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Background: Nowadays, natural fibers are used in all industrial fields, particularly in automotive technology and civil engineering. This great emergence is due to their biodegradability, recyclability and have no environmental effect. Objective: In this article, the effect of raffia, alfa and sisal fibers on the damage of biocomposite materials (raffia/PLA (polylactic acid), alfa/PLA and sisal/PLA), subjected to the same mechanical shear stress, has been investigated. Method: To calculate the damage to the interface, the genetic operator crossing is employed based on the fiber and matrix damage. Result: The results have shown that the raffia / PLA and alfa/PLA biocomposite materials are better mechanical properties compared to sisal / PLA, this observation has been confirmed by different values of interface damage of the biocomposite studied. Conclusion: The numerical results are similar and coincide perfectly with the results of Cox where he demonstrated that the Young's modulus of fibers improves the resistance of the interface. These conclusions are in very good agreement with our numerical data presented by the red cloud, and in good agreement with the work presented by Antoine Le Duigou et al. and Bodros et al. in which they have shown that natural fibers greatly improve the physical characteristics of composite materials.

Background: The objective of sustainable development in the field of materials necessitates and demands the substitution of the basic constituents of a composite material (carbon, glass, etc.) by natural reinforcements, which have a very important role in the protection of the environment and to subsequently have new materials with good properties compared to socalled traditional materials. Objective: In this context, we have investigated using genetic modeling based on probabilistic models the effect of thermal stress on transversal damage of a bio-composite hybrid Flax- Hemp/PE material. Methods: Our model genetic is based on probabilistic models of Weibull and the different values of the thermal stress were calculated by the Lebrun equation. To validate our theoretical calculations, we used the nonlinear parameter β in the Hoock law of the nonlinear acoustic technique to trace the curves of the damage under the mechanical and thermal stress. Results: The results obtained with a genetic simulation are in good agreement with the results found by Clément Gourier and Raphaël Kueny, who have shown that flax and hemp fibers (bark/Liberian fibers) are good reinforcements of the Polyethylene matrix; we found also found that our hybrid biocomposite material Flax-Hemp/PE is resistant in particular, a part of this material is of plant origin and gives us environmental benefit. Conclusion: It should be noted that the results obtained by the genetic simulation are in good agreement with the results obtained by the nonlinear acoustic technique mentioned by the green curve in all the figures. In perspective, it would be interesting to see, later, the effect of humidity on the damage of the matrix fiber interface of a hybrid biocomposite.

The natural plant fibers and biopolymers are a very important alternative to replace the inorganic fibers most used in the mechanical reinforcement of composite materials (carbon, glass, …) and synthetic polymers (Epoxy, PEEK, …), and at the same time they have a very low environmental impact and a very reasonable price. In this article, we have studied, by a numerical simulation based on genetic approach, the fiber-matrix interface damage of composite materials made up from the PHA (polyhydroxyalkanoates) matrix and the carbon, glass, jute, and hemp reinforcements with the same volume fraction equal to 30% for each fiber chosen. Our results showed that the damage at the fiber-matrix interface of the biocomposite hemp/PHA is the lowest compared with the other biocomposite materials glass/PHA, jute/PHA, and carbon/PHA. This finding is similar to that found by Antoine Le Duigou et al. and Bodros et al., where they have shown experimentally that the natural reinforcements greatly improve the properties of composite materials and also they have a very low environmental impact. To our knowledge, no published research reports on the study of fiber-matrix interface damage of biocomposite materials based on PHAs and carbon, glass, jute, and hemp fibers for potential textile applications, packaging, and other interesting areas.

Background:: The composite materials are more efficient and more resistant compared to so-called traditional materials. The application of continuous and variable forces modifies the properties of the materials, and generates the formation of cracks which lead to the rupture of structures. Objective:: The objective of this work is to study the reliability and the origin of the resistance of each fiber-matrix interface of the two hybrid composite materials studied. Methods:: In this study, the genetic algorithm is based on Weibull’s probabilistic approach to calculate the damage to the interface and also on the Cox model to find and initialize the different values used in simulation model. Results:: The results obtained by genetic modeling, have shown that the hybrid Carbon High Modulus (HM)/Basalt/Polyester composite is the most resistant to the mechanical stresses applied comparing with that of Carbon High Strength (HS)/Basalt/Polyester. These results were confirmed by the level of damage to the interface found for the two materials studied and that the interface shear damage of the hybrid Carbon HM/Basalt/Polyester composite is much lower by 13% compared to that of Carbon HS/Basalt/Polyester. Conclusion:: The calculations are in good agreement with the analytical results of Cox, where he demonstrated that Young’s modulus of the fibers has an important influence on the shear strength of the fiber/matrix interface of composite materials.

More recently, various techniques have been implemented for the sensors manufacturing purpose, such as fiber Bragg gratings fibers (FBG) that allows variable core refractive index suitable for a large scale of measurements types, fiber optic evanescent waves (FOEW) for water parameters measurement, microstructured and crystal photonic optical fibers, polymers optical fiber (POFs), and so on. In this perspective, the objective of this work is to study the reliability and the origin of the resistance of each fiber-matrix interface of the composite materials PMMA/PEEK, Topas/PEEK, and Topas-Zeonex/PEEK. The genetic simulation is based on the probabilistic approach of Weibull to calculate the damage at the interface by crossing the two damages of the matrix and the fiber respectively. The results show that the PMMA/PEEK composite is the most resistant to the mechanical stresses applied compared to those Topas/PEEK and Topas-Zeonex/PEEK; these results were confirmed by the level of damage to the interface observed for the studied materials. The performed calculations are in good agreement with the analytical results of Cox, where he demonstrated that Young's modulus of fibers have an important influence on the shear strength of the fiber-matrix interface of composite materials. Based on the obtained results, the present study gives the opportunity for the proposed materials (PMMA/PEEK and Zeonex/PEEK) to be as potential candidates for the smart digital applications and telecoms aims.

Background: In this paper, we have studied the improvement of the physical and chemical properties of the fiber-matrix interface of a Biocomposite based on the copolymer polylactic acid (PLA). Methodology: We have developed an analytical model using a genetic approach to locate the interface damage under the effect of mechanical stress, temperature and humidity. Our simulation is based on Weibull's probabilistic approach and the law of water diffusion in polymer matrix, the diffusion is generated by Fick's law. Results: Our results show that the interface of Biocomposite (Starch-PLA) is the most resistant to the different constraints applied and that the physical and chemical properties of this material are much more improved compared to other materials studied by the same genetic model. Conclusion: Our calculations coincide perfectly with the conclusions of Antoine et al. who determined that natural fibers improve the physical properties of composite materials.

In this paper, we have studied the effect of thermal stress on the damage of fiber-matrix interface of a hybrid biocomposite composed of two natural fibers, Hemp, Sisal, and Starch matrix. Our genetic modeling used the nonlinear acoustic technique based on Cox’s analytical model, Weibull’s probabilistic model, and Lebrun’s model describing the thermal stress by the two coefficients of expansion. The stress applied to our representative elementary volume is a uni-axial tensile stress. The numerical simulation shows that the Hemp- Sisal/Starch hybrid biocomposite is most resistant to thermal stresses as compared with Hemp/Starch biocomposite. It also shows that hybrid biocomposite materials have a high resistance to applied stresses (mechanical and thermal) compared to traditional materials and biocomposite materials. The results obtained in our study coincide perfectly with the results of Antoine et al., which showed through experimental tests that natural fibers perfectly improve the mechanical properties of biocomposite materials.

In this work, we have investigated the effect of the natural Kenaf reinforcement on the improvement of the interfacile bond between two types of epoxy and Polypropylene (PP) matrix. Our genetic model is based on Weibull's probabilistic models and on Cox's interface model. The moisture content for each material is determined by Fick's law. Our simulation results show that the most resistant interface is that of Kenaf-Polypropylene compared to the other interfaces. This result coincides perfectly with the experimental data found by Paul Wambua et al. Which have shown that Kenaf is a promoter fiber for the improvement of the mechanical properties of biocomposite used in the field of civil engineering.

In this study, the glass transition temperatures T g of both polymethacrylamide (PMAAM) and polymethylmethacrylate (PMMA) polymers, and their related copolymers P(MMA(1 − x) MAAM(x)) at various composition (x) were calculated, using molecular dynamics simulation. Calculations are performed using AMBER force field to describe the potential energies of homopolymers and copolymers structures. We have employed the static method to determine the bulk modulus, Young’s modulus, shear modulus and Poisson’s ratio at temperature 300 K. Our results stay in good agreement with the experimental ones. The T g of PMAAM (213.3 °C) is greater than T g of PMMA (115.9 °C) which is explained by the difference in their chemical structures, while the T g increases linearly with increasing composition (x) in copolymer P(MMA(1 − x)MAAM(x)). From our findings, we have investigated the viscoelastic behavior at different regions to predict the effect of temperature on the mechanical properties of these polymers and copolymers.

This work aims to describe the behavior of the interface using the method of load transfer between fiber and matrix in a composite material. Our contribution is to track the Evolution of the thermomechanical behavior by establishing a new mathematical model that describes the variation of shear stress along the interface. This model has been implemented in code in C++. The results revealed that the shear of the interface increases with temperature. This increase is partly due to the difference in expansion coefficient between fiber and matrix. The composite studied is T300/914; Carbon-Epoxy.

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International audience; The research described herein was aimed at gaining a better understanding of the behavior up to the fracture of laminate composite structures. An elastoplastic damage model was developed to describe the behavior of these structures in the greatest detail possible. The damage is modeled on each elementary constituent. Then a complete model at meso (intermediate) scale is obtained by applying a homogenization method.This model takes into account the transverse tensile and shear damage of matrix and fibre-matrix interface, as well as the nonlinear behavior of the fibre under axial compression. Plasticity develops only in the matrix and its flow is blocked in the direction of the fibres. It is modeled by an anisotropic yield criterion (of the HILL type) which takes not only the transverse and shear stress into account but which also includes isotropic and nonlinear kinematic hardening.The model developed was included in the nonlinear finite element "Castem 2000" to allow comparisons between numerical and experimental results. There is a good agreement between the simulated and experimental data. However, the model could advantageously be extended to take the phenomena such as viscoplasticity into account.