Confronting Numerical Simulations via Combined XFEM–Level-Set Methods with Experimental Three-Point Bending Tests

This study presents a theoretical framework and numerical simulations for crack initiation and growth in cohesive materials within two-dimensional domains. A cohesive-zone model, implemented with the Extended Finite-Element Method and a level-set description, yields load–deflection curves. Experimental three-point bending tests on concrete specimens provided fracture energy, Young’s modulus and tensile strength values, which were used as inputs. Numerical and experimental load–deflection responses showed strong agreement, with fracture energy predictions within 5% of measured values. A parametric analysis revealed that increased fracture energy corresponds to larger areas under the load–deflection curves, while higher tensile strength raises peak load values. Moreover, the simulations successfully captured snap-back behavior in low-fracture-energy materials, which is difficult to detect experimentally.