Local reinforcement of adhesively bonded square shape aluminum energy absorber with CFRP under quasi-static axial loading: An experimental and numerical study

This study presents experimental and numerical investigations on the effects of composite ply angle, thickness and number of layers on energy absorption behavior of adhesively bonded carbon fiber-reinforced plastic/aluminum hybrid structure under quasi-static axial loading. This paper aims to use the advantages of adhesive bonding for the local strengthening of a square shaped aluminum energy absorber by composite and as a result achieving desirable energy absorption behavior prior to failure in the connection and without heterogeneous deformation of the structure while reducing the weight of the structure and usage of material and at the same time obtaining favorable results compared to the traditional ways like reinforcing the aluminum structure with composite globally. For this purpose, two models were made and analyzed; one reinforced with four L-shaped composites adhesively bonded using Araldite 2015 to four outside corners of the aluminum square and the other reinforced locally to four corners from within the square. Finite element model was developed for analysis of these hybrid structures. Five different ply angles for composite and multiple number of composite layers varied from 2 to 8 layers under the same and different thicknesses were investigated. Moreover an alpha factor has been determined to measure the importance of local reinforement of the square shape aluminum energy absorber by L-shaped composites. The results showed that compared to aluminum and aluminum with global composite reinforcement energy absorbers, due to the adhesive connection between aluminum and composite in the locally reinforced CFRP/aluminum specimen, the composite had better energy absorption by following the collapse pattern of aluminum and creating a continuous collapse and failure modes. The results indicated good coordination and agreement between the simulated models and the experimental tests. The findings from this experiment demonstrates significant potential for local reinforcement of structures employing adhesives. Utilizing such connections and the ability to strengthen specific areas based on arbitrary geometry and strengthening location could offer substantial opportunities in constructing lightweight structures with high energy absorption across diverse applications.