Analysis And Optimization Of Welding Deformation Of TA15 Titanium Alloy Structure

Laser welding is a major joining process used in every manufacturing industry.Industries like automotive,aerospace and shipbuilding rely heavily on laser welding because of its efficiency,economy and dependability as a metal joining method However,welding can introduce significant distortion in the final welded geometry.which causes loss of dimensional control,costly rework and production delays.In automotive industry,it is a common practice today to use thin-sectioned.high-strength sheet metals to achieve weight reduction of body structure.But the structures made of relatively thin components are the most vulnerable to distortion when subjected to welding.Despite tremendous development in welding technology over the years,weld induced distortion is still one of the major obstacles for cost-effective fabrication of lightweight structures.Distortion in welded structures is largely influenced by the design parameters of the welding process,better control of these welding variables will eliminate the conditions that promote distortion.However,since welding is a multi-variables dependent process,it is often difficult or impossible to achieve the optimum set of these factors by traditional trial-and-error-based experimental methods.With the support of computer technology,FEM is still the most popular and powerful tool used in simulating the thermomechanical behavior of a structure during welding.The research object of this paper is the skin skeleton structure of TA15 titanium alloy material.It is researched on how to reduce the welding residual stress and deformation.The welding special software simufact.welding is used to conduct numerical analysis of the welding deformation of the structure.The main research contents of this thesis are as follows:(1)Research the optimal welding process of the TA15 titanium alloy skin skeleton structure sample,and compare the weld morphology and defects through the metallographic photos of the weld seam of different welding process tests,and obtain the expected welding process,and Test the tensile properties of the sample.(2)According to the keyhole forming characteristics of laser deep penetration welding,through repeated comparison of simulation and test results,a suitable heat source model is selected,and the heat source shape parameters are adjusted to obtain a simulated molten pool morphology that fits the metallographically of the test weld;Through temperature field simulation and thermal cycle curve verification,the laser parameters suitable for simulation are obtained.(3)Carry out numerical simulation of welding stress and strain field of skin skeleton structural parts,analyze welding deformation and residual stress of overall structural parts;and discuss the influence of welding sequence and tooling constraints on welding deformation and residual stress;further to control post-weld deformation,Design a flexible chemical fixture,and test the effect of the fixture on welding deformation through welding simulation.