Abstract: Spot welds are evaluated using stress-wave emission techniques by measuring the stress-wave energy emitted from the weld area during n time intervals of the weld cycle, where n.gtoreq.4. Each of the time intervals corresponds to a different aspect of the weld cycle such as, for example, the initiation of heating, the separate solid-to-liquid phase transformation in each of the articles being welded, material combination within the weld nugget, cooling stresses occurring during resolidification, and post-weld cracking. The energy values obtained for each of the time interval can be compared with predetermined acceptable energy value ranges for corresponding ones of the intervals and/or compared with predetermined ratio values between two or more of the obtained interval values to determine the quality of a weld.

Abstract: A windable resistance-capacitance (R-C) network having at least three terminals and formed of adjacent first and second alternating layers of dielectric and electrically conductive low-resistance material is disclosed, in which discrete resistance and capacitance network elements of predetermined value are interconnected and formed by removing portions of the layers of conductive material along appropriately positioned lines. The present network can be economically mass produced and the formed resistance and capacitance elements exhibit a minimal distributive effect.