The Design, Construction and Testing of Unique Operated Hopkinson Split Pressure Bar System

Abstract

This study involves the design and construction of a split Hopkinson pressure bar apparatus as well as an investigation of the effects of high speed impact on two types of composite materials. A unique spring operated striker mechanism is designed and tested, thus introducing a major simplification to SHPB design requirements. Impact testing velocities of up to 25m/s are achieved. Samples results of impact tests on unidirectional glass fiber and unidirectional carbon epoxy are presented with a comparison between them. The effects of strain rate on specimen properties (compressive stress and strain) are determined. A strain rate range of 107-252 /s is achieved using impact speed range of 3.39-9.98 m/s for the unidirectional glass fiber composite. The corresponding ranges for the unidirectional carbon composites were 485-951/s strain rate and 6.68-13.28 m/s impact velocity. The results indicated that the max stress and strain are all increased with increasing the strain rate for both types. The carbon/epoxy showed higher properties compared with the glass/epoxy. The carbon samples sustained higher range of strain rate resulting in higher stresses and strains.