A stress analysis of a thermally loaded bimaterial interface: A localized hybrid analysis

A complex state of stress at a bimaterial interface in a steel/brass plate subjected to a uniform thermal load is investigated using a localized hybrid method which combines an experimental method (high-sensitivity moire interferometry) and a numerical method (finite element analysis). A preliminary discussion of the mechanics of the problem is presented in terms of theoretical and finite element numerical solutions. It is shown that a three-dimensional stress system is generated at this thermally loaded bimaterial interface in the vicinity of the free surface. High-gradient and high-value surface stresses normal to the interface have opposite signs in each material and, very close to the interface, change sign, at least in one of the materials, to satisfy the equilibrium at the interface. The published moire experimental results of this problem are evaluated and further interpreted from the mechanics point of view by means of a localized hybrid analysis. In such an analysis, several comprehensive stress fields are obtained, the free-surface effect regions are identified, and the extent of these regions is determined in association with numerical solutions. The apparent equilibrium paradox suggested in the moire experiment is resolved by a comparison of the localized hybrid and numerical solutions in terms of the mechanics. The three-dimensional nature of this problem is documented. The largest surface stress normal to the interface, which may initiate failure, is found at the corner which is located in a region of intersection of two free-surface effect zones.