Hopkinson bar experiments as a method to determine impact properties of brittle and ductile materials

Abstract

Split Hopkinson bar experiments are fundamental test arrangements to determine elastic, plastic, and fracture properties of materials under high strain rates. A specimen is considered to be in a well‐defined state of uniaxial stress, and depending on the specific device, limit loads or high strains can be achieved through purely elastic loading in the bars where there are no shock waves present. Variations of the conventional Hopkinson bar procedure allow determining of the dynamic fracture toughness of brittle materials. Here, the results of dynamic Brazilian tests on ultra‐high performance concrete are compared with the results of spallation experiments that simultaneously allow for the determination of the specific fracture energy. Similar experiments are performed for water ice. In addition, the strain rate dependence of the plastic hardening of a medium carbon steel is investigated. The yield stress is determined at strain rates up to 1300s−1.