A study on the role of adhesives in weld-bonded joints

Using a three-dimensional finite element analysis (FEA) method, the effect of elastic modulus and thickness of adhesives on the stress distribution in weld-bonded joints was studied to address the role of adhesive layer. Norm al stress and shear stress distributed at the edges of a spot weld and in t he lap region were computed for weld-bonded joints made with adhesives of d ifferent elastic moduli or thicknesses. The results showed great stress con centration at the edge of the spot weld in weld-bonded joints when the adhe sive layer was thick or had a low elastic modulus. Shear stress values in a dhesive layers were low under the same circumstances. Stress concentration around the spot weld was reduced and the shear stress in the adhesive layer was increased by increasing the elastic modulus or decreasing the thicknes s of the adhesive layer. An adhesive layer with appropriate thickness and e lastic modulus is necessary to obtain reasonable distribution of stresses i n the whole lap region of a weld-bonded joint. A thin adhesive layer of hig h elastic modulus is favorable to the fatigue properties of weld-bonded joi nts, and it is recommended on certain conditions.