The mechanism of fracture coalescence in compression—experimental study and numerical simulation

Abstract The mechanism of fracture coalescence is reported from uniaxial compression of gypsum samples with two open or closed cracks. Coalescence can be caused by tensile failure, shear failure or mixed tensile and shear failure. In this paper, the coalescence observed in the tests is modeled numerically by using a modified G -criterion and displacement discontinuity method (DDM). The numerically predicted path and critical load of coalescence are in good agreement with the experimental results. It is also unveiled by this study that mode II failure is the key reason for the coalescence between two non-overlapping cracks.