We propose a strength analysis method for three-dimensionally fiber-reinforced composite materials. The analysis is based on a stress averaging method for the individual mechanical properties of fiber and matrix assuming a homogeneous orthotropic solid for the 3D composite. Using the fundamental formula for Young's modulus derived by the stress averaging method, the strength analysis procedures are discussed. The tensile stress analysis is executed for a five-axis woven carbon/epoxy 3-D composite, and their results are compared to the experimental data. The analytical results show comparatively good agreement with the experimental results.
The acoustic emission (AE) technique was applied to investigate the fracture processes of a fiber-reinforced glass. Pyrex glass reinforced with silicon carbide fibers coated 140 nm thick carbon was used as the test material. The matrix cracking behavior was observed using a replication technique. The fiber breaking process was analyzed using a probabilistic fracture model in which the fiber strength distribution was considered. By comparing the AE behavior during the tensile test with the fracture process evaluation mentioned above, the AE technique proved to be effective for investigating the fracture process of the material system studied. AE signals with high amplitude corresponded to fiber breaking ; AE signals with low amplitude corresponded to matrix cracking and interfacial debonding.
Using glass fiber reinforced epoxy composite (GFRP), the abrasive wear properties to the abrasive papers have been examined with some different fiber orientations of θ. It was cleared that the abrasive wear rate increased linearly with increasing θ, and this tendency was the more remarkable to the rougher abrasive papers.