Measurement of lateral stress and spall strength in ceramics

摘要

The deviatoric response of brittle materials has been the subject of much recent interest. Several plate impact studies have employed embedded gauges to directly monitor the lateral stress within the sample. Under certain conditions the wave profile measured in this way in ceramics exhibits a two step structure. This has been attributed to a damage front travelling behind the shock. It has been shown for alumina ceramics that the second rise in stress is not evident when a thin cover plate is mounted on the front of the target or a symmetric impact experiment is performed. In this work spall strengths are monitored at different distances from the impact face in order to look for evidence of a failure front within the ceramic target. Such an approach has previously been successfully employed to detect these features in glasses.