ON THE COMBINED MODE-I MODE-II FRACTURE-TOUGHNESS OF A FIBER-REINFORCED POLYMER COMPOSITE

The nature of failure processes in composites is governed by the prope rties of the matrix, reinforcement and the interface. The complex natu re of these materials makes the relationship between microstructure an d fracture properties less direct than in monolithic materials. This n ecessitates the need for the testing of these composites under a varie ty of stress states and then correlating the failure path to the local microstructure and/or stress state. This paper will address issues in volved in determining the tensile and shear susceptibilities of a fibe r reinforced polymer composite. The use and application of a modified double edge notch specimen is discussed. The paper also discusses the relationship of the results obtained for this material with the concep t of a fracture mechanism map which has been proposed to relate the sh ear susceptibility of materials to their overall fracture toughness an d well as the local micromechanisms involved.