Residual stresses in resistance spot welding: Comparison of simulation and measured results

Conference · Sat Dec 31 04:00:00 EST 1994

OSTI ID:115428

Sheppard, S; Syed, M ^[1]

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1. Stanford Univ. CA (United States)

Numerical simulations of welding processes offer researchers and engineers the opportunity to study in detail thermal and mechanical histories created by welding. The objective of this work is to explore the influence of the dynamically changing contact patch size on thermal and mechanical histories in resistance spot welding. To this end, a fully coupled electrical-thermal-mechanical simulation of RSW has been developed. The simulation considers welding and the subsequent cooling of the workpiece. The results of such a simulation are presented for the case of HSLA galvanized sheet and are compared with numerical results where such a coupling was not included. In particular, thermal histories and the final states of residual stresses are compared. Specifically, the fully coupled simulation results show that: (1) There is a 44% reduction in contact area at the faying surface as welding progresses. (2) There are substantial (near yield strength) residual stresses in the annulus surrounding the weld nugget. (3) Cooling rates in the nugget are on the order of 10,000{degrees}F/s when welding with electrode hold time. Rates are closer to 1000{degrees}F/s when there is no electrode hold time. (4) predicted residual stresses compare favorably with measured values. Note that it is extremely difficult (if not impossible) to make residual stress measurements in the area of greatest concern with regards to weld fatigue failure. The predicted residual stresses will be valuable input to engineers and researchers concerned with the fatigue performance of resistance spot welded structures.

• OSTI ID: 115428
• Report Number(s): CONF-9404233--
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
COMPUTERIZED SIMULATION
COOLING
ELECTRODES
FATIGUE
RESISTANCE WELDING
STRESS ANALYSIS
WELDED JOINTS
YIELD STRENGTH