Energy-based Beta Peak Extraction from Dynamic Resistance Curves

Abstract

Recently, the importance of welding monitoring is emerging, and in particular, many studies using characteristic values of dynamic resistance curves are being conducted. Among the characteristic values, β-peak, peak on the dynamic resistance curve, contains important information on the extent to which the nugget grows. A common way to extract the β-peak is to determine the local maximum point followed by the local minimum point in the dynamic resistance curve. However, for dynamic resistance curves where local extremum values are unclear, extracting the β-peak in this manner is difficult. Therefore, in this study, a method using heating energy for β-peak extraction was proposed. Heating energy is the energy used until the β-peak is reached. Typically heating energy does not significantly differ even if the welding conditions differ for the same material. Based on the results, the β-peak of the dynamic resistance curve without the clear peak was extracted, and 11 characteristic values were calculated. Among them, three values that had a high correlation with the nugget diameter were selected. Using these values, the nugget diameter was predicted through linear regression analysis.