Influence of open joints on blasting damage and crack propagation of PMMA

In order to study the influence of open joint on blasting damage and crack propagation, plexiglass (PMMA) specimens with open joints were designed to carry out a study using a digital laser dynamic caustic experimental system. The results showed that the crack could not pass through the opening joint. The joint could promote the destruction of the medium between the borehole and the joint. Affected by the reflected stress wave at the joint, the crack was no longer simply subjected to tensile stress. Instead, it was influenced by the combined action of tensile stress and shear stress. The fracture type of crack changed from Type I to mixed Types I and II. During the reflected stress wave stage, the crack growth rate and intensity factor of dynamic stress increased.