Dimensionless parameters in symmetric double lap joints: An orthotropic solution for thermomechanical loading

Two thermomechanical analytical models are developed for orthotropic double lap joints with a view to identifying key dimensionless parameters that describe the behavior of the joint under combined thermal–mechanical loads. The solutions, based on the principle of virtual work, differ in the complexity of the assumed stress field. The first solution is similar to Volkersen [Volkersen, O., 1938. Die niektraftverteilung in zugbeanspruchten mit konstanten laschenquerschritten. Luftfahrtforschung 15, 41–47] with the addition of orthotropic and thermal effects. The second solution, extending the work of Davies [Davies, G.A.O., 1982. Virtual Work in Structural Analysis, John Wiley & Sons, New York] captures the peel stress as well as the traction free boundary condition at the adhesive edge. Relevant non-dimensional parameters are identified in terms of geometric, material, and load quantities. A dimensionless load ratio is identified which dictates the shape of the stress distribution. This ratio can also be used to quickly determine the dominant loading mechanism. Dimensionless stress plots are presented for representative lap joints.