Effect of V-groove and semi-circular core surface configurations on mechanical properties and failure mechanisms in composite sandwich panels

Sandwich composite materials, which are widely used in the field of renewable energy, have attracted considerable attention in recent years. Sound enhancement strategies for the core or skin/core bond can substantially improve the mechanical properties of composite sandwich structures. This study investigated the effect of core surface processing configuration on the strength and failure behaviors of composite sandwich structures. Composite sandwich panels were fabricated using the vacuum-assisted resin infusion process and subjected to shear, edgewise compression, and peel tests. The experimental findings demonstrated that, relative to pure foam core sandwich panels, the V-shaped groove (VG) and semicircular groove (SG) core sandwich specimens exhibited a moderate improvement in shear modulus, shear strength, edgewise compression capacity, and peel strength. During shear loading, pure foam core sandwich panels were highly susceptible to skin/core debonding. In contrast, the failure site in VG and SG core sandwich panels was located immediately adjacent to the core region. This deviation could be ascribed to the influence of rigid resin columns, which effectively alter the load-transfer path from the skin/core interface to the core itself. Under edgewise compression, pure foam core sandwich panels experienced global buckling failure. Conversely, VG and SG core sandwich panels were more likely to endure shear buckling followed by core shear failure. Under peel loading, all sandwich specimens failed by means of separation at the skin/foam interface and resin/skin interface.