G0301104 Influence of Variation of Nugget Diameter and Spot Welding Location on Fatigue Life of Spot Welded Joint

2015 ◽  
Vol 2015 (0) ◽  
pp. _G0301104--_G0301104-
Author(s):  
Masaki WASHIO ◽  
Chihiro TAKATUSUKA ◽  
Noboru TOMIOKA ◽  
Akifumi OKABE
Keyword(s):  
Fatigue Life ◽  
Spot Welding ◽  
Welded Joint ◽  
Nugget Diameter ◽  
Spot Welded

scholarly journals A Nondestructive Evaluation Method: Measuring the Fixed Strength of Spot-Welded Joint Points by Surface Electrical Resistivity

2013 ◽  
Vol 135 (2) ◽  
Author(s):  
Akira Shimamoto ◽  
Keitaro Yamashita ◽  
Hirofumi Inoue ◽  
Sung-mo Yang ◽  
Masahiro Iwata ◽  
...  
Keyword(s):  
Welded Joints ◽  
Electrical Resistance ◽  
Spot Welding ◽  
Evaluation Method ◽  
Welded Joint ◽  
Nondestructive Method ◽  
Nugget Diameter ◽  
Two Factors ◽  
Surface Electrical Resistance ◽  
Spot Welded

Destructive tests are generally applied to evaluate the fixed strength of spot-welding nuggets of zinc-plated steel (which is a widely used primary structural material for automobiles). These destructive tests, however, are expensive and time-consuming. This paper proposes a nondestructive method for evaluating the fixed strength of the welded joints using surface electrical resistance. A direct current nugget-tester and probes have been developed by the authors for this purpose. The proposed nondestructive method uses the relative decrease in surface electrical resistance, α. The proposed method also considers the effect of the corona bond. The nugget diameter is estimated by two factors: RQuota, which is calculated from variation of resistance, and a constant that represents the area of the corona bond. Since the maximum tensile strength is correlated with the nugget diameter, it can be inferred from the estimated nugget diameter. When appropriate measuring conditions for the surface electrical resistance are chosen, the proposed method can effectively evaluate the fixed strength of the spot-welded joints even if the steel sheet is zinc-plated.

scholarly journals Rapid fatigue life prediction for spot-welded joint of SUS301 L-DLT stainless steel and Q235B carbon steel based on energy dissipation

2018 ◽  
Vol 10 (11) ◽  
pp. 168781401881101 ◽  
Author(s):  
Yaliang Liu ◽  
Yibo Sun ◽  
Yang Sun ◽  
Hongji Xu ◽  
Xinhua Yang
Keyword(s):  
Stainless Steel ◽  
Fatigue Life ◽  
Carbon Steel ◽  
Energy Dissipation ◽  
Life Prediction ◽  
Welded Joint ◽  
Fatigue Behavior ◽  
Dissimilar Materials ◽  
Fatigue Life Prediction ◽  
Spot Welded

Spot welding of dissimilar materials can utilize the respective advantage comprehensively, of which reliable prediction of fatigue life is the key issue in the structure design and service process. Taking into account almost all the complex factors that have effects on the fatigue behavior such as load level, thickness, welding nugget diameter, vibrational frequency, and material properties, this article proposed an energy dissipation-based method that is able to predict the fatigue life for spot-welded dissimilar materials rapidly. In order to obtain the temperature gradient, the temperature variations of four-group spot-welded joint of SUS301 L-DLT stainless steel and Q235 carbon steel during high-cycle fatigue tests were monitored by thermal infrared scanner. Specifically, temperature variation disciplines of specimen surface were divided into four stages: temperature increase, temperature decrease, continuous steady increase in temperature, and ultimate drop after the fracture. The material constant C that a spot-welded joint of dissimilar material needs to reach fracture is 0.05425°C·mm3. When the specimen was applied higher than the fatigue limit, the highest error between experimental values and predicted values is 18.90%, and others are lower than 10%. Therefore, a good agreement was achieved in fatigue life prediction between the new method and the validation test results.

A Non-Destructive Evaluation Method: Measuring the Fixed Strength of Spot Welded Joint Points by Surface Electric Resistivity

2010 ◽  
Author(s):  
Akira Shimamoto ◽  
Keitaro Yamashita ◽  
Hirofumi Inoue ◽  
Sung-mo Yang ◽  
Masahiro Iwata ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Spot Welding ◽  
Evaluation Method ◽  
Welded Joint ◽  
Electric Resistivity ◽  
Electric Resistance ◽  
Non Destructive Evaluation ◽  
Nugget Diameter ◽  
Zinc Plating ◽  
Non Destructive

Destructive tests are generally applied for evaluating fixed strength of spot welding nuggets on zinc plating steel, which is swidely used as the primary automobile structural material. Destructive tests, however, are expensive and time consuming. This paper discusses a non-destructive method for evaluating of welded joints fixed strength by utilizing surface electric resistance. A nugget tester has developed by authors for this purpose. The non-destructive method focuses on surface electric resistance decreasing rate; α, and effect of the corona bond. Nugget diameter is estimated by RQuota calculated from variation of resistance and constant representing the area of the corona bond. Since maximum tensile strength is correlated with the nugget diameter, it is inferred from the estimated nugget diameter.

Effect of Strain Rate Variation on Fatigue Life of Spot Welded Joint

2005 ◽  
Vol 297-300 ◽  
pp. 2447-2452
Author(s):  
Joon Hyuk Song ◽  
Hyu Sun Yu ◽  
Hee Yong Kang ◽  
Sung Mo Yang
Keyword(s):  
Life Cycle ◽  
Fatigue Life ◽  
Strain Rate ◽  
Welded Joint ◽  
Welding Current ◽  
Dynamic Strain ◽  
Rate Variation ◽  
Welding Condition ◽  
Rate Region ◽  
Spot Welded

Resistance spot welding is used extensively to fasten sheet for automotive applications. In many components, these welds should maintain their integrity under severe loading conditions. However fatigue strength of the spot welded joint is considerably lower than base metal due to stress concentration at the nugget edge, and is influenced by its geometrical and mechanical factors such as welding condition and etc. In this paper, it is estimated that effect of strain rate variation on fatigue life of spot welded joint. The analytical method proposed to overcome above difficult using lethargy coefficient concept for evaluating the fatigue life cycle of spot welded joint. The reliability of the life cycle is completed by comparing with the life cycle obtained by fatigue test for the specimen with the welding current. And the above procedure is numerically extended to get the life of dynamic strain rate region.

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