Shear localization in pore collapse as a damage mechanism under shock compression

In this work, we explore the role of porosity under shock compression, to drive damage or failure in the loaded material. Shear localization, resulting from pore collapse is suggested and studied as the damage mechanism. Ti-6Al-4V specimens, with cylindrical and spherical pores were manufactured using additive manufacturing (AM). The specimens were loaded by plate impact using a gas gun, and a soft catch set-up enabled their post-mortem analysis. Under plate impact experiments conducted at shock pressures of 3-8 GPa, the 1-2 mm voids demonstrated collapse and the evolution of shear bands (SB), emanating from the void surface. Varying the impact velocity and corresponding impact pressures, different states of SB evolution were studied. Specimens with multiple pores allowed also to examine the interaction of localization between adjacent pores, creating extended states of joint damage. Numerical simulations were used to reproduce the measured phenomena, and extent the discussion to real micro-meter sized pores at elevated pressures.