Abstract
In order to study the dynamic fracture toughness of composite materials from a viewpoint of fracture mechanics, the dynamic fracture toughness, the absorbed energy and the velocity of crack propagation at initiation of crack growth were determined on glass fiber reinforced polycarbonate as a function of temperature by using a Charpy tester loaded with various instruments.
The results obtained are as follows: The dynamic fracture toughness and the absorbed energy for glass fiber reinforced polycarbonate increase with an increase in temperature. The increasing rate for the specimen of 30wt% fiber content, in which the mechanical and thermal properties are controlled by those of glass fiber, is smaller than that for the specimen of 10wt% fiber content, in which they are controlled mainly by those of matrix. The velocity of crack propagation decreases with an increase in temperature. The decreasing rate for the specimen of 30wt% fiber content is smaller than that for the specimen of 10wt% fiber content. By introducing a modified factor, φ, which represents the dependence of relative crack length, a/W, on absorbed energy, it is possible to estimate the dynamic fracture toughness from the measured energy. It can be found that the estimate values of dynamic fracture toughness are in good agreement with those calculated by another method.
