In-situ effect in cross-ply laminates under various loading conditions analyzed with hybrid macro/micro-scale computational models

In this work, mull-scale finite element analyses based on three-dimensional (3D) hybrid macro/micro-scale computational models subjected to various loading conditions are carried out to examine the in-situ effect imposed by the neighboring plies on the failure initiation and propagation of cross-ply laminates. A detailed comparative study on crack suppression mechanisms due to the effect of embedded laminar thickness and adjacent ply orientation is presented. Furthermore, we compare the results of in-situ transverse failure strain and strength between the computational models and analytical predictions. Good agreements are generally observed, indicating the constructed computational models are highly accurate to quantify the in-situ effect. Subsequently, empirical formulas for calculating the in-situ strengths as a function of embedded ply thickness and different ply angle between embedded and adjacent plies are developed, during which several material parameters are obtained using a reverse fitting method. Finally, a new set of failure criteria for sigma(22)-tau(12), sigma(22)-tau(23), and sigma(11)-tau(12) accounting for the in-situ strengths are proposed to predict laminated composites failure under multi-axial stress states. This study demonstrates an effective and efficient computational technique towards the accurate prediction of the failure behaviors and strengths of cross-ply laminates by including the in-situ effects.

Automated summary

This study conducted mull-scale finite element analyses based on 3D hybrid macro/micro-scale computational models to investigate the in-situ effect imposed by neighboring plies on the failure initiation and propagation of cross-ply laminates. The results showed good agreements between the computational models and analytical predictions, indicating high accuracy in quantifying the in-situ effect. Empirical formulas for in-situ strengths as a function of embedded ply thickness and different ply angle were developed, and new failure criteria accounting for the in-situ strengths were proposed to predict laminated composites failure under multi-axial stress states.