Modulus grading versus geometrical grading of composite adherends in single-lap bonded joints

The behavior of single-lap adhesive bonded joints with modulus and geometrically graded adherends was examined. The modulus grading of the adherend was provided by continuously varying the braid angle and geometrical grading provided by varying the adherend thickness in the overlap region. The peak stress distribution and transverse deformation at the adhesive mid-thickness calculated using finite element method was used to compare the performance of modulus grading and geometrical grading. It was noticed that for certain cases, modulus grading provides reduced stress levels compared to geometrical grading. In certain other cases they demonstrate benefits similar to geometrically graded adherends. In case of shear stress reduction, modulus grading provided better performance; however, it is possible to combine modulus and geometrical grading to evolve an overall better performing single-lap bonded joints.