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Numerical Simulation of Friction Stir Spot Welding Process for Aluminum Alloys
김돈건,Harsha Badarinarayan,Ill Ryu,김지훈,김종민,Kazutaka Okamoto,R. H. Wagoner,정관수 대한금속·재료학회 2010 METALS AND MATERIALS International Vol.16 No.2
Thermo-mechanical simulations of the Friction Stir Spot Welding (FSSW) processes were performed for AA5083-H18 and AA6022-T4, utilizing commercial Finite Element Method (FEM) and Finite Volume Method (FVM)codes, which are based on Lagrangian and Eulerian formulations, respectively. The Lagrangian explicit dynamic FEM code, PAM-CRASH, and the Eulerian Computational Fluid Dynamics (CFD) FVM code, STAR-CD,were utilized to understand the effect of pin geometry on weld strength and material flow under the unsteady state condition. Using FVM code, material flow patterns near the tool boundary were analyzed to explain weld strength difference between welds by a cylindrical pin and welds by a triangular pin, whereas the frictional energy concept using the FEM code had a limited capacity to explain the weld strength difference.
Springback Evaluation of Friction Stir Welded TWB Automotive Sheets
Junehyung Kim,이원오,Kyung-Hwan Chung,김대용,Chongmin Kim,Kazutaka Okamoto,R. H. Wagoner,정관수 대한금속·재료학회 2011 METALS AND MATERIALS International Vol.17 No.1
Springback behavior of automotive friction stir welded TWB (tailor welded blank) sheets was experimentally investigated and the springback prediction capability of the constitutive law was numerically validated. Four automotive sheets, aluminum alloy 6111-T4, 5083-H18, 5083-O and dual-phase DP590 steel sheets, each having one or two different thicknesses, were considered. To represent mechanical properties, the modified Chaboche type combined isotropic-kinematic hardening law was utilized along with the non-quadratic orthogonal anisotropic yield function, Yld2000-2d, while the anisotropy of the weld zone was ignored for simplicity. For numerical simulations, mechanical properties previously characterized [1] were applied. For validation purposes, three springback tests including the unconstrained cylindrical bending, 2-D draw bending and OSU draw-bend tests were carried out. The numerical method performed reasonably well in analyzing all verification tests and it was confirmed that the springback of TWB as well as of base samples is significantly affected by the ratio of the yield stress with respect to Young’s modulus and thickness.
AA5083-H18판재의 마찰 교반 점 용접 공정에 대한 전산 해석
김돈건(Dongun Kim),Badarinarayan Harsha,유일(Ill Ryu),김지훈(Ji Hoon Kim),김종민(Chongmin Kim),Okamoto Kazutaka,Wagoner R. H.,정관수(Kwansoo Chung) 한국소성가공학회 2009 한국소성가공학회 학술대회 논문집 Vol.2009 No.5
Thermo-mechanical simulation of the Friction Stir Spot Welding (FSSW) processes was performed for the AA5083-H18 sheets, utilizing commercial Finite Element Method (FEM) and Finite Volume Method (FVM) which are based on Lagrangian and Eulerian formulations, respectively. The Lagrangian explicit dynamic FEM code, PAM-RASH, and the Eulerian Computational Fluid Dynamics (CFD) FVM code, STAR-CD, were utilize to understand the effect of pin geometry on weld strength and material flow under the unsteady state condition Using FVM code, material flow pattern near the tool boundary was analyzed to explain the weld strength difference between the weld by cylindrical pin and the weld by triangular pin, while the frictional energy concept using the FEM code had limitation to explain the weld strength difference.