Notch strength and notch sensitivity of polymethyl methacrylate glasses

In this study, attempts are made to obtain the approaches for quantitatively evaluating the notch sensitivity and the notch strength of polymethyl methacrylate (PMMA) glasses. Tension tests show that the unoriented PMMA glass is a low-ductility material and the oriented PMMA glass is a high-ductility one, and the orientation of PMMA glass greatly increases the fracture ductility. The notch sensitivity of PMMA glasses can be evaluated by the so-called notch sensitivity factor, which can be predicted from tensile properties. Test results and analysis show that the notch strength of PMMA glasses can be expressed by the equation for notch strength and predicted from tensile properties for the notched elements of PMMA glass with any given stress concentration factor. The orientation of PMMA glass decreases the notch sensitivity and increases the notch strength. It should be noted that PMMA glasses have higher notch sensitivity and lower notch strength than those of ductile metals because of the very low-elasticity modulus of PMMA glasses. It also shows the possibility of predicting the failure criteria with given survivability for PMMA glass notched elements in this paper.