Fully integrated multi-scale modelling of damage and time-dependency in thermoplastic-based woven composites

Abstract

In this work, a multi-scale model established from the concept of periodic homogenization is utilized to predict the cyclic and time-dependent response of thermoplastic-based woven composites. The macroscopic behaviour of the composite is determined from finite element simulations of the representative unit cell of the periodic microstructure, where the local non-linear constitutive laws of the components are directly integrated, namely, the matrix and the yarns. The thermoplastic matrix is described by a phenomenological multi-mechanisms constitutive model accounting for viscoelasticity, viscoplasticity and ductile damage. For the yarns, a hybrid micromechanical–phenomenological constitutive model accounting for anisotropic damage and anelasticity induced by the presence of a diffuse micro-crack network is utilized. The capabilities of the overall multi-scale model are validated by comparing the numerical predictions with experimental data. Further illustrative examples are also provided, where the composite undergoes time-dependent deformations under uni-axial and non-proportional multi-axial loading paths. The multi-scale model is also employed to analyze the influence of the local deformation processes on the macroscopic response of the composite.

Extended mean-field homogenization of viscoelastic-viscoplastic polymer composites undergoing hybrid progressive degradation induced by interface debonding and matrix ductile damage

“…referred as the microcrack density) by assuming the scale separation between the voids and the homogenized interphase medium. One can recall that for a two-phase porous composite, the overall stiffness is given by (Praud et al, 2017b;Praud et al, 2020):…”

“…In this section, the modified Mori-Tanaka TFA framework developed in this work is employed to describe the load/unload nonlinear stress-strain response of unidirectional composites with evolving damage. The material system investigated herein is a glass/polyamide (PA66) composite, whose constituent phase material properties which are taken from Praud et al (2020) are listed in Table 2. The large property mismatch between the glass fiber and thermoplastic matrix phase yields large deformation and stress gradients in the vicinity of the fibers (interphase), hence providing a demanding test of the correctness and robustness of damage framework.…”

“…Figure 8 shows the three-phase finite-element unit cell model used for comparison with the modified Mori-Tanaka TFA approach, which is discretized into 11951 C3D10 elements. Periodic boundary conditions were applied on opposite faces of the unit cell, the details of which can be found in the paper by Praud et al (2020). To avoid duplication, the Weibull parameters are fixed as: , , and the interfacial void saturation limit is set as:…”

“…In the the voids are taken into account by assigning zero stiffness to the void inclusion phase. Using the classical Mori-Tanaka approach, the concentration tensor is calculated following formula(Praud et al, 2017b;Praud et al, 2020):…”

Detection and evaluation of barely visible impact damage in woven glass fabric reinforced polyamide 6.6/6 composite using ultrasonic imaging, X-ray tomography and optical profilometry

“…Typical stress-strain curves showing the response of the woven glass reinforced PA6.6/6 at 0° (or 90°) and that at 45° directions are given in Figure 2. The components of stiffness matrix are determined experimentally using ultrasonic bulk waves (Pomarède, 2018) and are compared with those obtained numerically using periodic homogenization (Praud, 2018) as represented in Table 2.…”