Simplified Procedures for Designing Adhesively Bonded Composite Joints

Procedures for the preliminary design of composite adhesive joints are described. Typical joints, their respective free body diagrams and approximate equations for estimating the stresses in each of these typical joints are summarized. Equations are also presented to check the critical conditions of the joint, such as: minimum length, max imum adhesive shear stress and peel-off stress. To illustrate the procedure, sample designs are described in step-by-step fashion for a butt joint with single doubler subjected to static loads, cyclic loads and environmental effects. The results show that (1) unsymmetric adhe sive joints are inefficient and should be avoided, and (2) hygrothermal environments and cyclic loads dramatically reduce the structural integrity of the joint and require several joint lengths compared to those for static load with no environmental effects.