Design and numerical simulation of a new sandwiched sphere structure for ballistic protection

Sphere structures for ballistic protection have rarely been studied. In this paper a novel unit cell, called Square Based Pyramid Unit Cell (SBPUC), is created as a fundamental building block of sphere structures for the purpose of ballistic protection. Although it has been proved by the other authors that the arrangement of spheres in a tapered chain is an efficient way for impact energy absorption (Sokolow A, Pfannes JM, Doney RL, Nakagawa M, Agui JH. Absorption of short duration pulses by small, scalable, tapered granular chains. Appl Phys Lett 2005;87:1–3), it is very difficult to convert this 1D concept to 3D application in reality with arbitrary tapering angle. The adoption of SBPUCs may provide a good solution. In this research, the core of a sandwiched sphere structure is build with such SBPUCs and is characterized with increasing sphere diameter, decreasing sphere thickness, and increasing sphere cap thickness. From the numerical simulation results with ABAQUS/Explicit, the sandwiched sphere structure can absorb at least 11.6% more impact energy compared with the monolithic plate with the same area density. This study might provide a potential armor design platform which makes further performance improvement possible by optimizing the large parameter space associated with material selection and structure design.