [Revised: 03/19/2014] [Accepted: 03/31/2014] [Indexed: 10/25/2022]
Abstract
Ligaments and tendons are commonly torn during injury, yet the likelihood that untreated initial tears could lead to further tearing or even full rupture has proven challenging to predict. In this work, porcine Achilles tendon and human anterior longitudinal ligament samples were tested using both standard fracture toughness methods and complex loading conditions. Failure modes for each of 14 distinct testing cases were evaluated using a total of 131 soft tissue tests. Results showed that these soft tissues were able to completely resist any further crack propagation of an initial tear, regardless of fiber orientation or applied loading condition. Consequently, the major concern for patients with tendon or ligament tears is likely not reduction in ultimate tissue strength due to stress risers at the tip of the tear, but rather a question of whether or not the remaining cross-section is large enough to support the anticipated loading.
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Affiliation(s)
- Gregory A Von Forell
- Brigham Young University, Department of Mechanical Engineering, Provo, UT 84602, USA
| | - Peter S Hyoung
- Brigham Young University, Department of Mechanical Engineering, Provo, UT 84602, USA
| | - Anton E Bowden
- Brigham Young University, Department of Mechanical Engineering, Provo, UT 84602, USA.
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31
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Yahyazadehfar M, Nazari A, Kruzic JJ, Quinn GD, Arola D. An inset CT specimen for evaluating fracture in small samples of material. J Mech Behav Biomed Mater 2014; 30:358-68. [PMID: 24268892 PMCID: PMC4059206 DOI: 10.1016/j.jmbbm.2013.10.017] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2013] [Revised: 10/15/2013] [Accepted: 10/19/2013] [Indexed: 11/26/2022]
Abstract
In evaluations on the fracture behavior of hard tissues and many biomaterials, the volume of material available to study is not always sufficient to apply a standard method of practice. In the present study an inset Compact Tension (inset CT) specimen is described, which uses a small cube of material (approximately 2×2×2mm(3)) that is molded within a secondary material to form the compact tension geometry. A generalized equation describing the Mode I stress intensity was developed for the specimen using the solutions from a finite element model that was defined over permissible crack lengths, variations in specimen geometry, and a range in elastic properties of the inset and mold materials. A validation of the generalized equation was performed using estimates for the fracture toughness of a commercial dental composite via the "inset CT" specimen and the standard geometry defined by ASTM E399 (2006). Results showed that the average fracture toughness obtained from the new specimen (1.23±0.02MPam(0.5)) was within 2% of that from the standard. Applications of the inset CT specimen are presented for experimental evaluations on the crack growth resistance of dental enamel and root dentin, including their fracture resistance curves. Potential errors in adopting this specimen are then discussed, including the effects of debonding between the inset and molding material on the estimated stress intensity distribution. Results of the investigation show that the inset CT specimen offers a viable approach for studying the fracture behavior of small volumes of structural materials.
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Affiliation(s)
- M Yahyazadehfar
- University of Maryland Baltimore County, Department of Mechanical Engineering, 1000 Hilltop Circle, Baltimore, MD 21250, USA
| | - A Nazari
- University of Maryland Baltimore County, Department of Mechanical Engineering, 1000 Hilltop Circle, Baltimore, MD 21250, USA
| | - J J Kruzic
- Materials Science, School of Mechanical(,) Industrial, and Manufacturing Engineering, Oregon State University, Corvallis, OR, 97331, USA
| | - G D Quinn
- University of Maryland Baltimore County, Department of Mechanical Engineering, 1000 Hilltop Circle, Baltimore, MD 21250, USA
| | - D Arola
- University of Maryland Baltimore County, Department of Mechanical Engineering, 1000 Hilltop Circle, Baltimore, MD 21250, USA; Department of Endodontics, Prosthodontics, and Operative Dentistry, Baltimore College of Dental Surgery, University of Maryland, Baltimore, MD 21201, USA.
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Abstract
Due to changes in the bone quality during ageing the fracture risk increases. The influence of the different parameters affecting bone quality is not well understood. The Finite Element method offers the opportunity to determine the individual contribution of a parameter by changing single parameters. In this study, the ABAQUS extended Finite Elements Method (xFEM) was applied to simulate the crack propagation in compact bone samples using the quadratic nominal stress as crack criterion. Micro computed tomography images of compact-tension samples machined from a 19 and an 81 years old donor were used to generate Finite Element meshes consisting of linear tetrahedrons via Mimics. Cavities were modelled only in the estimated crack area to avoid a high number of degrees of freedom. Crack area was meshed with a higher number of smaller elements. The other areas were meshed with a small number of larger elements. The changes in the material constants due to the simplification of the model were taken into account by using effective material parameters in these partitions. Our results show that age-related loss in bone toughness results from increased porosity and loss in heterogeneity of material level properties.
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Affiliation(s)
- Silke Besdo
- Institute for Continuum Mechanics, Leibniz Universität Hannover, Hannover, Germany
- Department of Biomedical Engineering, Center of Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY, USA
| | - Deepak Vashishth
- Department of Biomedical Engineering, Center of Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY, USA
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Beaurepaire P, Valdebenito M, Schuëller G, Jensen H. Reliability-based optimization of maintenance scheduling of mechanical components under fatigue. Comput Methods Appl Mech Eng 2012; 221-222:24-40. [PMID: 23564979 PMCID: PMC3608029 DOI: 10.1016/j.cma.2012.01.015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/27/2011] [Revised: 01/13/2012] [Accepted: 01/29/2012] [Indexed: 06/02/2023]
Abstract
This study presents the optimization of the maintenance scheduling of mechanical components under fatigue loading. The cracks of damaged structures may be detected during non-destructive inspection and subsequently repaired. Fatigue crack initiation and growth show inherent variability, and as well the outcome of inspection activities. The problem is addressed under the framework of reliability based optimization. The initiation and propagation of fatigue cracks are efficiently modeled using cohesive zone elements. The applicability of the method is demonstrated by a numerical example, which involves a plate with two holes subject to alternating stress.
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Affiliation(s)
- P. Beaurepaire
- Institute of Engineering Mechanics, University of Innsbruck, Technikerstrasse 13, A-6020 Innsbruck, Austria
| | - M.A. Valdebenito
- Universidad Tecnica Federico Santa Maria, Dept. de Obras Civiles, Av. España 1680, Valparaiso, Chile
| | - G.I. Schuëller
- Institute of Engineering Mechanics, University of Innsbruck, Technikerstrasse 13, A-6020 Innsbruck, Austria
| | - H.A. Jensen
- Universidad Tecnica Federico Santa Maria, Dept. de Obras Civiles, Av. España 1680, Valparaiso, Chile
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