CRITICAL-APPRAISAL OF LIMITING STRAIN RATES FOR COMPRESSION TESTING OF CERAMICS IN A SPLIT HOPKINSON PRESSURE BAR

The split Hopkinson pressure bar (SHPB) is being widely used to determine the dynamic compressive strength of ceramics and ceramic composites. However, extreme caution needs to be exercised while testing these high-strength ceramics at high strain rates. The highest strain rate at which ceramics can be tested using an SHPB without violating the underlying assumptions is found to be in the range of 2500-3000/s. It is also shown that at very high loading rates, dispersion in the transmitted pulse can lead to discrepancies in measuring the dynamic failure strength of ceramics.