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1

Influence of adhesive on dynamic performance of steel/Al electromagnetic clinched joints

Liao Yuxuan, Zhong Jiabao, Li Guangyao, Cui Junjia, Jiang Hao

Archives of Civil and Mechanical Engineering

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2022

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Vol. 22, no. 4

art. no. e177, 2022

EN

In this paper, the dynamic behavior of clinched, bonded and clinch-bonded joints for steel/Al was investigated. Three tensile speeds (1 m/s, 5 m/s, and 10 m/s) were selected. The strain evolution of three kinds of joints was analyzed by the digital image correlation (DIC) technique. The mechanical properties and failure mechanism of joints were obtained. The result showed that the shear strength and energy absorption of joints were both increased as the tensile speed increased. When the tensile speed increased from 1 to 10 m/s, the peak loads of clinched joints, bonded joints and clinch-bonded joints were increased by 26.7%, 17.5% and 16.3%, respectively. The energy absorption of three kinds of joints were increased by 35.4%, 27.3%, and 29.0%, respectively. Besides, the addition of adhesive effectively improved the shear strength and energy absorption of the joint compared to clinched joints. Specifically, the peak load and energy absorption were increased by nearly three times and thirteen times, respectively. The failure modes of clinched joint ranged from mixed failure to neck failure. While the failure modes of bonded joint were mixed failure at different tensile speeds. For clinch-bonded joint, the failure modes of interlock structure were the neck failure and the failure modes of adhesive layer were mixed failure. With the increase of the tensile speed, the cohesive failure area of bonded joint and clinch-bonded joint decreased, and the damage degree of mechanical interlock was more serious for clinched joint.

2

Mechanical properties and corrosion behavior of galvanized steel/Al dissimilar joints

Jiang Hao, Liao Yuxuan, Jing Lijun, Gao Song, Li Guangyao, Cui Junjia

Archives of Civil and Mechanical Engineering

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2021

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Vol. 21, no. 4

555--567

EN

In this paper, the mechanical properties and corrosion behavior of steel/Al electromagnetic self-pieced riveting, adhesive and hybrid riveted and adhesive joints in the salt-spray environment were compared. These joints were firstly placed in the neutral salt spray environment, and then surface observation, weighting, mechanical properties tests and fractographic analysis were conducted. Results showed that with the increase of ageing time, the peak load of the single riveted joints firstly increased and then decreased, while the peak loads of the other two joints continued to decline. This was because the corrosion products formed in the sheet clearance of the single riveted joint, increasing the frictional resistance during the shear process after a short ageing time (before 20 days). For adhesive and hybrid joints, adhesives prevented the formation of corrosion products in the clearance, but it was vulnerable to damage by chloride ions, which would result in the continuous strength degradation of the joints. Specifically, after ageing for a long time (25 days), the peak load of the riveting, adhesive and hybrid joints, respectively, decreased by 11.2%, 26.3% and 14.4% comparing with the uncorroded joint, which showed the adhesive joint had the worst corrosion resistance. This indicated that the adhesive joint was more affected by environmental factors than the riveted and hybrid joint.

3

Influence of electromagnetic riveting process on microstructures and mechanical properties of 2A10 and 6082 Al riveted structures

Dong Dongying, Sun Liqiang, Wang Qiong, Li Guangyao, Cui Junjia

Archives of Civil and Mechanical Engineering

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2019

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Vol. 19, no. 4

1284--1294

EN

Electromagnetic riveting (EMR) technology had unique connection advantages compared to traditional riveting methods. The influence of EMR process on microstructures and mechani- cal properties for 2A10 and 6082 aluminum riveted structures was investigated by comparison with regular pressure riveting (RPR) process. The microstructures and mechanical properties of the two riveting processes were analyzed by optical microscopy and tensile testing machine, respectively. The micro-hardness and the interference amount were also investi- gated. The results showed that the main characteristic of the driven head was the shear zone. The grain deformation of the EMR in shear zone was more severe than that of the RPR. The width of the shear zone of the RPR was larger than that of the EMR. The trend of micro- hardness distribution was opposite along the direction of the shear zone. Meanwhile, the distribution of the interference amounts of EMR had a better uniformity. The failure mecha- nisms of shear tests of the EMR and RPR were same, but the pull-out tests were different. The dynamic loading had a great influence on the microstructures and mechanical properties of riveted structures, and the mechanical properties of EMR were significantly enhanced.

4

Numerical simulation and experimental investigations on TA1 titanium alloy rivet in electromagnetic riveting

Zhang X., Zhang M., Sun L., Li C.

Archives of Civil and Mechanical Engineering

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2018

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Vol. 18, no. 3

887--901

EN

In this work, an electromagnetic-mechanical-thermal coupling numerical model was proposed and electromagnetic riveting (EMR) experiments were performed using Φ6 mm TA1 titanium alloy rivets. Experimental verification showed that the proposed model could be suitable for predicting the EMR process, and the corresponding relationships among magnetic pressures, deformations of rivet tails and discharge voltages were revealed. In addition, simulation results presented that most deformations occurred in the locally upsetting stage of rivet tail. The maximum temperature rise reached up to 426 °C within the shear deformation zone of rivet tail. The rivet tails with high speed deformations could bear 9.9 kN shear loads and 12.5 kN pull-out loads, respectively. The EMR joining structures with multi-layered sheets had very high interference-fit qualities, and the average relative interferences were 2.5–3.0% for as-received multi-layered structures. Consequently, the EMR process can be used for difficult-to-deformation material rivets under the high efficiency, high quality and ambient temperature.