Mechanical characterization of the static and fatigue compressive properties of a new glass/flax/epoxy composite material using digital image correlation, thermographic stress analysis, and conventional mechanical testing

Material Properties and Engineering Performance of Bone Fracture Plates Made from Plant Fiber Reinforced Composites: A Review

Bone fracture plates are usually made from titanium alloy or stainless steel, which are much stiffer than bone. However, overly stiff plates can restrict axial interfragmentary motion at the fracture leading to delayed callus formation and healing, as well as causing bone "stress shielding" under the plate leading to bone atrophy, bone resorption, and plate loosening. Consequently, there have been many prior efforts to develop nonmetallic bone fracture plates with customized material properties using synthetic fibers (e.g., aramid, carbon, glass) in polymer resin. Even so, plant fibers (e.g., flax, roselle, sisal) offer additional advantages over synthetic fibers, such as availability, biodegradability, less toxicity during processing, lower financial cost, and recyclability. As such, there is an emerging interest in using plant fibers alone, or combined with synthetic fibers, to reinforce polymers for various applications. Thus, this is the first review article on the material properties and engineering performance of innovative bone fracture plates made from composite materials reinforced by plant fibers alone or supplemented using synthetic fibers. This article presents material-level fiber properties (e.g., elastic modulus, ultimate strength), material-level plate properties (e.g., fatigue strength, impact toughness), and bone-plate engineering performance (e.g., overall stiffness, plate stress), as well as discussing general findings, study quality, and future work. This article may help engineers and surgeons to design, fabricate, analyze, and utilize novel bone fracture plates.

Elastic Property Evaluation of Fiberglass and Epoxy Resin Composite Material Using Digital Image Correlation

This study focused on evaluating the sensitivity and limitations of the simplified equipment used in the Digital Image Correlation (DIC) technique, comparing them with the analog extensometer, based on the mechanical property data of a composite made of fiberglass and epoxy resin. The objectives included establishing a methodology based on the literature, fabricating samples through manual lamination, conducting mechanical tests according to the ASTM D3039 and D3518 standards, comparing DIC with the analog extensometer of the testing machine, and contrasting the experimental results with classical laminate theory. Three composite plates with specific stacking sequences ([0]3, [90]4, and [±45]3) were fabricated, and samples were extracted for testing to determine tensile strength, modulus of elasticity, and other properties. DIC was used to capture deformation fields during testing. Comparisons between data obtained from the analog extensometer and DIC revealed differences of 11.1% for the longitudinal modulus of elasticity E1 and 5.6% for E2. Under low deformation conditions, DIC showed lower efficiency due to equipment limitations. Finally, a theoretical analysis based on classical laminate theory, conducted using a Python script, estimated the longitudinal modulus of elasticity Ex and the shear strength of the [±45]3 laminate, highlighting a relative difference of 31.2% between the theoretical value of 7136 MPa and the experimental value of 5208 MPa for Ex.

Cytotoxicity of novel hybrid composite materials for making bone fracture plates

Bone fracture plates are usually made from steel or titanium, which are much stiffer than cortical bone. This may cause bone 'stress shielding' (i.e. bone resorption leading to plate loosening) and delayed fracture healing (i.e. fracture motion is less than needed to stimulate callus formation at the fracture). Thus, the authors previously designed, fabricated, and mechanically tested novel 'hybrid' composites made from inorganic and organic materials as potential bone fracture plates that are more flexible to reduce these negative effects. This is the first study to measure the cytotoxicity of these composites via the survival of rat cells. Cubes of carbon fiber/flax fiber/epoxy and glass fiber/flax fiber/epoxy had better cell survival vs. Kevlar fiber/flax fiber/epoxy (57% and 58% vs. 50%). Layers and powders made of carbon fiber/epoxy and glass fiber/epoxy had higher cell survival than Kevlar fiber/epoxy (96%-100% and 100% vs. 39%-90%). The presence of flax fibers usually decreased cell survival. Thus, carbon and glass fiber composites (with or without flax fibers), but not Kevlar fiber composites (with or without flax fibers), may potentially be used for bone fracture plates.

Finite Element Analysis: Connector Designs and Pontic Stress Distribution of Fixed Partial Denture Implant-Supported Metal Framework

This virtual study was designed to evaluate the stress-deformation of a metal fixed partial dentures (FPDs) pontic under different loads using two different connectors. The STL file was generated for a RPD of two implant-supported restorations. The Co-Cr metal substructure was designed with two types of connector design. The pontic is connected to implant-supported crowns with square and round shape connectors. This study was designed for a cementless-retained implant-supported FPD. Finite element modeling (FEM) is used to assess the stress and deformation of the pontic within a metal substructure as the FEM might provide virtual values that could have laboratory and clinical relevance. The Co-Cr alloy mechanical properties like the Poisson ratio and modulus of elasticity were based on the parameters of the three-dimensional structure additive method. Nonparametric analyses (Mann-Whitney U test) was used. The use of square or round connectors often resulted in non-significant changes in stress, and deformation under either three or each loaded point on the occlusal surface of a pontic (P > 0.05). However, the deformation revealed distinct variations between loads of the three points compared to each loaded point (P ≤ 0.05). According to this study data, the pontic occlusal surface appears to be the same in stress and deformation under different loads depending on whether square or round connectors are used. While at the same connector designs, the pontic occlusal surface deformed significantly at three loaded points than it did at each point.

Biomechanical stress analysis using thermography: A review

Biomechanics investigators are interested in experimentally measuring stresses experienced by dental structures, whole bones, joint replacements, soft tissues, normal limbs, etc. To do so, various experimental methods have been used that are based on acoustic, optical, piezo-resistive, or other principles, like digital image correlation, fiber optic sensors, photo-elasticity, strain gages, ultrasound, etc. Several biomechanical review papers have surveyed these research technologies, but they do not mention thermography. Thermography can identify temperature anomalies indicating low- or high-stress areas on a bone, implant, prosthesis, etc., which may need to be repaired, replaced, or redesigned to avoid damage, degradation, or failure. In addition, thermography can accurately predict a structure's cyclic fatigue strength. Consequently, this article gives an up-to-date survey of the scientific literature on thermography for biomechanical stress analysis. This review (i) describes the basic physics of thermography, thermo-elastic properties of biomaterials, experimental protocols for thermography, advantages, and disadvantages, (ii) surveys published studies on various applications that used thermography for biomechanical stress measurements, and (iii) discusses general findings and future work. This article is intended to inform biomechanics investigators about the potential of thermography for stress analysis.

A Review on Synthetic Fibers for Polymer Matrix Composites: Performance, Failure Modes and Applications

In the last decade, synthetic fiber, as a reinforcing specialist, has been mainly used in polymer matrix composites (PMC's) to provide lightweight materials with improved stiffness, modulus, and strength. The significant feature of PMC's is their reinforcement. The main role of the reinforcement is to withstand the load applied to the composite. However, in order to fulfill its purpose, the reinforcements must meet some basic criteria such as: being compatible with the matrix, making chemical or adhesion bonds with the matrix, having properties superior to the matrix, presenting the optimal orientation in composite and, also, having a suitable shape. The current review reveals a detailed study of the current progress of synthetic fibers in a variety of reinforced composites. The main properties, failure modes, and applications of composites based on synthetic fibers are detailed both according to the mentioned criteria and according to their types (organic or inorganic fibers). In addition, the choice of classifications, applications, and properties of synthetic fibers is largely based on their physical and mechanical characteristics, as well as on the synthesis process. Finally, some future research directions and challenges are highlighted.

Mechanical test study in composites using digital holographic interferometry and optical coherence tomography simultaneously

A dual optical configuration to inspect the internal and external mechanical response of a composite specimen is presented. The inspection simultaneously uses two equally aligned optical techniques, digital holographic interferometry and Fourier domain optical coherence tomography, to retrieve surface and internal data, respectively. The sample under study is a composite specimen of poly-methyl-methacrylate reinforced with metallic particles. Two different sets of samples are analyzed to compare their mechanical behavior. A homemade, fully controlled testing machine is used to apply a controlled compression load while each technique registers an image. In this form, the surface and internal optical phase measurements are correlated to the same compression value for comparison purposes. Results for each technique are directly presented as simultaneous displacement maps, and a discussion and conclusion of this proposed dual method of inspection are presented.