https://sam.ensam.eu:443 The DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material. Sun, 15 Mar 2026 06:00:50 GMT 2026-03-15T06:00:50Z http://hdl.handle.net/10985/24062 Experimental and multi-scale investigation of the mechanical behavior of mechanically recycled glass fiber reinforced thermoplastic composites SEKKAL, Saïf Eddine; MERAGHNI, Fodil; CHATZIGEORGIOU, George; PELTIER, Laurent; DURAND, Nelly Fiber reinforced thermoplastic polymer composites have gained a lot of attention over the past two decades, due to their excellent mechanical performance and their lightweight resulting in lower CO 2 emissions for airplanes and vehicles. However, with increased demand for these materials, research regarding environmentally friendly recycling routes has become a central environmental issue. Mechanical recycling by exploiting the melting properties of thermoplastic polymers has proven an excellent way of increasing the value of recycled composites, especially compared to other mainstream techniques. This research aims at investigating the relationship between the microstructure of these materials and their resulting mechanical properties. The studied material is processed by compressing molding chopped woven composites chips, made from a polyamide 6 matrix reinforced with glass fibers. A novel microstructural investigation for these types of materials was conducted using multiple destructive and non-destructive techniques, along with tensile and flexural tests on specimens made from different chips sizes. This investigation revealed a hierarchical fiber structure with a mixture of intact woven chips and randomly oriented unidirectional fiber strands. This microstructure causes complex damage propagation mechanisms and variability in mechanical performance. This hinders development and large-scale commercialization of these materials and favors other less eco-friendly recycling strategies. Therefore, developing accurate predictive models for the mechanical response of these materials is important, thus enabling fast design optimization. A multi-scale predictive model is hence proposed based on extensive qualitative and quantitative microstructural investigation and is able to capture the anisotropy of the material. This approach is validated on experimental data from a recycled PA6/Glass fiber composite and can be applied for other recycled materials in the same manner. Fri, 01 Sep 2023 00:00:00 GMT http://hdl.handle.net/10985/24062 2023-09-01T00:00:00Z SEKKAL, Saïf Eddine MERAGHNI, Fodil CHATZIGEORGIOU, George PELTIER, Laurent DURAND, Nelly Fiber reinforced thermoplastic polymer composites have gained a lot of attention over the past two decades, due to their excellent mechanical performance and their lightweight resulting in lower CO 2 emissions for airplanes and vehicles. However, with increased demand for these materials, research regarding environmentally friendly recycling routes has become a central environmental issue. Mechanical recycling by exploiting the melting properties of thermoplastic polymers has proven an excellent way of increasing the value of recycled composites, especially compared to other mainstream techniques. This research aims at investigating the relationship between the microstructure of these materials and their resulting mechanical properties. The studied material is processed by compressing molding chopped woven composites chips, made from a polyamide 6 matrix reinforced with glass fibers. A novel microstructural investigation for these types of materials was conducted using multiple destructive and non-destructive techniques, along with tensile and flexural tests on specimens made from different chips sizes. This investigation revealed a hierarchical fiber structure with a mixture of intact woven chips and randomly oriented unidirectional fiber strands. This microstructure causes complex damage propagation mechanisms and variability in mechanical performance. This hinders development and large-scale commercialization of these materials and favors other less eco-friendly recycling strategies. Therefore, developing accurate predictive models for the mechanical response of these materials is important, thus enabling fast design optimization. A multi-scale predictive model is hence proposed based on extensive qualitative and quantitative microstructural investigation and is able to capture the anisotropy of the material. This approach is validated on experimental data from a recycled PA6/Glass fiber composite and can be applied for other recycled materials in the same manner. http://hdl.handle.net/10985/26182 Multiscale modeling of mechanically recycled glass fiber reinforced polyamide 6 composites accounting for viscoelasticity, viscoplasticity, and anisotropic damage SEKKAL, Saïf Eddine; MERAGHNI, Fodil; CHATZIGEORGIOU, George; PRAUD, Francis; DURAND, N. Fiber-reinforced thermoplastic composites are valued for their strength-to-weight ratio, cost-effectiveness, and recyclability, highlighting the need for efficient recycling technologies amid environmental concerns. This study addresses these challenges by examining the mechanical response of recycled glass fiber reinforced polyamide 6 composites and modeling their nonlinear, time-dependent behavior under complex loading conditions. Advanced nonlinear constitutive and multiscale models, initially developed for conventional fiber composites, are adapted to capture the stochastic response of recycled materials. These models integrate viscoelasticity, viscoplasticity and damage in the polymer matrix and account for anisotropic damage in the strands, addressing the heterogeneity introduced by the recycling process. A modified random sequential adsorption technique replicates the microstructures for nonlinear response modeling. Hypotheses based on microstructural investigations consider processing effects that disrupt the initial chip woven structure and create matrix-rich areas. The model captures anisotropy and variability observed in experimental data, providing a reliable framework for predicting the performance of recycled thermoplastic com- posites and improving the understanding of the relationship between microstructure and mechanical properties, with a focus on inelastic nonlinear behavior. Sat, 01 Mar 2025 00:00:00 GMT http://hdl.handle.net/10985/26182 2025-03-01T00:00:00Z SEKKAL, Saïf Eddine MERAGHNI, Fodil CHATZIGEORGIOU, George PRAUD, Francis DURAND, N. Fiber-reinforced thermoplastic composites are valued for their strength-to-weight ratio, cost-effectiveness, and recyclability, highlighting the need for efficient recycling technologies amid environmental concerns. This study addresses these challenges by examining the mechanical response of recycled glass fiber reinforced polyamide 6 composites and modeling their nonlinear, time-dependent behavior under complex loading conditions. Advanced nonlinear constitutive and multiscale models, initially developed for conventional fiber composites, are adapted to capture the stochastic response of recycled materials. These models integrate viscoelasticity, viscoplasticity and damage in the polymer matrix and account for anisotropic damage in the strands, addressing the heterogeneity introduced by the recycling process. A modified random sequential adsorption technique replicates the microstructures for nonlinear response modeling. Hypotheses based on microstructural investigations consider processing effects that disrupt the initial chip woven structure and create matrix-rich areas. The model captures anisotropy and variability observed in experimental data, providing a reliable framework for predicting the performance of recycled thermoplastic com- posites and improving the understanding of the relationship between microstructure and mechanical properties, with a focus on inelastic nonlinear behavior.