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Fabrication of longitudinal welded tube of aluminum alloy for structural application using friction stir welding process and its characterization

Sen Debolina, Pal Surjya Kanta, Panda Sushanta Kumar

Archives of Civil and Mechanical Engineering

2022

Vol. 22, no. 2

art. no. e91, 1--21

Thin-walled aluminum alloy tubes used for structural applications can be produced by various processes among which friction stir welding process (FSW) has emerged rapidly due to its superior welded properties. But, FSW of tubular components is complex due to its curvature which makes it challenging to get the desired quality of the tube. Hence, in the present study, an attempt was made to fabricate longitudinal FSWed tubes of AA5083-O alloy. A novel parameter window highlighting their effects on the weld quality was presented, and the significant process parameters were optimized to get a defect-free good-quality welded tube. In this regard, X-ray micro-computed tomography, hardness and uniaxial tensile tests of the weld zone (WZ) were carried out to assess the weld quality. Negligible amount of porosity was observed in the WZ, and the hardness was comparable to that of the base material. The joint efficiency obtained was 87%, suggesting homogeneity of the WZ. To get further insight into the WZ homogeneity, the failure mechanism along with the microscopic damage initiation characteristic of the tensile samples was studied. Failure of these samples took place in between the nugget zone and the thermo-mechanically affected zone, and a mixed type of fracture was observed. Three types of void nucleation mechanisms viz., inclusion or particle cracking, interface debonding, and matrix cracking coexisted in the welded sample among which particle cracking was the most significant. Also, the surface roughness of the WZ was measured and it was observed that the material flow during the welding process affected the average roughness value.

Lateral impact of tubular structure – theoretical and experimental analysis. Part 1 – Investigation of single tube

Lipa S., Kotełko M.

Journal of Theoretical and Applied Mechanics

2013

Vol. 51 nr 4

873--882

If a thin-walled member is subjected to dynamic load, the estimation of its structural behaviour has to count for the strain-rate influence upon stress-strain material characteristics. It is particularly important when a thin-walled member works as an energy absorber. In the paper, the problem of collapse load, post-failure behaviour and energy dissipation of a tubular structure subjected to lateral impact load is presented. The analytical solution of the problem of initial collapse load and post-failure behaviour of a single tube is discussed. The analysis is limited to the “dynamic progressive crushing”, which means that we take into account the strain-rate but neglect inertia effects. The solution is based on the yield-line analysis and takes into account the impact velocity and strain rate, using the Cowper-Symonds constitutive relation. The same problem concerning both the single tube and multi-member tubular structure subjected to lateral bending impact load is solved using Finite Element (FE) simulation, which also takes into account the impact velocity and strain rate, using the corresponding to Cowper-Symonds Perzyna material model. Results of numerical calculations are compared with those obtained from the quasi-dynamic tests performed at different loading velocities on single tubes. The results are shown in load-deformation diagrams and diagrams of deformation patterns.