Strength tests were performed to reveal the failure mechanisms of spot weld in lap-shear and cross tension test samples. It is shown the while the lap-shear (cross tension) sample is subjected to shear (normal) load at the structural level the failure mechanism at the spot weld is tensile (shear) mode at the materials level. Based on the observed failure mechanism, stress distribution is assumed and related to the far field load for the lap-shear and cross tension test samples. It appears that the failure load of the cross tension sample is 74 percent of the lap-shear sample based on the classical von Mises failure theory. The theoretical model is further extended to the mixed normal/shear loading condition. Data from strength tests as well as finite element numerical method are used to validate the model. Finally, the utility of the model in accessing the failure strength of spot welds is discussed.
Issue Section:
Technical Papers
1.
Ewing, K. W., Cheresh, M., Thompson, R., and Kukuchek, P., 1982, “Static and Impact Strengths of Spot-Welded HSLA and Low Carbon Steel Joints,” SAE Paper 820281.
2.
VandenBossche, D. J., 1977, “Ultimate Strength and Failure Mode of Spot Welds in High Strength Steels,” SAE paper 770214.
3.
Radaj
, D.
, 1989
, “Stress Singularity, Notch Stress and Structural Stress at Spot-Welded Joints
,” Eng. Fract. Mech.
, 34
(2
), pp. 495
–506
.4.
Radaj
, D.
, and Zhang
, S.
, 1993
, “On the Relations Between Notch Stress and Crack Stress Intensity in Plane Shear and Mixed Mode Loading
,” Eng. Fract. Mech.
, 44
(5
), pp. 691
–704
.5.
Zhang
, S.
, 2001
, “Approximate Stress Formulas for a Multiaxial Spot Weld Specimen
,” Weld. J. (Miami)
, 80
(8
) 201s–203s
201s–203s
.6.
Zhang
, S.
, 1999
, “Approximate Stress Intensity Factors and Notch Stresses for Common Spot-Welded Specimens
,” Weld. J. (Miami)
, 78
(5
), pp. 1735
–1795
.7.
Zhang
, S.
, 1999
, “Stress Intensities Derived from Stresses Around a Spot Weld
,” Int. J. Fract.
, 99
, pp. 239
–257
.8.
Zhang
, S.
, 1997
, “Stress Intensities at Spot Welds
,” Int. J. Fract.
, 88
, pp. 167
–185
.9.
Wung
, P.
, 2001
, “A Force-Based Failure Criterion for Spot Weld Design
,” Exp. Mech.
, 41
(4
), pp. 107
–113
.10.
Wung
, P.
, Walsh
, T.
, Ourchane
, A.
, Stewart
, W.
, and Jie
, M.
, 2001
, “Failure of Spot Welds Under In-Plane Static Loading
,” Exp. Mech.
, 41
(1
), pp. 100
–106
.11.
Zuniga, S., and Sheppard, S. D., 1997, “Resistance Spot Weld Failure Loads and Modes in Overload Conditions,” Fatigue and Fracture Mechanics: 27th Volume, ASTM STP 1296, R. S. Piascik, J. C. Newman, and N. E. Dowling, eds., American Society for Testing and Materials, pp. 469–489.
12.
Barkey
, M. E.
, and Kang
, H.
, 1999
, “Testing of Spot Welded Coupons in Combined Tension and Shear
,” Exp. Tech.
, 23
(5
), pp. 20
–22
.13.
Lee
, Y.
, Wehner
, T.
, Lu
, M.
, Morrissett
, T.
, Pakalnins
, E.
, 1998
, “Ultimate Strength of Resistance Spot Welds Subjected to Combined Tension and Shear
,” J. Test. Eval.
, 26
(3
), pp. 213
–219
.14.
Lin
, S. H.
, Pan
, J.
, Wu
, S.
, Tyan
, T.
, and Wung
, P.
, 2002
, “Failure Loads of Spot Welds under Combined Opening and Shear Static Loading Conditions
,” Int. J. Solids Struct.
, 39
, pp. 19
–39
.15.
Chao, Y. J., 2002, “Failure of Spot Weld: A Competition Between Crack Mechanics and Plastic Collapse,” Recent Advances in Experimental Mechanics—In Honor of Isaac M. Daniel, Kluwer Academic Publishers, pp. 245–256.
16.
Dowling, N. E., Mechanical Behavior of Materials, Prentice Hall, New Jersey.
17.
Zhang
, Z. L.
, Hauge
, M.
, Degard
, J.
, and Thaulow
, C.
, 1999
, “Determining Material True Stress-Strain Curve from Tensile Specimens With Rectangular Cross-Section
,” Int. J. Solids Struct.
, 36
, pp. 3497
–3516
.18.
ANSI/AWS/SAE/D8.9-97, 1997, Recommended Practices for Test Methods for Evaluating the Resistance Spot Welding Behavior of Automotive Sheet Steel Materials, American Welding Society, Miami.
19.
Zhou
, M.
, Hu
, S. J.
, and Zhang
, H.
, 1999
, “Critical Specimen Sizes for Tensile-Shear Testing of Steel Sheets
,” Weld. J. (Miami)
, 78
(9
), pp. 305s–312s
305s–312s
.20.
Materials and Applications, 1998, Part II, Welding Handbook, 4, 8th edition, American Welding Society.
21.
AWS D8.7-88, SAE J-1188, 1987, Recommended Practices for Automotive Weld Quality—Resistance Spot Welding, American Welding Society.
22.
Radaj, D., and Zhang, S., 1996, “Anschauliche Grundlagen fur Krafte und Spannungen in Punktgeschweisten Uberlappverbindungen, Konstruktion,” 48, pp. 65–71.
23.
Radaj, D., and Zhang, S., 1996, “Strukturspannungen am starren Kern in endlich berandeter Platte,” Konstruktion, 48, pp. 195–199.
24.
Sawhill, J. M., Jr., and Furr, S. T., “Spot Weldability Tests for High-Strength Steels,” SAE paper 810352.
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