An Impact Induced Damage in Composite Laminates with Intra-layer and Inter-laminate Damage

Low velocity experimental and numerical study have been performed on four layer [0°/90°]s and [90°/ - 45°/+ 45°/0°]_s composite laminates at three different energy levels to observe the damage mechanism and delamination pattern. Experiments were performed using a drop weight testing machine as specied in ASTM D5628 FA while numerical analysis was executed using Abaqus Explicit. Hashin failure criteria is used to capture the intra-layer damage modes while surface based cohesive behaviour with quadratic stress failure criteria was used to predict delamination. It was observed from the results that matrix cracking occurred first followed by the delamination. The tensile fiber failure mode triggered at the peak force after which the damage energy stabilises to a particular value. For [0/90]s laminate, larger peanut shaped delamination profile is noticed on the third interface from the impact face along the 0°fiber direction. However, [90/ 45/+ 45/0] sequence profile was oriented along -45°laminate in the second interface from the impact face. The size of profile increases from impact side interface to non-impact side interface due to the increasing flexural stresses. The area of the profile tends to increase with increasing energy and this increase is dominated by the length rather than width. Results of numerical simulations were found to be in good agreement with the experimental results.