The Design of In-Plane Shear and Tension-Loaded Bonded Composite Lap Joints

The stress analysis of a bonded joint carrying combined in-plane shear and tension load is presented. A general equation is derived that governs the transfer of shear load through a joint. For the case of uniform in-plane shear loading, a closed-form solution exists that is directly analogous to the well-known tension-loaded case. When shear and tension loads are simultaneously applied to a joint, the results of stress analyses treating each loading case separately are superimposed to calculate a combined biaxial shear stress state in the adhesive. Predicting the elastic limit of the adhesive for a lap joint under combined loading is then accomplished by using the von Mises yield criterion. This approach allows the calculation of a limit load envelope that maps the range of combined loading conditions within which the joint is expected to behave elastically. An example design case study of a bonded I-beam shear web is included.