Laser Measurement Technique in Split Hopkinson Pressure Bar

The split Hopkinson pressure bar (SHPB) is a commonly used technique to measure the stress-strain of materials at high strain rate. Using the strain records in the input and output bars, the average stress-strain and strain rate in the sample can be calculated by SHPB formulas based on the one-dimensional wave propagation theory. The accuracy of a SHPB test is based on the assumption of strain uniformity within the sample, which, however, is not always satisfactory in a real SHPB experiment because of some unavoidable negative factors, such as the effects of friction and sample size. One of the new measurement techniques is a non-contact method using Laser. In this technique each laser beam is divided into two independent sections to track the displacement of the input and the output bars. In this study, we intend to investigate the possibility of using laser for measuring strain in SHPB test and determined whether it is applicable to a wide range of materials. In this regard, we compare the strain of the sample with laser measured strain on two soft and hard samples, using numerical simulation in ABAQUS software.