Thermal residual stresses in an adhesively bonded functionally graded tubular single lap joint

Abstract

Elastic thermal residual stress analysis of an adhesively bonded functionally graded tubular joint was carried out for a uniform temperature drop using an isoparametric axisymmetric layered finite element. The hoop stress σ θθ , axial stress σ zz and transverse shear stress σ rz were dominant for both free and constrained models of the tubular joint. The stress concentrations occurred around the adhesive free ends, especially at the left and right free edges of the inner tube–adhesive interface and at the left free edge of the outer tube–adhesive interface. Increasing layer number played important role on the peak stress values in the ceramic layer of the metal-rich composition and in the metal layer of ceramic-rich composition since a sudden transition between two phases in these layers, whereas its effect on the through-the-thickness stress profiles was minor. In addition, the through-the-thickness stress profiles at the critical locations in both tubes and in the adhesive layer were affected evidently by the directional material composition variation. The compositional gradient had a minor effect on the through-the-thickness stress profiles whereas only the peak stress values were affected. The hoop, axial and shear stresses increased with increasing compositional gradient. In the free joint model, the effects of the compositional gradient, layer number and the directional compositional variation on the through-the-thickness stress variations were apparent whereas the effect of the boundary condition became noticeable in the constrained joint model.