New developments for in situ ultrasonic measurement of transient temperature distributions at the tip of a copper resistance spot weld electrode

This paper presents the new development of a joint thermal simulation and ultrasonic time of flight (TOF) measurement technique for the In situ measurement of transient temperature distributions. A coupled finite element model, using conductive media DC and heat transfer by conduction, was used to simulate the expected transient temperature distributions within the copper electrode during welding. Simulated temperature distributions were then used to model acoustic wave propagation through the geometry. This paper shows how the inverse problem solution of determining the actual temperature distribution and electrode tip temperature can be performed by using measured dynamic time of flight data in conjunction with finite element results of expected wave propagation.