Conical impact fragmentation test (CIFT)

Abstract

Conical impact fragmentation tests (CIFT) were conducted to develop and demonstrate an experimental capability for uniformly inducing controlled fragmentation in structural metals. The setup involves a conical specimen impacting a mating conical target (similar in geometry to a funnel) at nominal velocities of 1–2 km/s. Three experiments were conducted as proof of concept to characterize the fragmentation behavior of 1018 steel. Photonic Doppler velocimetry probes on the free outer surface of the target cone allow for validating simulations that can indicate strain uniformity in the target cone. Overall, experimental results demonstrate CIFT to be a feasible method to evaluate fragmentation behavior. The conical geometry produces consistent and bounded strain rates that are maintained for at least 10 microseconds. Furthermore, when compared with other laboratory techniques, the CIFT technique is shown to be more ideal than sphere-on-plate impact (SPI) and more tunable than cylinder expansion (CYLEX), and so is a promising fragmentation characterization tool.