In this paper, closed-form solutions for the adhesive stresses in bonded composite
single-strap butt joints have been obtained. Two strategies were used for deriving the
adhesive peel stress. The solutions are applicable to a butt joint made from
different adherend and doubler laminates, as well as the unbalanced single-lap
joints. In addition, three-dimensional finite element models of the unit-width
composite joints were created for analyzing the adhesive stresses under a plane
strain condition. A total of six joint conditions, three joint configurations
and each with two layup sequences, were studied. Consistency in the peel
stress predictions was obtained from the two theoretical strategies. Good
agreement has been achieved between the theoretical and finite element
results. The effects of the doubler thickness and laminate layup sequence
on the adhesive stress variation can be displayed. The theoretical solution
would provide a solid foundation for supporting the practical composite joint
assessment.
