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Elastodynamic Behaviour of Laminate Structures with Soft Thin Interlayers: Theory and Experiment. MATERIALS 2022; 15:ma15041307. [PMID: 35207846 PMCID: PMC8874576 DOI: 10.3390/ma15041307] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Revised: 01/27/2022] [Accepted: 01/30/2022] [Indexed: 11/17/2022]
Abstract
Laminate structures composed of stiff plates and thin soft interlayers are widely used in aerospace, automotive and civil engineering encouraging the development of reliable non-destructive strategies for their condition assessment. In the paper, elastodynamic behaviour of such laminate structures is investigated with emphasis on its application in ultrasonic based NDT and SHM for the identification of interlayer mechanical and interfacial contact properties. A particular attention is given to the practically important frequency range, in which the wavelength considerably exceeds the thickness of the film. Three layer model with spring-type boundary conditions employed for imperfect contact simulation is used for numerical investigation. Novel effective boundary conditions are derived via asymptotic expansion technique and used for analysis of the peculiar properties of elastic guided waves in considered laminates. It is revealed that the thin and soft film influences the behaviour of the laminate mainly via the effective stiffnesses being a combination of the elastic moduli of the film, its thickness and interface stiffnesses. To evaluate each of these parameters separately (or to figure out that the available experimental data are insufficient), a step-wise procedure employing the effective boundary conditions is proposed and tested versus the laser Doppler vibrometry data for Lamb waves in Aluminium/Polymer film/Alumunium structure. A good agreement between theoretical and experimental data is demonstrated for a certain symmetric laminate specimen. The possibility of using film-related thickness resonance frequencies to estimate the film properties and contact quality is also demonstrated. Additionally, the rich family of edge waves is also investigated, and the splitting of fundamental edge waves into pairs is revealed.
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Kamal I, Razak HRA, Abdul Karim MK, Mashohor S, Liew JYC, Low YJ, Zaaba NA, Norkhairunnisa M, Rafi NASM. Mechanical and Imaging Properties of a Clinical-Grade Kidney Phantom Based on Polydimethylsiloxane and Elastomer. Polymers (Basel) 2022; 14:polym14030535. [PMID: 35160523 PMCID: PMC8840541 DOI: 10.3390/polym14030535] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 12/08/2021] [Accepted: 12/10/2021] [Indexed: 02/01/2023] Open
Abstract
Medical imaging phantoms are considered critical in mimicking the properties of human tissue for calibration, training, surgical planning, and simulation purposes. Hence, the stability and accuracy of the imaging phantom play a significant role in diagnostic imaging. This study aimed to evaluate the influence of hydrogen silicone (HS) and water (H2O) on the compression strength, radiation attenuation properties, and computed tomography (CT) number of the blended Polydimethylsiloxane (PDMS) samples, and to verify the best material to simulate kidney tissue. Four samples with different compositions were studied, including samples S1, S2, S3, and S4, which consisted of PDMS 100%, HS/PDMS 20:80, H2O/PDMS 20:80, and HS/H2O/PDMS 20:40:40, respectively. The stability of the samples was assessed using compression testing, and the attenuation properties of sample S2 were evaluated. The effective atomic number of S2 showed a similar pattern to the human kidney tissue at 1.50 × 10−1 to 1 MeV. With the use of a 120 kVp X-ray beam, the CT number quantified for S2, as well measured 40 HU, and had the highest contrast-to-noise ratio (CNR) value. Therefore, the S2 sample formulation exhibited the potential to mimic the human kidney, as it has a similar dynamic and is higher in terms of stability as a medical phantom.
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Affiliation(s)
- Izdihar Kamal
- Department of Medical Imaging, School of Health Sciences, KPJ Healthcare University College, Nilai 71800, Negeri Sembilan, Malaysia; (I.K.); (N.A.Z.); (N.A.S.M.R.)
- Department of Physics, Faculty of Science, University of Putra Malaysia, Seri Kembangan 43400, Selangor, Malaysia; (J.Y.C.L.); (Y.J.L.)
| | - Hairil Rashmizal Abdul Razak
- Department of Radiology, Faculty of Medicine and Health Sciences, University of Putra Malaysia, Seri Kembangan 43400, Selangor, Malaysia;
| | - Muhammad Khalis Abdul Karim
- Department of Physics, Faculty of Science, University of Putra Malaysia, Seri Kembangan 43400, Selangor, Malaysia; (J.Y.C.L.); (Y.J.L.)
- Correspondence: ; Tel.: +60-192140612
| | - Syamsiah Mashohor
- Department of Computer and Communication Systems, Faculty of Engineering, University of Putra Malaysia, Seri Kembangan 43400, Selangor, Malaysia;
| | - Josephine Ying Chyi Liew
- Department of Physics, Faculty of Science, University of Putra Malaysia, Seri Kembangan 43400, Selangor, Malaysia; (J.Y.C.L.); (Y.J.L.)
| | - Yiin Jian Low
- Department of Physics, Faculty of Science, University of Putra Malaysia, Seri Kembangan 43400, Selangor, Malaysia; (J.Y.C.L.); (Y.J.L.)
| | - Nur Atiqah Zaaba
- Department of Medical Imaging, School of Health Sciences, KPJ Healthcare University College, Nilai 71800, Negeri Sembilan, Malaysia; (I.K.); (N.A.Z.); (N.A.S.M.R.)
- Diagnostic Imaging Services, KPJ Seremban Specialist Hospital, Lot 6219&6220, Jalan Toman 1 Kemayan Square, Seremban 70200, Negeri Sembilan, Malaysia
| | - Mazlan Norkhairunnisa
- Institute of Advanced Technology, University of Putra Malaysia, Seri Kembangan 43400, Selangor, Malaysia;
| | - Nur Athirah Syima Mohd Rafi
- Department of Medical Imaging, School of Health Sciences, KPJ Healthcare University College, Nilai 71800, Negeri Sembilan, Malaysia; (I.K.); (N.A.Z.); (N.A.S.M.R.)
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Ebrahimi H, Ali H, Ghosh R. Coulomb friction in twisting of biomimetic scale-covered substrate. BIOINSPIRATION & BIOMIMETICS 2020; 15:056013. [PMID: 32575081 DOI: 10.1088/1748-3190/ab9f80] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Biomimetic scale-covered substrates provide geometric tailorability via scale orientation, spacing and also interfacial properties of contact in various deformation modes. No work has investigated the effect of friction in twisting deformation of biomimetic scale-covered beams. In this work, we investigate the frictional effects in the biomimetic scale-covered structure by developing an analytical model verified by finite element simulations. In this model, we consider dry (Coulomb) friction between rigid scales surfaces, and the substrate as the linear elastic rectangular beam. The obtained results show that the friction has a dual contribution on the system by advancing the locking mechanism due to change of mechanism from purely kinematic to interfacial behavior, and stiffening the twist response due to sharp increase in the engagement forces. We also discovered, by increasing the coefficient of friction potentially using engineering scale surfaces to a critical coefficient, the system could reach to instantaneous post-engagement locking. The developed model outlines analytical relationships between geometry, deformation, frictional force and strain energy, to design biomimetic scale-covered metamaterials for a wide range of applications.
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Affiliation(s)
- Hossein Ebrahimi
- Department of Mechanical and Aerospace Engineering, University of Central Florida, Orlando, FL 32816, United States of America
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High Moisture Accelerated Mechanical Behavior Degradation of Phosphor/Silicone Composites Used in White Light-Emitting Diodes. Polymers (Basel) 2019; 11:polym11081277. [PMID: 31370367 PMCID: PMC6722709 DOI: 10.3390/polym11081277] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Revised: 07/11/2019] [Accepted: 07/21/2019] [Indexed: 02/06/2023] Open
Abstract
In a high-power white light emitting diode (LED) package, the phosphor/silicone composite is typically used for photometric and colorimetric conversions, ultimately producing the white light. However, the phosphor/silicone composite is always exposed under harsh environments with high temperature, high blue light irradiation and high moisture when the LED operates. Therefore, its reliability issue has become one of the critical bottlenecks to improve the lifetime of a high-power white LED package. As the curing process and mechanical behavior of phosphor/silicone composite essentially determine its reliability, this paper firstly uses an in situ viscosity monitoring approach combined with Differential Scanning Calorimetry (DSC) and Fourier Transform Infrared Spectroscopy (FTIR) analysis to explain the curing mechanism of a phosphor/silicone composite by taking the effects of temperature and phosphor mass fraction into consideration. Then, the mechanical properties of phosphor/silicone composites aged under a long-term high moisture condition are evaluated by using the tensile test. Meanwhile, the finite element (FE) simulations, the Mori–Tanaka theoretical estimations and the microstructure analysis are applied to investigate the high moisture induced degradation mechanisms. The results show that: (1) the in situ measured isothermal viscosity curves of both pristine silicone and phosphor/silicone composites follow the Arrhenius empirical model, and high temperature and high phosphor mass fraction can increase the curing rate; (2) the hydrosilylation reaction between silicones determines the curing mechanism of phosphor/silicone composite; (3) the tensile test, FE simulation and Mori–Tanaka theoretical prediction results confirm that the Young’s modulus of phosphor/silicone composite increases by gradually adding phosphors; and (4) the Young’s modulus of phosphor/silicone composite increases after the high moisture ageing test, which can be attributed to the oxidation and cross-linking reaction of silicone and the hydrolysis of phosphor powders.
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Park JY, Ko YB, La M, Yoon GS. A Study on Mechanical Characteristics of Phosphor Film Containing Methyl Silicone Resin Based on Crosslinking Reaction Analysis. Polymers (Basel) 2018; 10:E370. [PMID: 30966405 PMCID: PMC6415198 DOI: 10.3390/polym10040370] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Revised: 03/23/2018] [Accepted: 03/24/2018] [Indexed: 11/16/2022] Open
Abstract
This study reveals a methodological research for predicting mechanical properties of phosphor films through the chemical crosslinking reaction of methyl silicone resin during fabrication of the phosphor films. Crosslinking point according to the type of methyl silicone resins was verified through the magnitude of the absorption peak of the functional group and the curing reaction heat. Then, we measured mechanical properties of the fabricated phosphor films. As a result, it was figured out that the number of the crosslinking point was directly proportional to the total curing reaction heat, and also affected the mechanical properties of the phosphor films. Based on the correlation of curing reaction heat and crosslinking point of the methyl silicone resins and mechanical properties of the fabricated phosphor films, we proposed a methodology that can understand and control the phosphor films in advance of finishing the fabrication of the final phosphor products.
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Affiliation(s)
- Jeong Yeon Park
- Molds & Dies Technology R & D Group, Korea Institute of Industrial Technology (KITECH), Incheon 21999, Korea.
| | - Young Bae Ko
- Molds & Dies Technology R & D Group, Korea Institute of Industrial Technology (KITECH), Incheon 21999, Korea.
| | - Moonwoo La
- Molds & Dies Technology R & D Group, Korea Institute of Industrial Technology (KITECH), Incheon 21999, Korea.
| | - Gil Sang Yoon
- Molds & Dies Technology R & D Group, Korea Institute of Industrial Technology (KITECH), Incheon 21999, Korea.
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