Study of adhesive bonds using low‐frequency obliquely incident ultrasonic waves

The effect of the difference between slip and rigid boundary conditions on the value of the ultrasonic wave reflection coefficient from an interface is used to study properties of adhesively bonded interfaces. It is shown that changes of the amplitude of the reflected ultrasonic wave during adhesive curing occurred simultaneously with changes of the ultrasonic velocity in the adhesive. The method can be used for cure monitoring of thin adhesive layers and predicting the joint strength. The sensitivity of the method to evaluate interface properties is shown to be higher for thinner adhesive interface films.