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Three Dimensional Numerical Simulation Of Temperature And Stress Distribution In Electron Beam Welding Of 12mm TC4 Titanium Alloy Plate

Posted on:2006-01-09Degree:MasterType:Thesis
Country:ChinaCandidate:M J HuFull Text:PDF
GTID:2121360152482384Subject:Materials Processing Engineering
Abstract/Summary:PDF Full Text Request
Many advantages of titanium alloy meet the requests of aviation, space navigation and atomic pile to metal material, for example high specific strength, good corrosion resistant, high melting point and excellent performance at elevated temperature. Electron beam welding is one of the best methods employed in the welding of titanium alloy because of high energy density, small heat-affected zone, and low pollution etc.Heat input of electron beam welding mainly focuses on welding bead. So there is rapid temperature change in the zone of welding and high temperature gradient in the inner of work piece, which are reasons for residual stress generation. The existence of residual stress is the important element for structural strength and service performance. It has very important meaning for engineering practice to analysis temperature and stress developing process in electron beam welding and to research formation mechanics of residual stress.Under high performance cluster computer system of NWPU, finite element model for analyzing temperature field of electron beam welding is set up based on ANSYS software code, 12mm TC4 titanium alloy as the research object. Cone body heat source model is proposed in temperature field simulation according to the characters of electron beam deep welding. Simulation of molten pool shape and trim welding line are well consistent to references, which validate the applicability of the cone body heat source model in electron beam deep welding. Based on thermal elastic-plasticity theory, finite element model for stress field of electron beam welding is set up and then employed to compute the development histories of thermal elastoplastic stress during welding process and distribution of residual stress after welding. High residual stress distribution zone lies in the center of work piece. There has residual stress value between 300MPa and 594MPa in the 10mm zone from welding line. Vertical stress mainly is compression stress in depth, the highest value lies in the center of work piece.Focusing spot diameter of vacuum electron beam welding is between 0.1mmand lmm. To describe exactly the distribution character of electron beam deep welding heat source, it is necessary to refine mesh around the weld bead compare to common welding method, which leads to large computing costs. Parallel computation of welding process numerical simulation is implemented under cluster computer system. The results show that compute time is reduced greatly on the premise of computation precision. It has important applicable for large-scale complex welding assembly.
Keywords/Search Tags:titanium alloy, electron beam welding, numerical simulation, temperature field, stress field, residual stress
PDF Full Text Request
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