Numerical estimation of the mode I strain energy release rate in woven-ply thermoplastic-based composites at high temperature based on Gθ method

Abstract

The present work was aimed at estimating the mode I strain energy release rate at crack initiation in woven-ply thermoplastic (TP) based laminates at high temperature T>Tg. A linear spectral viscoelastic model and a generalized Norton viscoplastic model were used to account for the time-dependent behavior of TP-based composite laminates, which are exacerbated at high temperature. To precisely evaluate the fracture parameters (e.g. R-curves) in TP composites, a study on the mesh type and its refinement was carried out. Using the finite element code Cast3m, the Gθ method was applied in order to test its capability to determine the mode I strain energy release rate for different testing conditions. (5)-Harness satin weave carbon fabric reinforced PolyPhenylene Sulfide (5HS C/PPS) laminates have been studied with two different stacking sequences: a Quasi-Isotropic (QI) sequence characterized by a fibre-dominated behaviour and an Angle-Ply (AP) sequence whose behaviour is matrix-dominated. Tensile tests have been simulated on Single-Edge-Notch (SEN) specimens (with different notch lengths) subjected to quasi-static loadings in order to investigate the effect of time-dependent behaviors on translaminar failure and strain energy release rate. The R-curves have been derived from the computation of the strain energy release rate and the corresponding crack length. Ultimately, it is possible to build R-curves based on the evaluation of fracture toughness for different ratios a/w and to compare these curves to the ones obtained from experiments.