FE macro/micro analysis of thermal residual stresses and failure behaviour under transverse tensile load of VE/CF – fibre bundle composites

This paper presents a finite element analysis of a transverse fibre bundle test (TFT) using carbon fibres embedded in a vinylester urethane hybrid matrix. The evolution of thermal residual stresses, due to the cooling phase of the curing process of the model-composite and the subsequent mechanical load transverse to the fibre direction, has been investigated. The applied displacement coupling technique allowed to transfer the boundary conditions from a global model (macro model) via an intermediate model to a micro model. As a result it could be shown that the larger fraction of the total stress build up until failure occurred was due to the implicated thermal residual stresses. The micro model offered more accurate and detailed results with regard to the stress distributions on critical locations such as the fibre/matrix interface region. Generally, the results of the global model were in good agreement with the experimental data obtained. Further, the parabolic failure criterion based on experimental data of the pure matrix was used to predict time and place of failure initiation.