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

An understanding of stress patterns in rock breakage tests has continually proved to be problematic and the comparison of a theoretical prediction wit h that which occurs in reality is often difficult. This paper reports on th e use of Thermal Stress and High Speed Camera Analysis to observe regions o f varying stress intensity and ascertain the exact location of subsequent c rack propagation. In particular these techniques have been used to study Th ree Point Bend and Ring-loaded Strength rests on rock samples. The behaviour of rest specimens was studied using the 'Deltatherm' thermal stress analyser and different stress regimes were identified. The same spec imens were then studied using the High Speed Camera to observe crack growth . These independent observations confirmed that the failure mechanisms in b oth rests were inherently tensile in nature, as crack propagation was obser ved to originate from areas of induced tension. (C) 2001 Elsevier Science L td. All rights reserved.