Influence of simulation parameters in the combined loading compression testing of CFRP specimens

In this paper a sensitivity study of a FEM model representing a carbon/epoxy composite material tested in Combined Loading Compression (CLC) is presented and the results are compared to experimental results. The present study aims to simulate the failure of composite materials when subjected to compression and crush loading conditions. This is required as a first step of a Building-Block Approach towards full-scale modelling of complex structures. In the experimental part of the work, a laminate panel was manufactured with carbon unidirectional prepreg (Deltapreg UTS-300-DT120-37EF) in a cross-ply, balanced and symmetric stacking sequence, cured in autoclave at 120°C and 5 bar for 90 min. A number of six samples, extracted from the panel, were tested in compression following ASTM D6641/D6641M-16. Numerical simulations have been implemented by means of the commercial software, ESI-VPS PAM CRASH. Boundary conditions, specimens' dimensions and material properties emulated real test conditions. A sensitivity study was performed on critical simulation parameters: the effect of mesh size and number of shell surfaces representing the composite stacking sequence was initially investigated. Furthermore, the specimen failure mode was inspected by the application of TIED links between the composite plies. Numerical results have been compared with experimental data and the comparison provided references for testing scale-up in the Building-Block Approach.