Numerical analysis of the defects presence on the fracture behavior of a polymethyl methacrylate (PMMA)

Poly methyl methacrylate (PMMA) is a brittle polymer with low resistance to cracking. Its mechanical properties include a young’s modulus of 3240 MPa, Poisson’s ratio of 0.35, yield strength of 70 MPa, fracture toughness (KIc) ranging between 0.8 and 1.2 MPa·m1/2, ultimate tensile strength of 72 MPa, and density of 1190 kg/m³. When subjected to mechanical stress under quasi-static loading conditions with applied stress levels of 10, 15, 20, and 30 MPa, a cracks appear, these cracks are generally responsible for the damage and can lead to premature failure. This study aims to analyze the resistance to cracking of polymethyl methacrylate (PMMA) using finite element method (FEM). Various scenarios are considered, including the effects of notches, cracks emanating from notches, notch-crack interactions, a central crack, and crack-crack interactions. The material behavior is evaluated in terms of stress concentration factor (Kt) for notches and stress intensity factor (KI) for cracks, focusing on the most critical modes of damage propagation (Kt) and (KI). The results provide insights into the influence of defect geometry and their interactions on PMMA, offering guidance for engineering design optimization.