Modelling Failure Mechanisms in Composites Subjected to Impact and Post-Impact Compression

摘要

Composites subjected to low-velocity impact are prone to abrupt failure duringpost-impact compression. Impact reduces the compressive residual strength ofcomposites significantly. In many cases, compression after impact (CAI) strength isthe critical factor in design. This paper presents an integrated finite element modelthat aims to predict CAI strength without simplifying or idealizing the damage dueto the impact event. Composite laminates impacted at energy levels of 1.6 J, 6.5 Jand 17 J are subjected to compression to failure. The CAI strength values as well asdelamination and damage patterns correlate well with experiments taken fromliterature. It was found that failure during post-impact compression is governed bylocal buckling, which triggers damage growth. An increase in mode ІІ fracturetoughness can essentially reduce delamination size induced during impact,consequently improving residual strength by delaying the onset of buckling (andtherefore damage growth) during compression.