A Greatly Improved A4Ei Code for the Analysis of Bonded Composite Joints
Stress analyses of bonded joints have ranged from using simplified average shear stresses in adhesive to using extremely detail finite element modeling of adhesive joints. A compromise between these two extremes is a 1-dimensional approach advanced by Hart-Smith which has been developed into a computer code designated A4EI. This code has found widespread applications in the design of many bonded composite joints throughout the aerospace industry. However, a serious drawback of this code is its convergence problems especially for multi-stepped bonded joints. This is because the A4EI code employs an iterative scheme to solve a system of partial differential equations which is harder and harder to converge when the number of steps becomes large.In this paper the same bonded joint problems considered by A4EI are formulated with a different solution procedure that allows for rigorously derived closed-form solutions which completely eliminated the non-convergence issue of A4EI. In addition, this new formulation is based on a more general bonded joint model and with more general loading conditions so that all current A4EI functionalities can be deduced from this new method as special cases. Comparisons with A4EI and other existing solutions are shown to demonstrate the capability of the new code.
Author: Edward Wung
Conference: SAMPE Seattle 2017