Mode I fracture initiation in limestone by strain energy density criterion

The critical mode I stress intensity factor obtained from fracture tests on laboratory specimens is often used as fracture toughness in brittle and quasi-brittle materials. However, considerable variations in the experimental results reported for a given material may suggest the dependency of critical mode I stress intensity factor on the geometry and loading conditions of the test specimen. The main purpose of this paper is to study the effect of T-stress on the critical mode I stress intensity factor of brittle and quasi-brittle materials. The minimum strain energy density criterion was revisited to take the effect of T-stress into account. The results obtained were then compared with a series of experimental results reported for limestone. It is shown as a result that the formulation presented in this paper is capable of estimating the experimental results in a satisfactory manner. (c) 2011 Elsevier Ltd. All rights reserved.