Adhesive Layer: Predicted Thermal Stresses in the Adhesive

ABSTRACT: We consider a thermoelastic problem for an adhesively bonded assembly with identical nondeformable adherends and nonhomogeneous adhesive layer: its midpor-tion has a larger coefficient ofthermal expansion (contraction), larger Young's modulus and smaller Poisson's ratio than the peripheral portions. An elongated assembly is examined, and the case when the assembly is manufactured at an elevated temperature and is subse-quently cooled down to a low temperature is addressed. The objective ofthe analysis was to develop a simple stress model for the evaluation ofthe thermally induced stresses and displacements in the adhesive layer. These arise because of the thermal contraction mismatch of the adhesive material with the material of the adher-ends, as well as because of the mismatch of the material in the midportion of the adhesive layer with the material in the peripheral portions. We conclude that sufficiently long periph-eral portions can reduce substantially the stresses and the distortions ofthe cross-sections in the mid-portion ofthe adhesive layer, thereby resulting in a situation when an appreciable in-nerregion ofthe midportion has a uniform state ofstress and strain, and next-to-zero longitu-dinal displacements. The obtained results can be helpful in the analysis and design of adhesively bonded assemblies of the type in question