Three-dimensional finite element analysis of double-lap composite adhesive bonded joint using submodeling approach

Three-dimensional stress analysis is performed for double-lap composite-to-composite adhesive bonded joint exposed to uniaxial extension. The submodeling approach using 27-node solid element available in the recent versions of ABAQUS is utilized. Principal objectives are: to explore computational advantages provided by the multi-step submodeling approach and perform a comprehensive numerical study of three-dimensional (3D) stress variations in the joint structure, considering adhesive layers as 3D elastic entities. Numerical results obtained from the "global" analysis show fast displacement convergence everywhere in the joint, but do not clearly indicate if the stresses converge in the regions near the ends of the overlap. Besides the fact that a huge number of elements is required for the stress convergence study in the aforementioned regions, a serious computational obstacle have been also experienced: the element aspect ratio gets so high that the "zero or negative element volume error" is indicated, and results become unreliable. In order to overcome these problems, a multi-step submodeling approach is further explored. Its application has allowed to convincingly demonstrate that some stress components are not converging along certain lines belonging to the ends of the overlap. Additional numerical study performed with a two-dimensional plane stress formulation has shown that when taking into account a spew fillet, stress distributions near the end of the overlap change radically. It is concluded that submodeling approach provides an efficient computational tool for enhancing stress analysis in the sites of high stress gradients. (C) 1999 Elsevier Science Ltd. All rights reserved.