| The high quality aluminum rectangular tube is widely used to convey microwave signal in the fields of radar, navigation, aviation and telecommunication. There is a high level requirement for dimensional accuracy of aluminum rectangular tube, especially for the inner surface quality which is critical for the attrition rate of microwave signal. At present, the aluminum rectangular tube with high accuracy of dimension can be manufactured after solving several defects including dimensional deviation, wall unevenness, indent of center of long side and fracture by Chongqing university. However, the inner surface quality is still out of operating requirement, so the further research and analysis is necessary. The article analyses the effect of several initial material parameter and working conditions on surface roughening, such as initial grain size, texture types, loading and sliding speed. The main research contents were as follows:① The polycrystal finite element model is established through voronoi polyhedrons, and the optimum model size can be obtained on the base of statistical calculation, through which the computational efficiency can be improved and material information is incorporated enough. Therefore, it is convenient for following finite element analysis.② The effect of different grain size on surface roughness evolution under several strain routes is researched. The result shows that the regularity that surface roughness can reduce with grain size decreasing can be found in all five strain routes. It can explained that strain difference between neighboring grains can be reduced with smaller grain size, leading to a more uniform deformation. Thus, refining grain is a valid method to reduce the deformed surface roughness.③ The effect of texture types on surface roughening is studied. It turns out that the surface roughness caused by S texture is largest, while cube and Goss textures can lead to a smaller surface roughness, which may be related to Taylor factor. In addition, S texture is sensitive to deformation condition, but cube texture is relatively stable. Therefore, S texture should be avoided in manufacturing process with complicated loading and deforming conditions.④ On the base of 3D finite element model combined with surface topography, the effect of contact pressure and sliding speed on surface roughness evolution is analyzed. The results indicate that surface roughness shows a decreasing tendency with contact pressure increasing, which results from the flatting of mould. When sliding speed ranges from 16mm/s to 64mm/s, surface roughness increases first and then decreases with sliding speed increasing.⑤ The Al6061 uniaxial tension experiments are carried out through two tensile samples with different grain size and grain orientation. The results between experiment and simulation are in great agreement, which verifies the conclusions of simulations and also demonstrates the finite element model based on crystal plasticity theory is reliable.⑥ The grinding experiment is conducted to research the effect of loading and sliding speed. The results of experiment and simulations are not coincident because of the lack of wear mechanism and lubricating property during finite element analyzing. As a consequence, wearing and lubricating should be incorporated into finite element analysis, which gives a specific direction for simulation in the future. Besides, the friction coefficient can reach the minimum under heavy load and high speed.On the background of high quality aluminum rectangular tube, the effect of several material parameters and working conditions on surface roughening is researched through crystal plasticity theory under simple strain routes, which gives a certain theoretical reference for solving the inner surface roughness problem in the future. |
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