Failure loads of spot welds under combined opening and shear static loading conditions

Lin, Shiyao; Pan, Jwo; Wu, S. David; Tyan, Tau; Wung, P.

doi:10.1016/s0020-7683(01)00187-1

Cited by 105 publications

(54 citation statements)

References 16 publications

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“…2003a;Chao. 2003b;Zuniga et al 1997;Lin et al 2003;Marya et al 2006;Lin et al 2002). For example, Chao (2003a) studied the ultimate tensile strength of resistance spot welds in mild steel subjected to combined loading tension and shear loads, and verified that a spot weld under cross-tensile loading fails at a lower load than a spot weld subject to lap-shear loading.…”

Section: Latin American Journal Of Solids and Structures 13 (2016) 21mentioning

confidence: 99%

“…Beyond an initial linear portion corresponding to the elastic behavior, the curve remains linear in the plastic portion until the maximum load, which is considered as the failure load. Indeed, when the displacement continues to increase, the load starts dropping gradually as the crack initiation occurs followed by its propagation along the circumference of the nugget as discussed by Lin et al (2002Lin et al ( , 2003. However, in order to bring down these curves in the FE-model, a failure criterion must be introduced.…”

Section: Deformed Shape and Load-displacement Curvesmentioning

confidence: 99%

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Finite Element Method Based Modeling of Resistance Spot-Welded Mild Steel

Zaoui

Hadjoui

2016

Lat. Am. j. solids struct.

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This paper deals with Finite Element refined and simplified models of a mild steel spot-welded specimen, developed and validated based on quasi-static cross-tensile experimental tests. The first model was constructed with a fine discretization of the metal sheet and the spot weld was defined as a special geometric zone of the specimen. This model provided, in combination with experimental tests, the input data for the development of the second model, which was constructed with respect to the mesh size used in the complete car finite element model. This simplified model was developed with coarse shell elements and a spring-type beam element was used to model the spot weld behavior. The global accuracy of the two models was checked by comparing simulated and experimental load-displacement curves and by studying the specimen deformed shapes and the plastic deformation growth in the metal sheets. The obtained results show that both fine and coarse finite element models permit a good prediction of the experimental tests.

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Section: Latin American Journal Of Solids and Structures 13 (2016) 21mentioning

confidence: 99%

Section: Deformed Shape and Load-displacement Curvesmentioning

confidence: 99%

Finite Element Method Based Modeling of Resistance Spot-Welded Mild Steel

Zaoui

Hadjoui

2016

Lat. Am. j. solids struct.

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“…From the test conducted in Ref. 12, it was found that et and IX are also equal to 2 for a small tlr ratio (< 0.3). For large thickness-to-radius ratios, a value different from 2 is possible.…”

Section: Empirical Formula For Stiffness and Strengthmentioning

confidence: 99%

A force-based failure criterion for spot weld design

Wung

2001

Experimental Mechanics

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ABSTRACT--This paper suggests a very simple, force-based formula that combines four failure modes into one dimensionless equation to govern spot weld failure under general static loading conditions. The four failure modes are shear, rotation, normal and peel. The normal separation mode and the peel mode are corresponding to mode I (opening mode). The tensile/shear mode is mode II (sliding mode), and the in-plane rotation mode is mode III (tearing mode). Test coupons and test fixtures are designed and tested to establish and verify this equation. To further verify this equation, a long difficult to understand automotive spot weld failure problem was studied. Applying finite element-calculated resultant loads to the proposed formula resulted in analytical values that correlated very well with the long time field observed spot weld failures. This analytical prediction reasonably explained the spot weld failure mechanism and provided good design directions to improve the durability of the auto structure.KEY WORDS--Spot weld, complete failure modes, forcebased failure criterion, semi-empirical method, test coupon for verificationTo understand and accurately predict spot weld failure is very important in auto body shell structure design. Numerous efforts have been devoted to estimating the fatigue life of spot welds.I-4 Few stress-based multiaxial failure criteria 5-7 have been published for spot weld fatigue failure prediction. These criteria, in general, are based on high-cycle/low-stress fatigue tests for the overlap shear mode and peel mode only. Spot weld failure criteria for the low-cycle/high-stress, normal separation mode and in-plane rotation modes are extremely rare. Spot weld designs using these criteria with simplified finite element modeling earl lead to (1) underestimated stresses by rigid bar simulation, (2) lack of data support for high-stress/low-cycle failure, and (3) incomplete failure mode consideration. Due to geometric complexity and material nonhomogeneity, it is impractical to accurately model each spot weld using detailed solid elements, since about 5000 to 11000 quadratic solid elements are required. Currently, in the automotive industry, the most common method of modeling a spot weld is to use rigid-bar links. A spot weld, in spite of the fact that it is not a slender structure, is modeled as a rigid bar. By definition, the dependent node of a rigid bar would follow the independent node in the specified degree of freedom that artificially constrains the local deformation of the rigid bar in the coupled degree of freedom. Apparently, Engineer, MD44 AEC Building, Ford Motor Company, Dearborn, MI 48121. Original manuscript submitted." August 16, 2000. Final manuscript received: November 1, 2000 this modeling technique cannot provide correct strains and stresses in the vicinity of the spot weld. On the other hand, due to cost-saving considerations, auto industries do require simple finite element model representation of spot welds. P. Wung is a ResearchIn addition to the finite element modeli...

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“…Validation of existing spot-weld failure criteria has been explored with analytical approaches wherein the stress distribution around a weld is related to the far field failure load [14,15,[18][19][20][21][22][23] and with finite element failure simulations [24,25]. There are numerous reports in the literature aimed at predicting failure of spot welds under various loading conditions such as tension [23], shear [23], combined tensile/shear [16,23,26], impact [27], and fatigue [28,29]. Test specimens with different geometries (e.g.…”

Section: Introductionmentioning

confidence: 99%

Mode I Fracture at Spot Welds in Dual-Phase Steel: An Application of Reverse Digital Image Correlation

et al. 2010

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Strain fields in 600 grade dual-phase steel V-notch tensile specimens, both with and without a spot weld, were measured after mode I fracture initiation. Starting with the final image of a fully developed crack, a novel reverse digital image correlation (DIC) analysis was used to determine the path that the crack followed at the onset of fracture as well as the crack tip deformation field. This gave the pixel coordinates of grid points on both sides (i.e. fracture surfaces) of the crack path in the undeformed image. Strain fields that develop in the base material regions surrounding the two fracture surfaces were subsequently measured with forward DIC analysis. Steady state values of the crack tip opening displacement (CTOD) and crack tip opening angle (CTOA), which are important fracture parameters, were measured for the base DP600 metal. Notch tip opening displacement (NTOD) and notch tip opening angle were also measured. It was found that steady state values of the CTOD and CTOA are reached within 2 mm or so of crack growth following completion of the flat-to-slant transition of the fracture surface and stabilization of the crack tunneling effect.

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Failure loads of spot welds under combined opening and shear static loading conditions

Cited by 105 publications

References 16 publications

Finite Element Method Based Modeling of Resistance Spot-Welded Mild Steel

Finite Element Method Based Modeling of Resistance Spot-Welded Mild Steel

A force-based failure criterion for spot weld design

Mode I Fracture at Spot Welds in Dual-Phase Steel: An Application of Reverse Digital Image Correlation

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