Numerical simulation of the radial inertia effect on cement mortar in SHPB test

Cement mortar, of which the mechanical properties are affected by the confining pressure and other factors, is a kind of material sensitive to strain rate. Many scholars believe that the dynamic compression strength of concrete-like material is enhanced by the effect of lateral inertia of specimens in split Hopkinson pressure bar (SHPB) test. Meanwhile the lateral friction between bar and specimen and the hydrostatic pressure on the transversal end faces can enhance the lateral inertia. To investigate the relationship among the enhancement of dynamic compression strength, the hydrostatic pressure in the transverse and the axial strain acceleration of the elements along the central axis, ANSYS/LS-DYNA is used to stimulate the dynamic mechanical properties of 37 mm diameter and 20 mm thick mortar specimens in SHPB test. The test results show that the hydrostatic pressure in the transverse has a fluctuation distribution in the test, which leads to the enhancement of axial compression strength while the additional axial stress caused by the acceleration of the axial elements is much less than the enhancement of the dynamic compression strength.