| This dissertation develops methods for evaluating the tribological behavior of anisotropic materials. The underlying objectives of the work are: (1) to elucidate the relationship between the sliding frictional contact and the fiber orientations of FRP composites; (2) to explore the relationship between the anisotropic strength and the wear of FRP composites and develop an innovative wear model of FRP composites; and (3) to derive a general approximate solution for analyzing the contact behavior of transversely isotropic coatings such solid lubricant films.; The first goal was achieved in two steps. First, by incorporating anisotropic contact theory, the elastic properties of FRP composites, and the analytical expressions of Bamett-Lothe tensors, the contact behavior of FRP composites in the three principal fiber orientations (transverse, normal, parallel) was deduced. Specially, the influence of fibers, matrices, volume fractions, and friction coefficients on the contact behavior was matrices, volume fractions, and friction coefficients on the contact behavior was ascertained. Next, through the numerical solution of the explicit expressions of Barnett-Lothe tensors, the relationship between the contact performance and the arbitrary fiber orientations was examined. Based on this approach, the influence of fiber orientations on the contact pressure and the contact patch was determined.; To develop an anisotropic wear model of FRP composites, the Tsai-Wu failure strength criterion was employed to establish the relationship between the wear and the contact stress. The theoretically predicated results were in good agreement with the previously published experimental data. This correlation demonstrates that the anisotropic failure strength criteria may be used to explain the anisotropy of wear in FRP composites.; Finally, a set of approximate solutions for thin, transversely isotropic coatings was derived to gain deep insight into the coated structures. These easy-to-use solutions are helpful for optimizing the contact behavior of thin coatings used in the design of contacting components. |
