The effect of stitching on mode I and mode II strain energy release rates for debond configurations is studied using an analysis based on plate finite elements and the virtual crack closure technique. The stitches were modeled as discrete nonlinear fastener elements with a compliance determined by experiment. The axial and shear behavior of the stitches was considered with both the compliances ...

Ultrasonic methods have been implemented for in situ sizing of fatigue cracks near fastener holes. These techniques, however, only provide an estimate at the time of the measurement and cannot predict the remaining life of the structure. In contrast, statistical crack propagation approaches model the expected fatigue life based on worst-case fatigue process assumptions. The authors have recentl...

We investigate the origin of undesirable transverse cracks often observed in thin films obtained by the layer transfer technique. During this process, two crystals bonded to each other containing a weak plan produced by ion implantation are heated to let a thin layer of one of the material on the other. The level of stress imposed on the film during the heating phase due to the mismatch of ther...

A stiff thin film on a heated compliant substrate may buckle when the system is cooled due to the thermal expansion mismatch between the film and substrate. Highly ordered and disordered herringbone patterns wavy structures then emerge as the system continues to cool. We have established an analytic approach to study one-dimensional, checkerboard, and ordered herringbone buckling patterns. The ...

T he success of electronic paper, roll-up displays and many other potential applications of flexible electronics will depend on the availability of electronic materials that can be stretched, compressed and bent. Previous efforts to develop electronic materials that can be mechanically deformed without breaking have mainly focused on small organic molecules and polymers. Unfortunately, these ma...

Till now, various models have been proposed in literature to simulate the behavior of riveted structures. In order to find the most accurate analytical method in modeling the dynamic behavior of riveted structures, a comparison study is performed on several of these models, in this research. For this purpose, experimental modal analysis tests are conducted on a riveted plate to verify the effic...