The Effect of Specimen Dimension on the Results of the Split-hopkinson Tension Bar Testing

The split-Hopkinson tension bar (SHTB) has been used widely to determine the dynamic characteristics of materials. Despite of its application, the tensile test specimen has not been standardised yet, whereas its dimension could affect the test results. Therefore, it is necessary to study the consistency of SHTB results by varying the dimension of its specimen. This paper examines whether consistent results can be achieved from three case studies of SHTB in a direct method. The study was conducted by numerical simulation using LS-DYNA®. A dumbbell-shaped specimen was designed similar to the standard specimen on ASTM A370. Pressure bars were made of Maraging steel with 14mm in diameter and a flange with thickness of 5mm was used, while the specimen was made of 1006 mild steel. The simplified Johnson-Cook was used as the constitutive material model. Three case studies were carried out. The first case study used a group of specimens with thesame gage length of 6mm and varied diameters; the second case study used a group of specimens with the same diameter of 8mm and varied lengths; and the third case study used a group of specimens with the same gage length of 8mm and varied diameters. Based on the results of all case studies, the specimen's length-to-diameter ratio (L/D) of 0.75 generates a good stress-strain behavior.