Investigation of the effect of sheet thickness on residual stresses in resistance spot welding of aluminum sheets

Sedighi, M.; Afshari, Davood; Nazari, Farshad

doi:10.1177/0954406216685124

Cited by 24 publications

(7 citation statements)

References 20 publications

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“…37 In case of thicker sheet, the bead volume should be more than that of thin sheet to make a sufficiently strong joint and as a result of which the residual stresses would increase in case of thick sheet. In case of resistance spot welding of aluminum sheet, same kind of observations was made by Sedighi et al 38 Basically, thin wires and sheets are used for delicate applications in the field of MEMS and biomedical. On the other hand, the requirements of thick sheets and big diameter wires are vital for different structural applications.…”

Section: Introductionmentioning

confidence: 73%

Study on mechanical performance of laser-welded NiTinol sheet

Datta

Raza

Saha

et al. 2020

Proceedings of the Institution of Mechanical Engineers, Part B:

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NiTinol, because of its several superior properties like shape memory effect, pseudoelasticity, corrosion resistance and biocompatibility, has become a promising member for various application areas including biomedical, micro-electro-mechanical system and aerospace. Poor machinability, lack of joining techniques and high cost of the material are presently restricting the use of the material in practical applications to its full potential. Laser welding is the majorly used fabrication technique for this material. The effects of welding on the bead geometry, microstructure, new phase formation, phase transformation temperature for laser welding of 2-mm thick NiTinol sheet in bead-on-plate configuration were investigated through this study using Yb-fiber laser in continuous mode of operation. Moreover, the mechanical properties of the joint were assessed by means of tensile tests and cyclic loading–unloading test. The functionality of the cyclic loading–unloading was tested by analysis of the mechanical hysteresis response up to 6% strain levels. Furthermore, the fractured surface was analyzed by scanning electron microscopy. Results revealed that the microstructure varied across the different zones of welding depending on temperature gradient and solidification rate. The microhardness value of the weld-bead was reduced considerably from that of the parent material. Brittle intermetallic compounds of Ti and Ni were formed during welding. It was also found that the welding greatly influenced the phase transformation temperature, overall mechanical behavior and the mode of failure in comparison with parent material.

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Section: Introductionmentioning

confidence: 73%

Study on mechanical performance of laser-welded NiTinol sheet

Datta

Raza

Saha

et al. 2020

Proceedings of the Institution of Mechanical Engineers, Part B:

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“…where T is the fluid temperature in K. The above equations are valid in the temperature range from 0 • C to 100 • C and are the same as those used in the in-house program. Similarly, the properties of aluminum (specific heat and thermal conductivity) were introduced into the model according to the following equations [35]:…”

Section: D Cfd Modelmentioning

confidence: 99%

Mathematical Model of a Sun-Tracked Parabolic Trough Collector and Its Verification

2020

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The paper presents a one-dimensional distributed parameter model for simulating the transient-state operation of a parabolic trough collector (PTC). The analyzed solar collector has a module design and is equipped with a two-axis sun-tracking system to increase the solar energy yield. The single module is composed of an evacuated tube and a set of parabolic mirrors acting as reflectors. In each of the collector tubes, two aluminum U-tubes are installed, enabling heat intake by the solar fluid. The collector is intended for household applications, as well as other medium thermal energy demand uses. During the numerical model development, appropriate energy balance differential equations are formulated for the collector individual components. The equations are solved using different schemes. As a result, a time- and space-dependent temperature series for each of the collector components and the working fluid are obtained. To select an appropriate time and spatial steps for the developed model and to verify the reliability of the results received, the collector model is also implemented in ANSYS Fluent. The results of the one-dimensional model calculations and comparisons carried out in ANSYS demonstrate considerable agreement. In particular, the values of the fluid temperature at the collector outlet, calculated using the model developed, show high consistency with the ANSYS Fluent results. Furthermore, a preliminary experimental verification of the proposed model is carried out on a test stand currently under construction. The computed and measured temperature course of the fluid at the collector outlet is compared. In this case, the results are also satisfactory.

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“…由于电阻点焊熔核中心最后凝固的特性，点焊接头残余应力最大值往往在熔核内部。现有测量残余应力的方法多为表面应力测量，内部应力测试技术十分稀少，较为适合的中子衍射法设备昂贵成本高 [4] ，可利用率极低。用数值模拟的方法计算焊接残余应力可以节约时间，降低成本，近年来许多学者利用数值模拟技术对电阻点焊接头中的残余应力进行了研究 [5][6] 。AFSHARI 等 [7] 建立 6061 铝合金电阻点焊过程的二维轴对称有限元模型，研究点焊接头残余应力分布规律。MOSHAYEDI 等 [8] 通过有限元模拟分析焊接时间和焊接电流对 304 不锈钢点焊残余应力的影响，结果表明，提高焊接电流残余应力的最大值升高，而延长焊接时间对残余应力影响较小。采用有限元模拟研究异种铝合金电阻点焊接头残余应力还鲜有报导。有研究认为，焊接前后焊缝处材料力学性能变化对残余应力影响较大 [9][10][11] 。在异种铝合金电阻点焊过程中，熔核处材料的成分和热处理状态都可能发生变化，导致其力学性能与母材不同。因此，获得接头微区的力学性能是用有限元法准确预测异种铝合金电阻点焊接头残余应力的关键之一。然而，点焊熔核尺寸较小，难以制成拉伸试样测试熔核材料的力学性能，这为预测点焊接头中残余应力带来了困难。仪器化压入测试技术是近年来发展起来的一种材料微区力学性能测试技术 [12] ，这种技术的优点是可在小尺寸材料上进行测试，因此可借助该方 [7] 。模拟在有限元软件 Simufact Forming 中进行。点焊电极和待焊铝合金母材的力学性能和热物性参数见表 1、2 [13][14] [18][19][20] ，板厚组合通常较薄，可以忽略板厚方向 (Z 方向)的残余应力，而本研究中使用的板材厚度之和达到 10 mm，属于中厚板铝合金 [21]…”

Section: 点焊接头内部残余应力水平，对调节点焊工艺参数、预测接头服役性能具有指导意义。unclassified

Overall Residual Stresses in the Resistance Spot Welding Joint of Dissimilar Aluminum Alloys

Mao¹,

Kan²,

Jiang³

et al. 2020

Journal of Mechanical Engineering

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：A thermal-electric-mechanical coupling finite element model is established based on the instrumented indentation test and the finite element theory. The resistance spot welding (RSW) process of 5083 and 7N01 aluminum alloy is simulated. The distribution of the residual stress in the joint is obtained. The experiment of resistance spot welding is carried out. The morphology of the nugget, the distribution of hardness and residual stresses on upper and lower surfaces are obtained by using the metallographic microscope, the hardness tester and the sectioning relaxation stain-gage method, respectively. The influences of mechanical properties on values and distributions of the residual stress are discussed. The experimental results show that the nugget and the heat affected zone(HAZ) are softened after RSW. Compared with the 7N01 base metal, the hardness and flow stress of the nugget and the HAZ significantly decreased. The simulation results show that the influence of mechanical properties on the distribution of residual stresses is small. The mechanical properties mainly influence the values of the residual stresses. The residual stress in the nugget is a three dimensional stress of tension. The peak value of the residual stress appears at the center of the nugget. The predicted residual stresses from the developed finite element model agree well with experimental results.

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Investigation of the effect of sheet thickness on residual stresses in resistance spot welding of aluminum sheets

Cited by 24 publications

References 20 publications

Study on mechanical performance of laser-welded NiTinol sheet

Study on mechanical performance of laser-welded NiTinol sheet

Mathematical Model of a Sun-Tracked Parabolic Trough Collector and Its Verification

Overall Residual Stresses in the Resistance Spot Welding Joint of Dissimilar Aluminum Alloys

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