A multiscale hybrid approach for damage and final failure predictions of composite structures

Abstract

This paper presents a multiscale hybrid approach for predicting damage and failure of laminated composite structures based on the thermo-mechanical properties (stress/strain behaviour and strength) of the unidirectional plies. This kind of approach is thus predictive for different stacking sequences. The approach introduces viscosity of the matrix in order to obtain an accurate description of the mesoscopic behaviour, especially the non-linearity under shear loading. The failure criterion used is based on physical principles and introduces micromechanical aspects (such as the effect of the local debonding on the non-linear failure behaviour) at the mesoscopic scale. The main improvements, over those proposed in the second world-wide failure exercise, are related to (1) the evolution and effects of the mesoscopic cracks and (2) the coupling between those cracks and delamination (inter-ply damage). This approach has been implemented in an implicit finite element code in order to predict the strength of composite structures, exhibiting different levels of complexity (unnotched plates, open-hole plates) and subjected to complex loadings (membrane or bending loadings). All the 13 Test Cases of the third world-wide failure exercise have been solved.

A method to determine composite material residual tensile strength in the fibre direction as a function of the matrix damage state after fatigue loading

“…Nothing demonstrates that these two types of damage mechanisms give rise to a similar reduction in residual strength in the fibre direction. A more general approach would then consist in defining the residual strength as a function of several damage variables associated to the different damage mechanisms (separating micro-scale phenomena and meso-scale phenomena) as proposed in multi-scale models [13,42]. However, identifying such a function requires completing the proposed experimental procedure with a first test where damage is produced by a transverse loading and a second test where damage is produced by a coupling between transverse and shear loading.…”

Validation and modeling of aeronautical composite structures subjected to combined loadings: The VERTEX project. Part 1: Experimental setup, FE-DIC instrumentation and procedures

“…Several approaches are based on continuum mechanics and damage mechanics: the ''mesomodel" developed initially at LMT Cachan [4] and the ONERA model (ranked ''best model" in WWFE 3 [5,6]), among others [7,8]. The authors of these articles (the present article and its second part) initially developed the Discrete Ply Model method to deal with out-of-plane issues such as low energy impact [9,10] and pull-through [11].…”

Failure of Fiber-Reinforced Composites

“…While this exercise is still going on, first results of the blind predictions indicate a clear diversity of predictions regarding the effects of ply thickness, the stacking sequence and interaction of existing cracks with neighboring layers, in particular to induce delamination [79]. However, a larger tendency is seen to use finite element modeling [80][81][82][83][84][85][86] and micromechanical approaches [80,81,85,[87][88][89]] to obtain failure predictions. A specific challenge for the existing theories is the forward prediction of crack density and crack saturation of interfiber cracks.…”