Thermography in manufacturing: nondestructive evaluation of ultrasonic spot welds of automotive battery pack

Abstract

Flash thermography-based nondestructive evaluation (NDE) procedure for inspection of spot welds of automotive battery packs has been developed. A mathematical model of heat propagation has been proposed. The underlying equations have been solved analytically for simple geometry and numerically, using ANSYS FEA package, for the case of general geometry. Based on the proposed model, the size of the fused area of spot welds was determined from thermographic experiments and a correlation with direct measurements was obtained.In a separate set of experiments, the response to a typical flash impulse was determined and the characteristics of the heat pulse were determined by using least square approximation. The reconstructed shape of the flash impulse was used for NDE of welds between thin sheets.

Automatic Inspection of Spot Welds by Thermography

“…[4], and specifically for spot welds, see e.g. [5][6][7][8]. The interest for this method has increased during the last years, since it is a full-field method suitable for automatic inspection.…”

“…All experiments were conducted with a transmission set-up, double sided. Both Schlichting et al [7] and Shpartko et al [8] used a flash lamp for heating a spot weld area and determined the spot weld position and size in a transmission setup. Lee et al [6] used lock-in thermography to measure the nugget size of a spot weld.…”

In situ velocity measurements of very high power ultrasonic additive manufacturing using a photonic Doppler velocimeter

“…Other non-traditional NDE techniques such as shearography and thermography can also be used to evaluate bond quality. 10,11 In both cases thermal energy is introduced to the part and the resulting 1 thermal or mechanical response can be linked to bond quality. But again, these processes are ex situ and need to be performed post consolidation.…”