Predicted thermal stresses in a bimaterial assembly adhesively bonded at the ends

Abstract

The interfacial shearing and "peeling" stresses in an elongated bimaterial assembly, adhesively bonded at the ends and subjected to the change in temperature, are predicted, based on an approximate structural analysis (strength-of-materials) model. The stresses in the bonded joints due to the thermal expansion (contraction) mismatch of the adherend materials within the bonded areas ("local" mismatch), as well as the stresses, caused by the thermal mismatch of the adherend materials within the unbonded midportion of the assembly ("global" mismatch), are considered. The interaction of the "local" and the "global" stresses is evaluated and analyzed. It is shown that if the bonded joints are made long enough, the maximum stresses in the assembly will not be different from the stresses in an assembly with a continuous adhesive layer, no matter how long the unbonded midportion of the assembly might be. The obtained results can be helpful in the stress-strain evaluations and physical (mechanical) design of bimaterial assemblies in electronic and photonic packaging. © 2001 American Institute of Physics.