Stud Welding Process Research Articles

Simulation of capacitor discharge stud welding process and void formation

Dynamic behaviour and void formation of the capacitor discharge (CD) stud welding process are investigated through simulation and experiments. Mechanical and electrical models are coupled to predict the current and voltage waveform of the stud welding, and the calculated results show good agreement with the experiment results. The mechanism of void formation and the void trapping condition are explained using the void flow model. While the results of the void flow model show that removal of the void is almost impossible, partial improvement in void reduction is achieved by adjusting the short circuit current between 1200 and 1700 A.

Reliability of 3/8 in. Stud-Welded Deformed Bar Anchors Subject to Tensile Loads

During a test program on flange-to-flange connectors for double tees, the behavior of stud-welded deformed bar anchors (DBA) became in doubt after several weld failures occurred prematurely. Since DBAs are commonly used for connections in many other types of precast concrete members, their reliability had been assumed to be satisfactory. This paper describes a small investigation into why these brittle failures occurred and what changes could be made to the stud welding process to prevent them. For this purpose, sixty-nine 3/8 in. (9.52 mm) diameter stud-welded deformed anchor bars were tested in tension to fracture. The specimens were fabricated by four manufacturers from different parts of the United States to obtain a sample of weld quality in practice. The results show that 19 percent of the specimens fractured at the weld. The data also showed that nearly all the specimens that fractured at the weld were fabricated using a particular stud gun setting procedure. Based on the test results, quality control procedures and revised settings are recommended for stud welding of 3/8 in. (9.52 mm) diameter DBAs.