Variable modulus adhesives: an approach to optimised joint performance

This paper describes a practical method for joint optimisation using a variable modulus bondline. Linear finite element models have been developed to optimise the bondline properties and to help understand how variable modulus bondlines distribute stresses and strains. Initial experimental results have shown significant changes in the mode of failure and increases in joint strength of lap joints compared to a single-modulus adhesive that is typically used to bond unidirectional carbon fibre reinforced plastic (CFRP). Joint performance has also been improved in steel to CFRP joints where yielding of the steel occurs.