Non-linear FE2 multiscale simulation of damage, micro and macroscopic strains in polyamide 66-woven composite structures: analysis and experimental validation

Abstract This paper presents an experimental approach aimed at analyzing and validating a two-scale nonlinear Finite Element (FE2) simulation of a 3D composite structure. The studied composite material consists of polyamide thermoplastic matrix, exhibiting viscoelastic-viscoplastic behavior with ductile damage, reinforced by woven glass fabric whereby inelastic and anisotropic damage behavior is considered. The multiscale parallel computation is founded on the periodic homogenization at the microscopic scale, which considers the geometric description of the reinforcement’s architecture and accounts for time-dependent and non-linear local behavior of each constitutive phase. For the numerical implementation at microscopic and macroscopic scales, an advanced UMAT subroutine is developed and combined with a parallelization technique in the commercial software Abaqus/Standard. The multilevel computation is achieved simultaneously at both scales (microscopic and macroscopic) through an incremental scheme. Numerical results of the FE multiscale simulation are analyzed and compared with the experimental results obtained for different stacking sequence configurations of a 3D woven composite holed plate subjected to tension. Besides the good agreement between the experimental and the predicted load-displacement global responses, the numerical simulation of the macroscopic strain fields reasonably agrees with those measured experimentally through the Digital Image Correlation (DIC) technique. Furthermore, the performance and the capabilities of the multiscale (FE2) strategy are demonstrated getting access, at the microstructure scale, to the microscopic strain fields and the spatiotemporal distributions of the internal variables as well as the damage evolution in the polymer matrix and the reinforcement (yarns).