Boron nitride inclusions within adhesive joints: Optimization of mechanical strength and bonded defects detection

Abstract Non Destructive Testing (NDT) by active InfraRed Thermography (IRT) of bonded Carbon Fibers Reinforced Plastic (CFRP) laminates is a very challenging issue. Adding Boron Nitride (BN) particles within the joint material provides an interesting solution to better capture bonding defects. Though increasing additives leads to the improvement of NDT, the validation of this solution requires the mechanical characterization of the new joint material. In this way, the influence of particles on the mechanical properties of the adhesive joint is first investigated via double strap lap shear tests for different BN volume fraction. At the same time, controlled size void inclusions are generated within composite assemblies in order to evaluate the IRT ability to detect bonded defects inside BN-based adhesives. It is demonstrated that thermal data post-processing methods such as Singular Values Decomposition (SVD) and Principal Component Thermography (PCT) help to get the best trade-off between mechanical performance and defect detection.