| High strain-rate tests were performed on LM-1 using a Split-Hopkinson Pressure Bar (SHPB) to investigate effects of L/D ratio and annealing. An ultra high-speed camera was also employed to record the deformation and failure processes of LM-1. The as-cast (i.e. amorphous) specimens exhibited a reduction in peak stress with reduced L/D ratio and failure at the specimen-insert interface, indicative of stress concentrations due to the difference in the specimen and insert diameters, while the annealed specimens exhibited extensive fragmentation.; The stress concentrations in the specimen motivated simulations using LS-DYNA to design new inserts. A tapered insert design was chosen to reduce stress concentrations, and as-cast and annealed specimens were tested. Strain gages were also attached to ascast specimens to determine the elastic stress-strain response. As-cast and annealed specimens with tapered inserts exhibit failure in the gage section, while the strain gages recorded no reduction in peak stress with reduced L/D. |
