The split Hopkinson pressure bar apparatus is used in studying the high strain rate compressional behavior of 6061-O aluminum alloy. Circular disks of approximately 6 mm in thickness and 10 mm in diameter are tested at average strain rates of 10 3 to 3 × 10 3 sec −1. Transient wave forms are measured using a four-channel signal conditioner, strain gages, and a digital oscilloscope. In order to obtain the dynamic stress-strain relationship, uniaxial elastic stress wave theory is utilized in analyzing the measured signals. Quasi-static tests are performed using an MTS machine, with samples being tested at a strain rate of 3 × 10 −4 sec −1. In addition, the MARC finite element code is used in simulating the transient response of the input bar, output bar, and specimen following impact by the striker bar at a specified velocity. Experimental results reveal that the dynamic yield stress of 6061-O aluminum alloy increases under high strain rate loading conditions. When the dynamic yield stress is considered in the simulations, code simulated wave forms agree well with the measured test results; verifying the fact that the dynamic constitutive relationship obtained by simple one-dimensional stress wave theory adequately describes the high strain rate behavior of 6061-O aluminum alloy.
Read full abstract