矩形截面弯管内流体流动特性分析及成形工艺研究

发布时间：2018-05-05 15:57

本文选题：矩形弯管 + 数值模拟　；参考：《山东建筑大学》2015年硕士论文

【摘要】：管道运输作为一种高效、廉价的运输系统,在国家生产建设过程中占据着重要地位,它广泛地应用于电力、冶金、化工、建筑、石油等工业领域。矩形截面弯管具有强度大、质量轻等优点,因此通常被用于输送流体介质,它可以在保证强度的同时节省一定的材料,在汽车工业领域有着非常广阔的应用前景。矩形管的弯曲成形方式主要有两种,种是在矩形管的宽面进行加工弯曲,称之为E弯；另一种是在矩形管的窄面进行加工弯曲,称之为H弯。在实际工程中,弯管在流体介质的作用下,易受到不均匀压力荷载作用而产生应力集中现象。本文针对流体作用下矩形截面弯管内壁面受力不均和弯管成形过程容易出现质量缺陷等问题,开展了相关研究。主要通过Fluent研究矩形截面弯管内流体流动的情况,以及采用ABAQUS建立矩形截面管弯曲成形的有限元模型,对矩形管材在不同弯曲程度时的应力及应变分布规律进行分析研究,得出了流体作用下弯管内壁面压力的分布规律并拟合出了矩形弯管内壁面凸凹边的压力公式以及管材弯曲成形过程中不同工艺参数变化对弯曲成形弯管件截面质量的影响规律。所得的研究结果对流体作用下弯管内壁面受力的准确分析以及成形过程中工艺参数的选取具有重要意义。为此,本文主要做了以下工作：(1)通过三维建模软件UG分别建立三种截面面积相等的矩形弯管(E弯、H弯、方形弯管),采用Fluent软件分析比较不同截面形式下的弯管内流体的流动状况和弯管内壁面的压力值,得出矩形截面弯管E弯是承受压力的最优情况。(2)采用Fluent对不同工况下E弯矩形管内壁面的压力值进行数值模拟,然后改变相关参数(流体入口流速、流体出口压力、弯管度、流体密度等),研究参数变化对弯管内壁面所受压力分布规律的影响。分析影响参数与压力差△P的关系,最终根据1stOpt拟合软件拟合出弯管凸凹边内壁面压力关于流体入口流速v、流体出口压力P0、弯管弯曲度k、弯管的轴向角度α和流体介质密度ρ变化的压力公式。(3)采用有限元分析软件ABAQUS,建立三维的矩形截面管材弯曲成形的有限元模型,通过仿真模拟得到管坯在不同弯曲程度时的应力及应变分布规律。深入分析了不同工艺参数变化对弯曲成形弯管件截面质量的影响,对于改进加工成形工艺、解释成形中缺陷的产生、控制弯管件的成形质量有着十分重要意义。
[Abstract]:As an efficient and cheap transportation system, pipeline transportation occupies an important position in the process of national production and construction. It is widely used in the fields of electric power, metallurgy, chemical industry, construction, petroleum and other industries. Rectangular section bends have the advantages of high strength and light mass, so they are usually used to transport fluid media, which can save some materials while ensuring strength, and have a very broad application prospect in automobile industry. There are two main bending methods of rectangular tube, one is machining bending on the wide surface of rectangular tube, which is called E bend, and the other is machining bending on the narrow surface of rectangular tube, which is called H bend. In practical engineering, the bending pipe is easy to be subjected to inhomogeneous pressure load under the action of fluid medium, which leads to stress concentration phenomenon. In order to solve the problems such as uneven force on the inner surface of rectangular section bend tube under the action of fluid and the easy appearance of mass defects in the forming process of the bend pipe, the relevant research has been carried out in this paper. The flow of fluid in rectangular bend tube is studied by Fluent, and the finite element model of rectangular section tube bending is established by ABAQUS. The distribution of stress and strain in rectangular tube with different bending degree is analyzed and studied. The distribution law of pressure on the inner wall of curved pipe under the action of fluid is obtained, and the pressure formula of the convex and concave edge on the inner wall of rectangular bend is fitted. The influence of different technological parameters on the cross section quality of bend tube in bending forming process of tube is also obtained. The results obtained are of great significance to the accurate analysis of the inner surface force of the curved pipe under the action of fluid and the selection of the technological parameters in the forming process. Therefore, the main work of this paper is as follows: 1) by using the 3D modeling software UG, three kinds of rectangular bend with equal cross-section area are established respectively. In this paper, the flow state of fluid and the pressure on the inner wall of the curved pipe are analyzed and compared by Fluent software. It is concluded that the E bend of rectangular section is the best case of bearing pressure. (2) numerical simulation of the pressure on the inner wall of the rectangular tube under different working conditions is carried out by using Fluent, and then the relevant parameters (fluid inlet velocity, fluid outlet pressure, bend degree) are changed. The influence of fluid density on the pressure distribution on the inner wall of curved pipe is studied. The relationship between influence parameters and pressure difference P is analyzed. Finally, according to the 1stOpt fitting software, the pressure on the inner wall of the convex and concave edge of the elbow is fitted with the pressure formula of fluid inlet velocity v, fluid outlet pressure P0, bend degree k, axial angle 伪 of the bend pipe and density 蟻 of the fluid medium. The finite element analysis software Abaqus is used to establish a three-dimensional finite element model of tube bending forming with rectangular section. The distribution of stress and strain of tube billet under different bending degree was obtained by simulation. The influence of different process parameters on the cross section quality of bending tube bending parts is deeply analyzed. It is of great significance to improve the forming process, explain the production of defects in the forming process and control the forming quality of the tube bending parts.
【学位授予单位】：山东建筑大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ055.81

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