Experiment and finite element simulation of X-type shear fractures from a crack in marble

Abstract Laser holographic interferometry is used to measure the out-of-plane displacement field in the uniaxial compression testing of a marble plate with an inclined crack. The experiment shows that near the tips of the crack, tensile fractures first occur; they propagate curvilinearly, bend toward the axial direction and become stabilized. This agrees well with the usual theory. However, if the crack is an open slot, as the compressive load increases, X-type shear fractures appear near the tips of the slot, propagate in the direction opposite to the tensile fractures and lead to final rupture of the specimen. This phenomenon can be related to the strain softening behavior near the tip of the slot. A mathematical model using finite element analysis for strain softening of elastoplastic material is used to simulate the process and obtain the same result. If the crack is a closed cleavage, the rupture takes place as X-type shear fractures starting from the boundary of the plate.