Strength Improvement of Composite-Steel Lap Joint by Reverse Step and Grading the Overlap with Fiber

The failure of adhesive joints is generally influenced by the non-uniform distribution of stresses with the maximum value, located near the ends of the overlaps. In this study, using a new method, The effect of reverse steps on joint strength has been investigated. Also, carbon fiber is used as a reinforcing element in the adhesive layer and the properties on each step are graded symmetrically by carbon and glass along the overlap. The use of carbon at the joint surface, the grading of the joint area with fiber and the mechanical interference through reverse steps, have positive effects on joint strength. By grading the overlap by carbon and glass, the distribution of shear and peel stress have become more uniform and the load of the failure, increased by 41.7%. But the greatest increase is achieved using two reverse steps and graded adhesive layer with carbon and glass on each step, by a significant amount of 188.5%.

Keywords:

Functionally graded joint , Co-curing method , Mechanical interference , Reverse step