Finite element simulation of buckling-induced failure of carbon fibre-reinforced laminated composite panels embedded with damage zones

This work is concerned with the buckling-induced failure prediction of aerospace grade carbon fibre-reinforced laminated composite panels embedded with pre-assumed damage. Fibrous composites are being broadly used in aircraft and aerospace vehicle components. However, a major drawback in widespread use is their susceptibility to drop tool impacts and ground equipment collisions. Such incidents could inflict invisible internal damage and delamination that divides laminate into sub-laminates of lower bending stiffness/resistance to buckling load that might result in catastrophic consequences during later operations. This situation is a major concern for aircraft/aerospace industry and necessitates thorough understanding of damage tolerance capabilities of structural members for safety of human lives and structural assets. Extensive studies, based on experimental testing, were conducted on the topic. Since physical testing consumes time and resources, generate limited data, and lack in ply level effect of mixed-modes buckling hence development of a computational model is required. The present study consists of simulation models developed using ABAQUS™ software. Impact-induced damage was introduced as an area of reduced stiffness (soft-inclusion) or hole. Overall damage zones of known size and shape were inserted at various locations in the volumes of various laminates to predict critical buckling load based on global and local buckling with emphasis on mixed-mode buckling. Simulated cases of single and multiple damage zones/holes, switching and coupling of local-global buckling modes were investigated. Damage size, location, type, and penetration depth against critical buckling load and mode shape were investigated. The critical buckling load is found to correlate well corresponding to soft-inclusions to predict ply-level failure. Selected results of eight-, sixteen, and twenty-four ply laminates were compared against the data available in the literature and found to be in agreement up to 90%. The model could also be useful to efficiently study various lay-ups, loading, and material properties for the similar cases.