We describe a non-destructive and inexpensive way of measuring the interface toughness between polymeric layers in microfabricated devices. A flat surface is bonded under pressure to a surface patterned with microscopic steps. When the pressure is removed, cracks develop at the interface as the material peels away from the steps. The toughness of the bond can be inferred from the crack lengths....

A new class of systems of strongly singular integrodifferential equations is examined, which emerges in the study of the bridged interface crack growth, e.g., in fiber stitched layered composites. This work generalizes the asymptotic analysis of strongly singular integral equations by Willis and Nemat-Nasser [Quart. Appl. Math., 48 (1990), pp. 741–753]. Singular perturbation solutions up to the...

The bonding strength between dissimilar materials in composites is often relatively weak. Interface debonding and cracking are of common occurrence. As an e€ ective method to minimize such failures, ® bre stitching is used to enhance the bonding strength when joining layers in polymer composites. With the presence of the reinforcing ® bre, the overall elastic response for each component of the ...

The formulation for thermal stress and electric displacement in an in®nite thermopiezoelectric plate with an interface and multiple cracks is presented. Using Green's function approach and the principle of superposition, a system of singular integral equations for the unknown temperature discontinuity de®ned on each crack face is developed and solved numerically. The formulation can then be use...

The present paper deals with the mixed mode fracture analysis of a weakened orthotropic half-plane with multiple cracks propagation. The orthotropic half-plane contains Volterra type glide and climb edge dislocations. It is assumed that the medium is under in-plane loading conditions. The distributed dislocation technique is used to obtain integral equations for the dynamic problem of multiple ...

Cracks appeared in GaN epitaxial layers which were grown by a novel method combining metal organic vapor-phase epitaxy (MOCVD) and hydride vapor-phase epitaxy (HVPE) in one chamber. The origin of cracks in a 22-μm thick GaN film was fully investigated by high-resolution X-ray diffraction (XRD), micro-Raman spectra, and scanning electron microscopy (SEM). Many cracks under the surface were first...