Impact and Fatigue Failure of Resistance Spot Welds

Resistance spot welds are used extensively in every modern vehicle to connect sheet metal pieces together. During normal operation of a vehicle, spot welds fatigue and finally fail. In the event of crash, spot welds are often the weakest link in separation of the vehicle structure. Fatigue life of spot welds from different grades of steels, aluminums and other materials, various welding schedules and layout were determined in our laboratory and analysis was provided for vehicle design. Characteristics in impact failure of spot welds under different impact speed were also studied in detail both theoretically and experimentally. Strain rate effect in impact failure strength of spot welds was the main focus. Failure mode of spot welds, e.g. interfacial mode or pull-out mode which could be due to inferior welding design, was investigated as well. The results provide invaluable technical information to auto industry.

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