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.

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.

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

A New Method of Stress Calculation in Spot Welded Joint and Its Application to Fatigue Life Prediction of Actual Vehicle

2003 ◽  
Author(s):  
Kazuhiro Seto ◽  
Eisuke Nakayama ◽  
Koichi Tsunoda ◽  
Nobuhiro Fujita ◽  
Yuichi Yoshida ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Life Prediction ◽  
Welded Joint ◽  
Fatigue Life Prediction ◽  
New Method ◽  
Stress Calculation ◽  
Spot Welded

EFFECT OF FATIGUE TEST ON SPOT WELDED STRUCTURAL JOINT

2017 ◽  
Vol 79 (5-2) ◽  
Author(s):  
Mohammad Khalid Wahid ◽  
Muhammad Nabil Muhammed Sufian ◽  
Mohamed Saiful Firdaus Hussin
Keyword(s):  
Life Cycle ◽  
Fatigue Life ◽  
Fatigue Strength ◽  
Spot Welding ◽  
Fatigue Testing ◽  
Fatigue Stress ◽  
Component Design ◽  
Welded Structure ◽  
Different Thickness ◽  
Spot Welded

Spot welding is mainly used method in joining sheet metals for body structure in automotive industry. The comprehension of the fatigue strength for the spot welds is very critical in automotive component design. Parameter for the resistance spot welding and fatigue machines is constant for each specimen used. The S-N curve is obtained from the fatigue testing for each specimen. This experiment parameters are varies the different thickness and different material combination in spot welding structure to investigate the fatigue life cycle and fatigue stress. For 1050A aluminium joint, fatigue life cycle and fatigue strength will decrease from number of cycle 500 at 16.58 MPa to number of cycle 61 at 6.62 MPa as the thickness increase. The fatigue life cycle and fatigue stress for galvanized iron will increase from number of cycle  46 at 9.25 MPa to number of cycle  1500 at 57.8 MPa when the thickness of joint increase. The finding from the combination of 1050A aluminum and galvanized iron on spot welded structure has shown no improvement in term of fatigue life cycle and fatigue strength because specimens experienced failure at number of cycle 19 with fatigue stress 2.36 MPa.

Dynamic Strain Ageing in a Twin-Induced Plasticity Steel

2013 ◽  
Vol 750 ◽  
pp. 88-91 ◽  
Author(s):  
Jiang Ying Meng ◽  
Li He Qian ◽  
Peng Cheng Guo ◽  
Fu Cheng Zhang
Keyword(s):  
Strain Rate ◽  
Critical Strain ◽  
Tensile Tests ◽  
Dynamic Strain ◽  
Dynamic Strain Ageing ◽  
Serrated Flow ◽  
Strain Behavior ◽  
Rate Region ◽  
Lower Strain ◽  
Twip Steels

This work was to clarify the characteristics of serrated flow in an austenitic FeMnC twin-induced plasticity (TWIP) steel at room temperature (RT) using both strain- and crosshead displacement-controlled tensile tests. Three types of serrations were observed in strain-controlled but not in displacement-controlled tests, indicating that strain-controlled tensile tests provide more deformation details. The occurrence of the different types of serrations depends on both strain rate and strain level. Type C serrations were observed in TWIP steels at RT for the first time. The critical strain for the onset of serrations exhibits a positive strain rate dependence at higher strain rates, whereas an “inverse” critical strain behavior was observed in the lower strain rate region.

Fatigue Life of Multi-Lap Welding of Automotives Steel Sheet by QSTS

2008 ◽  
Vol 33-37 ◽  
pp. 151-156
Author(s):  
Seung Chul Shin ◽  
Sung Mo Yang ◽  
Hyo Sun Yu ◽  
Hee Yong Kang ◽  
Chae Won Kim
Keyword(s):  
Life Cycle ◽  
Fatigue Life ◽  
Welded Joints ◽  
Fuel Efficiency ◽  
Life Extension ◽  
Steel Sheets ◽  
Whole Process ◽  
Lap Welding ◽  
Automotive Steel ◽  
Spot Welded

This paper shows how the number of lap of spot welded joints in automotive steel sheets changes the life -cycle transform of itself. There has been significant developments in the life extension of automotive steel sheets, as well as in passenger safety. We verified the validity of the S-N curve of materials by QSTS test. Moreover, we used EZNCEN and HS40R, which are commonly used as automotive steel sheets because of their excellence in increasing fuel efficiency. The purpose of research was to compare the fatigue life of multi - lap of spot welded joints to there. In addition s, we used the two different kinds of sheets together in the same welding under the same condition. Through this whole process, the hypothesis on the life cycle of lethargy coefficients was found to be in good agreement with the result of the experiment. That is, when using sheets of the same materials in one welding, the fatigue life of two laps of a spot welded joint was found to be much superior by EZNCEN 5~14%, HS40R 17~30%,and when using each sheet of different materials, we found the decrease in fatigue life by 6~16%. Finally, the best value from the data was chosen based on the experiment for the analysis of the fatigue life of each layer.

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