The use of high speed image and stress analysis for the evaluation of tensile based breakage tests

Abstract

An understanding of stress patterns in rock breakage tests has continually proved to be problematic and the comparison of a theoretical prediction with that which occurs in reality is often difficult. This paper reports on the use of Thermal Stress and High Speed Camera Analysis to observe regions of varying stress intensity and ascertain the exact location of subsequent crack propagation. In particular these techniques have been used to study Three Point Bend and Ring-loaded Strength tests on rock samples. The behaviour of test specimens was studied using the ‘Deltatherm’ thermal stress analyser and different stress regimes were identified. The same specimens were then studied using the High Speed Camera to observe crack growth. These independent observations confirmed that the failure mechanism in both tests were inherently tensile in nature, as crack propagation was observed to originate from areas of induced tension.