Stain-rate effects on the dynamic compressive strength of concrete-like materials under multiple stress state

This paper first reviews the development and relevant issues in relation to the strain rate effects on the compressive strength of concrete-like materials. For different characteristics of strain-rate effects on the dynamic compressive strength of concrete-like materials under various stress states, it reveals the significant discrepancies in the measured dynamic increase factors (DIF) under different loading paths. At high strain-rate loading, the test specimen based on the initial 1D-stress state gradually evolves to a multiaxial one due to the increasing lateral confining pressure caused by the lateral inertia effect. The traditional split Hopkinson pressure bar (SHPB) test cannot obtain the genuine DIF data under real 1D-stress state at high strain rates. The strength models based on the direct adaptation of the experimentally measured DIF using SHPB overestimate the dynamic strength of these materials. Considering the loading-path dependence of the strain-rate effect, this study extends the DIF model depending only on strain-rate to a more general DIF model depending on both the strain-rate and the stress state, which is then implemented into the Drucker-Prager strength model. Numerical SHPB tests are conducted on samples with free and constrained boundaries. The comparison between test data and numerical predications shows that the proposed DIF model can describe the stress state dependency of the strain rate effect, and hence can predict the dynamic compressive strength of concrete-lime materials more accurately. The present study is of great significance for correctly applying SHPB technology to determine the dynamic compressive strength of brittle materials. © 2022 Explosion and Shock Waves. All rights reserved.