Notch sensitivity and damage mechanisms of glass mat reinforced polypropylene

Notch sensitivities of two structurally different glass-mat reinforced polypropylene materials (GMT) were investigated. Center hole notches in tensile specimens were used in the tests. The results show that the short fiber material has higher unnotched strength, but also higher notch sensitivity compared to a swirled mat material, Reasons for this are discussed, focusing on microstructural differences. Predictions from four different failure criteria were compared with the experimental notched strength data. The point stress and damage zone criteria were found to give the best descriptions.