Core Deformation of Sandwich Composites under Blast Loading

During blast loading, the core of a sandwich composite demonstrates complicated stress/strain behavior. The shear stress/strain in the core is the primary consideration. Though the shear strain profile is non-linear, the transverse strain in the core is generally modeled with a linear or constant profile in numerical simulation. However, recent numerical studies have found that the transverse strain in the core also has a highly non-linear profile through the thickness. This is important in understanding the mechanism of pulse mitigation in sandwich composites. To date, no experimental investigations have been done to visualize the strain profile in the core of sandwich composites subjected to blast loading. In this paper, the high-speed 3-D Digital Image Correlation (DIC) technique was utilized to characterize such strain profiles. The real-time deformation images of the core material in a sandwich panel were captured by a high-speed photography system. The strain profiles and histories were calculated from these real-time images using DIC technique. These results were carefully analyzed and discussed.