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Modelling Failure Mechanisms in Composites Subjected to Impact and Post-impact compression

M.R. ABIR, T.E. TAY and H.P. LEE


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

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