Impact Tensile Fracture Energy of Glassfiber Reinforced Plastic

Abstract

Several simple and accurate methods of measuring the impact tensile fracture energy of fiber reinforced composites were examined by using a drop-weight type impact tensile testing machine. The tensile fracture energy was found to be expressible by a normal distribution function and, therefore, the Up-and-down method was suitable for measuring it. The results by this method were compared with those obtained by using the Probit analysis and the Impulse method. In the Impulse method, the fracture energy was calculated from the impulse, or the change of the momentum of the weight. The Up-and-down method was found to be a simplest and most effective method because it requires neither a large-size sample nor an additional device for measuring the velocity of a weight or the displacement of a specimen.
The impact tensile fracture energy of glass cloth reinforced polyester resin laminates was remarkably large in comparison with the static tensile fracture energy. It was found that a material which shows large energy absorption in the Charpy impact test did not always show a good performance in the impact tensile test. This result suggests that the energy absorbed in the impact tensile test should be considered as an important property of fibrous composites like Charpy impact strength.