Aluminum beam reinforced by externally bonded composite materials

A recently popular method for retrofitting reinforced structure beams is to bond composite plates to their tensile faces. An important failure mode of such plated beams is the debonding of the composite plates from the base material of the beam due to high level of stress concentration in the adhesive at the ends of the composite plate. This paper, shows and presents in more detail a closed-form rigorous solution for interfacial stress in cantilever aluminum beams strengthened with bonded composite (sika wrap) plates and subjected to a uniformly distributed load. The results show that there exists a high concentration of both shear and normal stress at the ends of the laminate, which might result in premature failure of the strengthening scheme at these locations. A parametric study has been conducted to investigate the sensitivity of interface behavior to parameters such as laminate and adhesive stiffness, the thickness of the laminate; the effect on plate length of the strengthened cantilever beam region, the effect of adhesive (modules, thickness) and the effect of loading and geometry for the cantilever beam; where all were found to have a marked effect on the magnitude of maximum shear and normal stress in the composite member. The theoretical predictions are compared with other existing solutions. Finally, this research is helpful for the understanding on mechanical behaviour of the interface and design of the composite-aluminum hybrid structures.