Quantification of Interface Adhesion Strength of Adhesive Bonded Dissimilar Materials Using Ultrasonic Technique

Abstract

Ultra-Sonic testing technique is considered a powerful tool for non-destructively assess and analyse the interface between two adhesively bonded materials. The ultrasonic waves reflect after interacting with the adhesively bonded interface. This reflection can be evaluated in order to estimate the shear strength of the adhesively bonded imperfect bond between two dissimilar materials. A correlational analysis is employed using relationship of sound waves to shearing and Regression Analysis to assess the reflected signal from the interface of two dissimilar adhesively bonded materials. In this investigation to quantify the relationship between interface adhesion strength and ultrasonic-technique, two adhesively bonded dissimilar materials were used. A block of 4340 Steel adhesively bonded with Poly-Urethane to a silica winded Composite was evaluated in this study. The reflection signal from the bonded material was analysed and compared with the reference signal acquired from the unbonded part using UT-method to obtain the Interfacial Stiffness (Kn), Reflection Co-efficient (RL) and Return Loss (R). These three variables were then evaluated and correlated with the Shear Strength of the bonded part measured by tensile testing. Analysis of results acquired from the experiments shows that the shear-strength is cumulative linearly with the rise in Gain and Reflection Coefficient with a correlation of 98%. It validates that the shear strength can be characterized and calculated using the reflection coefficient. Moreover, the mathematical model developed discloses the feasibility that shear strength can be evaluated of two dissimilar adhesively bonded materials using non-destructive methods.