Shape optimisation of adhesive fillets

The evolutionary structural optimisation method (EVOLVE) was employed to optimise the shape of adhesive fillets found in tabs of tensile test specimens in which the adherends were titanium and T800 unidirectional tape bonded with a generic paste adhesive. Typically, the selection of an adequate joint requires a number of design and analysis cycles which rely heavily on the trial-and-error method. The EVOLVE method relies for the cases presented, on an iterative finite element analysis and progressive removal of elements which takes the guess work out of the design loop. The objectives in both cases are to minimise the maximum stresses in the joints. The EVOLVE code was found to be effective in reducing the maximum principal stress in the adhesive for all models studied. The reduction in maximum principal stress achieved with respect to the baseline model (CFRP upper and middle adherends with Eadhesive=3.8 GPa) ranged between 48 and 64%. The peak peel stresses in the central CFRP adherend and in the adhesive were reduced by up to 66%.