Piezocapacitive Sensing for Structural Health Monitoring in Adhesive Joints

Adhesive joints are becoming increasingly important in engineering, especially in the field of mobility applications such as automotive and aircraft. As done in recent applications, loading the adhesive with carbon nanoparticles can increase the mechanical strength of the joints. Additionally, adhesives containing carbon nanoparticles also exhibit a piezoresisitive and piezocapacitive effect, i.e. the electrical resistance and the electrical capacitance change when mechanical stress is applied to the joint. In this paper we focus on the piezocapacitive effect and present experimental results for a setup using single lap joint specimen comprising two aluminum plates overlappingly connected using conductively loaded adhesive. It is shown that the system can detect forces as low as 0.4 N.