Determination of thermal strains in the neighborhood of a bimaterial interface

Abstract

An experimental analysis was conducted on a bimaterial plate of steel and brass, subjected to a uniform temperature change. The steel and brass portions of the plate were joined along a common edge with a nearly zero thickness medium. Whole-field, in-plane displacement measurements U and V were made by means of high-sensitivity moiré interferometry. The corresponding distributions of stresses, σ_x, σ_y, and τ_xy were determined for the free surface. Near the interface, and along its length, the largest stresses were σ_y, acting perpendicular to the interface. The σ_y peaks occurred very close to the interface, but not on it. These peak values were tensile in the steel and compressive in the brass. The transition between these opposite peak stresses featured an extremely strong gradient in a 50 µm interface zone. The distribution was akin to that of a stress singularity, but the stresses reached finite peak values in the physical experiment. Even larger stresses were found near the corner, where the interface of the two materials intersects the free edge. Both macroscopic and microscopic moiré interferometry were required to determine the stress distribution.