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Deformation and Damage Behaviour of 6063 Aluminum Alloy T-welded Joints

Author: XuWenFu
Tutor: ChenJianHong；ZhuLiang
School: Lanzhou University of Technology
Course: Materials Processing Engineering
Keywords: Aluminum alloy T- welded joints Material Characterization Stress state Damage Finite Element Simulation
CLC: TG407
Type: Master's thesis
Year: 2009
Downloads: 236
Quote: 1
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Abstract

The lightweight aluminum alloy car body is the development direction of the energy-saving environmentally friendly vehicles, the development of new materials of aluminum alloy, aluminum alloy material, weldability, and analysis of the mechanical properties of the aluminum alloy welded joints and the change in the law is a hot research topic. The fillet weld is one form of the main connection of the welded structure, consisting of T-shaped welded joints by the fillet weld at the connection of the aluminum body frame structure has been widely used, but the organization, the performance and the complexity of the stress state influence the performance of the entire body frame structure. Around the problem by mechanical testing and micro fracture observation combined with the finite element simulation method, the study of the deformation and damage behavior of 6063 aluminum alloy single-sided fillet weld T-joint: First of all, taking into account the extrusion material anisotropic effects of the 6063 aluminum alloy extrusion direction at different angles on the direction of material mechanical properties characterized, the results show that: the direction of extrusion of aluminum alloy material anisotropy smaller sampling as a follow-up test way and finite element simulation to provide the necessary theoretical basis. Tensile and shear tests on aluminum alloy base metal mechanical properties characterization. The macroscopic test results show that: break strain is greater than the time of plate tension notched tensile fracture strain, and Tablet tensile yield the notched tensile stress is less than the yield stress, shear fracture of the material in the shearing strain far outweigh Tablet tensile fracture strain. Fracture observation: With the three-way should be efforts to increase the dimple fracture mechanism increases the shear fracture mechanism decreases. The tensile fracture dimple main shear fracture in a large shear dimples and shear plane. Finite element simulation, the choice of the damage model to consider a three-way should be the strength of the impact. In addition, the damage simulation parameters are sensitive to the grid size. Second aluminum alloy T-joint local mechanical properties were characterized by two-hole micro-shear test. TIG welding prepared to test the T-joint aluminum alloy, there is a big difference between the joints of the microstructure and mechanical properties of the various micro using metallographic test and two-hole micro-shearing method T-joint vertical plate and bottom plate of the micro- the width of the measured material properties were characterized, and the results showed that: two holes micro-shearing device better determination of the local mechanical properties of the T-joint value of 1.07%, the maximum error of the repeatability of test results, and sample preparation higher test accuracy; using the finite element inverse method and test the combination of connector micro mechanical performance parameters and Johnson-cook damage model parameters, modeling for finite element simulation of the T-joint mechanical testing basis. Finally, T-joint design 3D solid modeling software Solidworks different angles tensile test specimens and fixtures, and tensile test and fracture observation results show that: in addition to the 0 degree tensile curve, the other four curves in the plastic deformation process a \T-joint tensile fracture observation that: sample macroscopic fracture occurs mainly in the softening of the T-joint vertical plate area, but due to the inhomogeneity of the mechanical properties of the micro-fracture exists significant difference. T-welded joints at 0 degrees, 30 degrees, the experienced stretch - bend - the process of breaking stretch of 45 degrees and 60 degrees, the fracture by brittle fracture facets and dimples. Which, in 60 degrees of tension are formed due to bending tear, dimple fracture, there is a lot of tearing. T-welded joints in 90 degrees of tension, not experience bending process, in addition to a small fraction of brittle fracture facet fracture mainly distributed in a large number of dimples, is a normal fault type fracture. GTN damage model of the T-joint damage behavior under different stress states finite element simulation analysis, the results show that: the simulation and experimental curves fit better, the T-joint damage evolution and failure behavior is consistent with the experimental results, GTN injury model can simulate the damage behavior of the T-joint under different stress states; fracture strain increases with the the weld relative width increase, the maximum equivalent plastic strain from the base metal and the heat affected zone. side of the steering weld on one side, but the void volume fraction VVF essentially unchanged. T-joint test and FEM simulation later vehicle collision simulation analysis of actual practical value, but to get a more accurate simulation results, the need to achieve continuous material properties of welded joints, from welding simulation analysis , welding simulation analysis of data as a simulation of the mechanical properties of the premise, the establishment of post-weld material model.

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CLC: > Industrial Technology > Metallurgy and Metal Craft > Welding, metal cutting and metal bonding > Welding general issues > Mechanical properties of welded joints and Intensity
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