Publication: Numerical and experimental studies of a different striker bar shape for the achievement of a constant strain rate in shpb tests
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Date
2023-07-14
Authors
Mohamad Amirul Hafizie bin Izham
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Abstract
The Split Hopkinson Pressure Bar (SHPB) test is a widely used experimental technique for investigating the dynamic behaviour of materials under high strain rates. One of the challenges in conducting SHPB tests is achieving a constant strain rate throughout the duration of the test. Different strain rates often result in different stress-strain responses, which makes comparative material analysis difficult if the strain rate is not constant. The accuracy of the experiment result also can be disturbed when the strain rate is not constant. This research focuses on studying the effectiveness of a different striker bar shape in attaining a constant strain rate in SHPB experiments. The new striker bar design, which is conical in shape with a spherical end and tapered end surface, has been developed and compared with the conventional flat end striker bar. The striker bar used to impact the specimen which is copper to study the effect toward achieving constant strain rate in SHPB test. The copper was impacted with three different pressures for each striker bar design. In this study also, we develop a finite element model (FEM) for each striker bar design to study the wave propagation of different shape striker bar and to identify whether the wave produced in the SHPB test can be replicated. The results show that the new striker bar design has a significant impact on achieving a constant strain rate in this SHPB test. The new design effectively reduces the strain rate variations for certain pressure throughout the duration of the test compared to the conventional striker bar shape. The magnitude of the stress strain curve graph for the new striker design are different and much lower compared to the conventional striker bar design. The new striker bar design also has a lower strain rate value compared to the conventional flat end surface striker bar. In conclusion, different shapes of striker bars in SHPB tests have a huge impact on achieving constant strain rate. The simulation for new striker bar design have encounter an error due to several factor and cannot be used to determine the similarity of the experimental and simulation results.