Effect of Oblique and Off-Center Impact on CFRP Laminate Under Low Velocity Impact

Composite structures are widely used in various engineering sectors, such as ships, aerospace, and automobiles due to their specific mechanical properties. In service operations like maintenance (dropping of tools), these structures are often subjected to low velocity impact (LVI), which leads to a decrease in the strength of laminates. Parameters such as fiber orientation, stacking sequence, boundary condition (BC), impactor geometry, and angle of impact affect the performance of composites. Therefore, it is essential to study the response of composites under LVI for different parameters. The role of fiber orientation and geometrical factors (oblique impact, impactor geometry, and off-center loading) on the dynamic response of composites under LVI needs to be investigated. The initial section of the research validates the presented numerical simulation results of reference layup A i.e. [0₂/45₂/90₂/45₂]_s with previously published experimental results. In the second part, finite element analysis to study the effect of normal and oblique impact and the effect of off-center loading on three different combinations of CFRP layups under LVI with three nose geometries of the impactor are presented. Simulation performed on CFRP T700GC/M21 material for normal and 45° oblique impacts to study the dynamic response using Abaqus/Explicit modeling software. This parametric study shows that the effects of fiber orientations, oblique impact, and impact location with different geometries of impactors plays an essential role in designing composite structures. Under oblique impact, layup B i.e. [0₂/90₂]_2s exhibits the highest fluctuations in all impactor geometries, which signify intra- and interlaminar failure. Additionally, the hemispherical impactor for layup A shows smooth curves and less fluctuation under off-center loading.