Numerical and Experimental Investigation of Joining Aluminium and Carbon Fiber Reinforced Composites by Electromagnetic Forming Process

Abstract

Carbon fiber reinforced composites became so popular in automotive, aerospace, marine and military industries in past years, because of their high strength, low weight and subsequently high specific strength. The basic challenges of producing the CFRP components are their forming and joining techniques. In this study, a finite element analysis is carried out by the purpose that the optimum geometries to be selected for manufacturing an electromagnetically assisted joining by forming system of two aluminium and CFRP sheets. Electromagnetic forming is one of the high speed forming technologies that uses the Lorentz force as a forming pressure. High speed and usually one-step forming process are some of its advantages while, the necessity of high electrical conductivity of the work-piece is an important restriction. Aluminium deformed in this study, so that its behaviour is assumed to be dependent on the strain rate. Also, the hardening behaviour of aluminium is described by the Johnson-Cook material model. The joining by forming system is modelled in the finite element code by means of the ABAQUS 6.13 FEM software. The magnetic pressure pulse of the coil is described by the VDLOAD subroutine to apply it to the lower surface of the aluminium field shaper. Under influence of this force, the punch bulges the aluminium sheet into the hole on the CFRP sheet and a cavity on die helps the bulged region to form a mechanical interlock. In the experimental investigations, predrilled CFRP sheets with different diameter holes and locations are used. The effect of geometrical parameters such as metal thickness are studied on the quality of joints. The most important parameter to be considered here, is the tensile strength of the joints. Therefore, the joint samples had been applied under tensile test in order to consider failure modes, experimentally.