| Various contact and crack problems for the orthotropic half-plane, stiffened by orthotropic films, are considered here. Two film models are presented i.e. the membrane model where the effect of bending stiffness of the film is neglected and the plate model where this effect is included. Based on these models, the dissertation is divided into two parts.; In the first part, with the membrane model, the film/half-plane contact problem is formulated in terms of a singular integral equation with an unknown contact shear stress. This stress is determined from a solution of the integral equation and film edge stress intensity factors are determined. Then, the internal and edge crack problems for the half-plane are solved to determine the crack-tip stress intensity factors. Internal and edge crack problems, for the case where a single film is bonded to the half-plane, are also formulated in terms of a system of singular integral equations. This system of equations is solved to determine stress intensity factors at the singular points. Finally, the edge crack problem for symmetric films on the half-plane surface, is solved. For the edge crack cases, asymptotic analyses are carried out to determine the nature of the singularities at all locations of geometric and stress discontinuity.; In the second part, for the film contact problem, it is demonstrated that the stress singularity is complex and normal and shear contact stresses are coupled. The problem is represented in terms as a pair of singular integral equations of the second kind with the stresses as unknown quantities. These stresses are determined along with the complex, film edge stress intensity factor. Next, internal and edge crack problems for the case of a single film on a substrate are solved. Finally, the edge crack problem for symmetric films is solved.; Insights into the characterization of materials in plane orthotropic elasticity are presented. Results from the orthotropic formulations for the special case of isotropy are shown to compare well with the isotropic results obtained in this dissertation and in the literature. |
