Comparison of Methods for High-Pressure Dynamic Yield Strength Measurement

The four widely used methods to measure the high-pressure dynamic yield strength of solids, including Asay-Chhabildas (AC) method, lateral stress gauge (LSG) method, pressure-shear (PS) method, and X-ray diffraction (XRD) method, were analyzed in the present work. According to the difference of instant strain rate, the yield strengths defined by different methods hereinbefore are divided into two types: one is with high strain-rate, including the data from PS, XRD, as well as Y=Y=2c from AC method; the another is with zero strain-rate, including the data from LSG, and Y=Y=2H from AC method. The yield strengths of various aluminum and its alloys from publications were compared. Results show that the data from PS, XRD, and Y=Y=2c from AC method are approximately consistent, the data from LSG method, however, are obviously higher than the Y=Y=2H from AC method, and even higher than the data with high instant strain-rate. Further work is needed to determine the cause of the abnormal data from LSG method. Results also show that the Steinberg-Cochran-Guinan (SCG) model is strongly affected by the initial yield strength of materials, and a modified model is needed to describe the behavior of yield strength under high pressure or stress.