Correlating Variations in the Dynamic Resistance Signature to Weld Strength in Resistance Spot Welding Using Principal Component Analysis

Abstract

Traditional quality control of resistance spot welds by analysis of the dynamic resistance signature (DRS) relies on manual feature selection to reduce the dimensionality prior to analysis. Manually selected features of the DRS may contain information that is not directly correlated to strength, reducing the accuracy of any classification performed. In this paper, correlations between the DRS and weld strength are automatically detected by calculating correlation coefficients between weld strength and principal components of the DRS. The key features of the DRS that correlate to weld strength are identified in a systematic manner. Systematically identifying relevant features of the DRS is useful as the correlations between weld strength and DRS may vary with process parameters.

Functional clustering methods for resistance spot welding process data in the automotive industry

“…Consistently with the technological literature, 8,32 being the minimum point abscissa practically constant and the maximum point the landmark for the start of nugget formation (see also Section 2), we can state that the smaller the phase difference, and thus the larger the time interval between the local maximum and the end of the welding process, the more the heat energy supplied for nugget growth. Note that the inflection point typically located between the local minimum and maximum of the DRC (see, e.g.…”

“…6,31 The typical shape of a DRC acquired during this process is displayed in Figure 1 for illustrative purposes. In the light of Dickinson et al, 8 it mainly depends on physical changes induced in the material by the ongoing welding process and can be roughly outlined into five stages, as well depicted by Adams et al 32 For the sake of conciseness, these stages can be summarized as influenced by two main concurrent effects due to (a) the metal electrical resistivity and (b) the contact area among the metal sheets to joint. These effects develop during the RSW process by means of the heat produced by the current flow and the clamping pressure generated by copper electrodes.…”

Functional clustering methods for resistance spot welding process data in the automotive industry

“…We observe that the minimum point abscissa is practically constant among centroids of Figure 4. According to the technological literature, 8,32 the local maximum (NF) is the landmark for the start of the nugget formation (see also Section 2 and the typical DRC behavior depicted in Figure 1). Therefore, we can state that spot welds corresponding to DRC centroids with smaller phase difference (II) have larger time interval between the local maximum and the end of the welding process (IV), that is, larger exposition time to the heat energy supplied for nugget growth, and thus, larger nugget size.…”

“…We observe that the minimum point abscissa is practically constant among centroids of Figure 4. According to the technological literature, 8,32 the local maximum (NF) is the landmark for the start of the nugget formation (see also Section 2 and the typical DRC behavior depicted in Figure 1). Therefore, we can state that spot welds corresponding to Resistance…”

An Experimental Study on Bipolar Tissue Hemostasis and Its Dynamic Impedance

“…An important variable in the tissue hemostasis process is electrical impedance, which varies during the process due to the water content and cell structural change. Equivalent to the dynamic resistance in resistance spot welding [30][31][32], this dynamic impedance has been used as a signal to control the bipolar hemostasis process. V€ allfors and Bergdahl [33,34] suggested that the dynamic impedance during a bipolar vessel sealing process could be divided into several stages and tissue coagulation formed when the impedance reached the minimum.…”