Fracture mechanisms in rock-like Bi-material beams under mode I loading: effects of crack location and thickness ratio

Understanding the fracture behavior of bi-material systems is crucial in rock mechanics where material heterogeneity and interfacial discontinuities can significantly affect crack propagation. This study experimentally investigated the crack propagation mechanisms in layered specimens composed of two cementitious materials with deliberately contrasting mechanical properties. Six bi-material configurations were tested under three-point bending using pre-notched beams, with variations in layer thickness and initial notch location. Single-material tests were also conducted to determine the uniaxial compressive strength, tensile strength, and fracture toughness of each constituent material. The results demonstrated that notch location and relative layer thickness significantly influenced fracture behavior. Cracks originating in the stiffer material typically propagated directly across the interface. In contrast, cracks initiated in the weaker material often showed deflection or staged propagation. Load–displacement curves reflected these differences, with specimens containing notches in the weaker material exhibiting lower peak loads, and in some cases, multiple load peaks. The experimental findings contribute to a deeper understanding of interface-controlled fracture behavior in rock-like composites and provide valuable data for validating future numerical simulations.

کلیدواژه ها:

Bi-material interface ، Rock-like material ، crack propagation ، Three-point bending ، Fracture Toughness