Dynamic shear behavior and fracture characteristics of corrugated multi-interface Q245R/TA1/1060Al composite plate by explosive welding

Abstract

Dynamic shear fracture is a typical failure mode under high-velocity impact, and the performance of explosively welded multilayer composite plates largely depends on the strength of the bonding interfaces. Therefore, elucidating the differences and anisotropy behaviors of the interfaces within Q245R/TA1/1060Al composite plate is crucial for structural optimization. An optimized S-shaped specimen was prepared, and based on previous studies, the dynamic shear stress intensity factor (DSSIF) calculation formula for the specimen was revised. It was assumed that secondary cracks were initiated from the notch tip of the S-shaped specimen. The DSSIF for these secondary cracks were determined using the finite element contour integral method. Subsequently, as the secondary crack length approached zero, the DSSIF for the S-shaped specimen was obtained. Combining digital image correlation (DIC) with Split Hopkinson pressure bar (SHPB) systems to study the dynamic shear properties and failure mechanisms of multi-interface under varying orientations. Fracture macroscopic morphology and microstructural characteristics were characterized using 3D surface profiling and field emission scanning electron microscopy (FESEM). The results demonstrated that the S-shaped specimens exhibited shear strain concentration and fracture failure at the predetermined interfaces, which confirmed that it was suitable for dynamic shear experiments. Although the dynamic shear fracture toughness (DSFT) of TA1/1060Al interface was substantially lower than that of TA1/Q245R interface, both interfaces showed significant positive strain-rate dependence. The distinctive wavy interfacial morphology formed by explosive welding resulted in anisotropic dynamic shear properties of the bonding interface. Specifically, the mechanically interlocked structure along the 0° sampling orientation contributes to significantly enhanced DSFT than 90° orientation. Additionally, the fracture surfaces morphology revealed an inverse correlation between impact velocity and fractal dimension values. Concurrently, the fracture surfaces identified by FESEM analysis exhibited mixed ductile–brittle failure modes. These findings offer insights for optimizing structural design in composite plate applications.