scholarly journals Finite element analysis of residual stress generation during spot welding and its affect on fatigue behavior of spot welded joints

2005 ◽  
Author(s):  
◽  
Xin Long

This dissertation presents the finite element based prediction of residual stress generation in a spot welded joint during the spot welding process and the effects of residual stress on fatigue behavior of a spot welded joint. Spot welded advanced high strength steels, namely dual phase DP600 GI and transformation induced plasticity TRIP600 steels were investigated for their fatigue life, microstructure changes and fatigue fracture mechanisms to develop design data for possible application in future light weight and more fuel efficiency automobiles.

2016 ◽  
Vol 707 ◽  
pp. 154-158
Author(s):  
Somsak Limwongsakorn ◽  
Wasawat Nakkiew ◽  
Adirek Baisukhan

The proposed finite element analysis (FEA) model was constructed using FEA simulation software, ANSYS program, for determining effects of corrosion fatigue (CF) from TIG welding process on AISI 304 stainless steel workpiece. The FEA model of TIG welding process was developed from Goldak's double ellipsoid moving heat source. In this paper, the residual stress results obtained from the FEA model were consistent with results from the X-ray diffraction (XRD) method. The residual stress was further used as an input in the next step of corrosion fatigue analysis. The predictive CF life result obtained from the FEA CF model were consistent with the value obtained from stress-life curve (S-N curve) from the reference literaturature. Therefore, the proposed FEA of CF model was then used for predicting the corrosion fatigue life on TIG welding workpiece, the results from the model showed the corrosion fatigue life of 1,794 cycles with testing condition of the frequency ( f ) = 0.1 Hz and the equivalent load of 67.5 kN (equal to 150 MPa) with R = 0.25.


Author(s):  
Shivdayal Patel ◽  
B. P. Patel ◽  
Suhail Ahmad

Welding is one of the most used joining methods in the ship industry. However, residual stresses are induced in the welded joints due to the rapid heating and cooling leading to inhomogenously distributed dimensional changes and non-uniform plastic and thermal strains. A number of factors, such as welding speed, boundary conditions, weld geometry, weld thickness, welding current/voltage, number of weld passes, pre-/post-heating etc, influence the residual stress distribution. The main aim of this work is to estimate the residual stresses in welded joints through finite element analysis and to investigate the effects of boundary conditions, welding speed and plate thickness on through the thickness/surface distributions of residual stresses. The welding process is simulated using 3D Finite element model in ABAQUS FE software in two steps: 1. Transient thermal analysis and 2. Quasi-static thermo-elasto-plastic analysis. The normal residual stresses along and across the weld in the weld tow region are found to be significant with nonlinear distribution. The residual stresses increase with the increase in the thickness of the plates being welded. The nature of the normal residual stress along the weld is found to be tensile-compressive-tensile and the nature of normal residual stress across the weld is found to be tensile along the thickness direction.


2011 ◽  
Vol 314-316 ◽  
pp. 428-431 ◽  
Author(s):  
Hui Du ◽  
Dong Po Wang ◽  
Chun Xiu Liu ◽  
Hai Zhang

To simulate preheating and postweld heat treatment of Q345 steel pipe welding, the finite element model was established. The welding process was simulated by method of the ANSYS element birth and death technique. In this paper, to obtain the distribution of the temperature field and stress field in different situations, preheating processes with two different values of temperature and postweld heat treatment process were simulated respectively. The results show that preheating can homogenize residual stress distribution of the weldment and decrease the residual stress. The heat treatment reduces the residual stress in inner and outer walls by 24% and 70% respectively and the stress distribution is more even and stress concentration is reduced.


2006 ◽  
Vol 129 (1) ◽  
pp. 95-100 ◽  
Author(s):  
B. H. Chang ◽  
D. Du ◽  
B. Sui ◽  
Y. Zhou ◽  
Z. Wang ◽  
...  

Using experimental and finite element analysis methods, the effects of electrode forging force are investigated on fatigue behavior and residual stress of spot welded joints of aluminum alloy 5182. Results show that applying forging force significantly reduces the residual stresses in the heat affected zone and the fatigue cracks no longer initiate from there; instead, all cracks begin from the nugget edge. In addition, the mitigation of residual stress by forging force decreases the driving force for crack propagation and leads to longer fatigue life. It can be concluded that applying forging force appropriately has a positive effect on the fatigue strength of resistance spot welded joints.


2008 ◽  
Vol 580-582 ◽  
pp. 625-628
Author(s):  
Bok Kyu Lim ◽  
Min Gun Kim ◽  
Ku Hyun Chung ◽  
Dong Youl Kim ◽  
Young Woo Choi

The stability of plate structure is a very critical problem. The spot welding is practically designed by experiential decisions; so, it is inefficient and risks fatigue fracture. In real structure, multi-spot welded joints are more frequently used than single-spot welded joint. The fatigue behavior of multi-spot welded joints is different from that of single-spot welded joints. The fatigue lives of spot-welding specimen and multi points spot-welding structure are predicted using a FEMFAT 4.4e based on the linear finite element analysis. It is necessary to establish a reasonable and systematic design criterion for the long life design of the spot-welding body structure. In this study, relative location of spot welding was chosen as parameter and the stress distribution around the spot-welding joints’ subjected tensile load was numerically analyzed.


2015 ◽  
Vol 799-800 ◽  
pp. 428-433 ◽  
Author(s):  
Somsak Limwongsakorn ◽  
Wasawat Nakkiew ◽  
Adirek Baisukhan

Residual stress occured in welding process generally causes reduction in the strength of welded joints, shortens the fatigue life, and brings about the distortion of the workpiece. In this research, finite element analysis (FEA) model of the butt-joint tungsten inert gas (TIG) welding process with the application of birth-death technique was presented. The material used in this research was AISI 304 stainless steel. The FEA model was constructed on a simulation software, ANSYS. The predictive residual stress from a welding condition obtained from the FEA model was verified by the value measured from X-ray diffraction (XRD) machine. Effects of four welding process parameters: efficiency, welding speed, arc current, and arc voltage on residual stress at the center of the welded joint and at the heated affected zone (HAZ) were investigated. The welding conditions were generated by varying these four main effects according to the Taguchi design of experiment technique (L8 orthogonal array). In general, compressive residual stress is beneficial to the strength and fatigue life of welded joints. For the Taguchi method the larger is better constraint was used; larger means higher magnitude of compressive residual stress. The predictive residual stress results obtained from the FEA model were consistent with the values obtained from the XRD measurement. The result suggested that the most significant effect was the arc current, followed by the arc voltage, welding speed, and the efficiency. The response optimizer in MINITAB software showed the optimal magnitude of compressive residual stress values of about 52 MPa obtained at the arc current of 126 Ampere, arc voltage of 17 Volts, welding speed of 110 mm/min, and the efficiency of 80%.


2008 ◽  
Vol 580-582 ◽  
pp. 291-294
Author(s):  
Zhi Guo Gao ◽  
Jian Huang ◽  
Yi Xiong Wu

For many years, rivet joint technology has been applied in the automotive and aerospace industry. Recently, it began to apply laser welding technology to lap joints instead of rivet joining. Laser spot welding has some potential advantages including time saving, cost reduction, material saving and weight reducing. A lap joint of aluminum alloy LY12 with different plate thickness, namely 2mm and 1mm, was spot-welded by CO2 laser. For the welding, laser power in pulse form with ramping-up and cooling-down shape was used, and pure helium gas served as shielding gas to fill around welding area. In this study transient three-dimensional non-linear finite element modeling was used to analyze heat flow and residual stress of the laser spot welding of aluminum alloy LY12. In modeling the temperature dependence of material properties, influence of contact surfaces are taken into account. To analyze, Gaussian distributed heat source model and thermo-elasto-plastic behavior were applied. Weld dimensions and residual stress at the weld surface were calculated numerically and compared with the experimental results.


2007 ◽  
Vol 185 (1-3) ◽  
pp. 160-165 ◽  
Author(s):  
Zhigang Hou ◽  
Ill-Soo Kim ◽  
Yuanxun Wang ◽  
Chunzhi Li ◽  
Chuanyao Chen

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