Nondestructive Testing of Ultrasonic Welded Polymer-Based Composites Using Active Thermography Method

Abstract

Ultrasonic welding is one of the most common methods for joining the polymer parts. It provides a rapid joining with a proper strength. Ultrasonic welding is also considered as a clean joining. This method is widely used in joining of thermoplastic parts. But, in order to weld the thermoset parts, a coupling layer shall be incorporated. This method occasionally is perfect because of voids and improper adhesion between to welded parts, leading to significant weld strength reduction. Consequently, application of a kind of NDT method could be useful for quality assurance of these parts. In this paper, active IR thermography is employed to nondestructively test of ultrasonically welded Glass Fiber Reinforced Plastics (GFRP). In order to study the weld microstructure, SEM analysis is performed. The results indicated that the IR thermography is capable to detect the existence of some defects in the welding zone. The Lap-shear tests indicate that the dimensions of the defect reduce the weld strength, significantly.