3-D non-linear stress analysis on the adhesively bonded composite joint under bending moment

• This model describes the mechanical behaviors of Single Lap Composite Joints.
• The normal and shear stress distributions are extremely sensitive to three-dimensional effects.
• The fiber orientation and ply stacking sequence have a significant effect on the stress distribution.
• The 3-D finite element method is essential to evaluate explicitly the stress and failure states.

This paper presents an approach to predict the three-dimensional effects (anti-clastic, free edge and bending–twisting coupling effects) and to assess the effects of the fiber orientation angle of the laminates on the stress distributions and the failure prediction in the Single Lap Composite Joints (SLJs) subjected to a bending moment via a 3-D non-linear finite element method. In the analysis, the composite adherends (AS4/3501-6) with five different fiber orientation angles ([90/±45/0]2s, [0/90]4s, [45/−45]4s, [0]16 and [90]16) were assumed to behave as linearly elastic materials while the adhesive layer (FM 73) was assumed to be nonlinear. Also, the nonlinear geometric deformations of the SLJs were also taken into account. Consequently, it is seen that the state of stress in the vicinity of the free edge of the joint is fully three dimensional which has not been taken into account in any classical theory so far and the normal and shear stress distributions are extremely sensitive to this three-dimensional effects. From this aspect, the three-dimensional finite element analysis is a necessity for understanding explicitly the stress and failure states. Also, for both the adherends and the adhesive layer, the ply stacking sequence has a significant effect on the stress distribution and the failure.