Abstract
Failure loads of spot weld specimens are investigated under impact combined loading conditions. A set of test fixtures was designed and used to obtain failure loads of mild steel spot weld specimens under combined opening and shear loading conditions. Three different impact speeds were applied to examine the effects of separation speed on failure loads. Micrographs of the cross-sections of failed spot welds were obtained to understand the failure processes in mild steel specimens under different impact combined loads. The experimental results indicate that the failure mechanisms of spot welds are very similar for mild steel specimens at various impact speeds. These micrographs show that the sheet thickness can affect the failure mechanisms. For 1.0 mm specimens, the failure occurs near the base metal in a necking/shear failure mode. For 1.5 mm specimens, the failure occurs near the heat-affected zone in a shear failure mode. Based on the experimental results, the effects of the inertia force, the separation speed, and the loading angle on the failure loads of spot welds are investigated. Failure criteria are proposed to characterize the failure loads of spot welds under impact combined opening and shear loads for engineering applications. The failure load can be expressed as a function of the tensile strength of the base metal, the nugget size, the sheet thickness, the maximum separation speed, the loading angle, and empirical coefficients for a given welding schedule.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Hartmann, E.C., “Mechanical Tests of Spot Welds,” Welding Journal,37, 520s-523s (1958).
Davidson, J.A., “A Review of the Fatigue Properties of Spot-Welded Sheet Steels, SAE Technical Paper. No. 830033, Society of Automotive Engineers, Warrendale, PA (1983).
Radaj, D., “Stress Singularity, Notch Stress and Structural Stress at Spot-Welded Joints,” Engineering Fracture Mechanics,34, 495–506 (1989).
Swellam, M.H., Banas, G., and Lawrence, F.V., “A Fatigue Design Parameter for Spot Welds,” Fatigue and Fracture of Engineering Materials & Structures,17, 1197–1204 (1994).
Wang, P.-C. and Ewing, K.W., “Fracture Mechanics Analysis of Fatigue Resistance of Spot Welded Coach-Peel Joints,” Fatigue and Fracture of Engineering Materials and Structures,14, 913–930 (1991).
Zhang, S., “Recent Developments in Analysis and Testing of Spot Welds,” SAE Technical Paper No. 2001-01-0432, Society of Automotive Engineers, Warrendale, PA (2001).
Sheppard, S.D. and Pan, N., “A Look at Fatigue: Is Resistance Spot Welds-Notch or Crack? SAE Technical Paper No. 2001-01-0433, Society of Automotive Engineers, Warrendale, PA (2001).
VandenBossche, D.J., “Ultimate Strength and Failure Mode of Spot Welds in High Strength Steels,” SAE Technical Paper, No. 770214, Society of Automotive Engineers, Warrendale, PA (1977).
Sawhill, I.M. and Furr, S.T., “Spot Weldibility Tests for High-Strength Steels,” SAE Technical Paper, No. 810352, Society of Automotive Engineers, Warrendale, PA (1981).
Ewing, K.W., Cheresh, M., Thompson, R. and Kukuchek, P., “Static and Impact Strengths of Spot Welded HSLA and Low Carbon Steel Joints,” SAE Technical Paper, No. 820281, Society of Automotive Engineers, Warrendale, PA (1982).
Zuniga, S. and Sheppard, S.D., “Resistance Spot Weld Failure Loads and Modes in Overload Conditions,” Fatigue and Fracture Mechanics, ASTM STP 1296, Piascik, R. S., Newman, J. C. and Dowling, N. E., editors, American Society for Testing and Materials, 469–489 (1997).
Lee, Y.-L., Wehner, T.J., Lu, M.-W. Morrissett, T.W., and Pakalnins, E., “Ultimate Strength of Resistance Spot Welds Subjected to Combined Tension and Shear,” Journal of Testing and Evaluation,26, 213–219 (1998).
Wung, P., “A Force-Based Failure Criterion for Spot Weld Analysis,” EXPERIMENTAL MECHANICS,41, 107–113 (2001).
Wung, P., Walsh, T., Ourchane, A., Stewart, W., and Jie, M., “Failure of Spot Welds Under In-Plane Static Loading,” EXPERIMENTAL MECHANICS,41, 100–106 (2001).
Lin, S.-H., Pan, J., Wu, S.-R., and Tyan, T., “Spot Weld Failure Loads Under Combined Mode Loading Conditions,” SAE Technical Paper No. 2001-01-0428, Society of Automotive Engineers, warrendale, PA (2001).
Lin, S.-H., Pan, J., Tyan, T., Wu, S.-R., and Prasad, P., “Modeling and Testing of Spot Welds under Dynamic Impact Loading Conditions,” SAE Technical Paper No. 2002-01-0149, Society of Automotive Engineers, Warrendale, PA (2002).
Lin, S.-H., Pan, J., Wu, S.-R., Tyan, T., and Wung, P., “Failure Loads of Spot Welds under Combined Opening and Shear Static Loading Conditions,” International Journal of Solids and Structures,39, 19–39 (2002).
Lin, S.-H., Pan, J., Tyan, T., and Prasad, P., “A General Circumferential Failure Criterion for Spot Welds under Combined Loading Conditions,” International Journal of Solids and Structures, submitted (2003).
Wung, P. and Stewart, W., “Method of Analyzing Spot Welded Structures,” US Patent No. 6,186,011 B1 (2001).
Heuschkel, J., “The Expression of Spot-Weld Properties,” Welding Journal,31, 931–943 (1952).
Hosford, W.F. and Caddell, R.M., “Metal Forming: Mechanics and Metallurgy,” 2nd edition, Prentice-Hall, Englewood Cliffs, NJ (1993).
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Lin, S.H., Pan, J., Wu, S. et al. Failure loads of spot weld specimens under impact opening and shear loading conditions. Experimental Mechanics 44, 147–157 (2004). https://doi.org/10.1007/BF02428174
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF02428174