Influence of Disc Specimen Configuration on Its Three-Dimensional Dynamic Stress Balance

Abstract EN

In order to investigate the dynamic stress balance of different configurations of rock specimens, three-dimensional finite element models of SHPB were established.

Five types of configuration disc specimens with a diameter of 75 mm and a thickness of 30 mm were impacted at a speed of 5 m/s using a special-shaped bullet.

The propagation laws of stress wave on the contact surface of the specimen-bar and the inside of the specimen were analyzed, and the time history of the stress balance factors at different positions of the specimen was obtained.

The results show that the amplitudes of the transmitted waves corresponding to the five types of disc specimens with different configurations have obvious differences, and the stress propagation in the specimen has three-dimensional characteristics.

According to the ease of achieving stress balance, the five configuration specimens are ordered by notched semicircular bending disc, flattened Brazilian disc, cracked straight-through flattened Brazilian disc, Brazilian disc, and cracked straight-through Brazilian disc specimen.

Among them, only the first three configurations of the specimen reached the stress balance.

The dynamic stress balance is affected by the disc loading mode, end contact conditions, the presence of prefabricated cracks, and disc thickness.

In addition, as the disc loading end is a processed platform, it is beneficial to achieve stress balance.

Prefabricated cracks are not conducive to achieving stress balance.

The loading method of the notched semicircular bending disc is more conducive to achieving stress balance.

This research has a certain guiding significance for selecting suitable specimen configuration and research methods to carry out rock dynamic fracture experiments.