The effect of residual thermal stresses on the viscoelastic behavior of adhesively bonded joints

Present stress analysis of adhesively bonded joints suffers from inadequate adhesive material characterization. The lack of correlation between bulk adhesive properties and the corresponding in-situ behavior has led to numerous adhesive test geometries. The current study was an attempt to predict the nonlinear viscoelastic response of an adhesive in-situ using properties obtained from a pure shear test geometry. Four candidate adhesive test geometries were studied both analytically and experimentally in terms of accurate shear property determination and realistic adhesive bond simulation. The thick adherend joint was chosen as the experimental reference of actual viscoelastic response in-situ; the Arcan specimen provided a pure shear stress state for material viscoelastic characterization. Results of finite element analysis and extensive experimental evidence suggest that residual thermal stresses alter the in-situ adhesive properties compared to the bulk adhesive: Furthermore, preliminary results indicate that the free volume nonlinear viscoelastic theory accounts for the effect of residual strains on the in-situ adhesive mechanical response.