等强度弯管壁厚公式设计及芯棒热推成形工艺优化

发布时间：2018-01-26 01:04

本文关键词： 弯管天然气压力模型壁厚公式热推工艺　出处：《山东建筑大学》2015年硕士论文　论文类型：学位论文

【摘要】：弯管在工业领域具有非常重要的用途,是石油、化工、航海、航空和核工业领域的重要零部件。当流体流经管道的弯管段时,会对弯管凸边形成较大冲击,在弯管凸边形成增压区、凹边一侧反而形成减压区,加之实际的管道输送网络大多需要在高温、高压的环境下运行,因此弯管往往成为管道的应力集中部位。由于加工工艺的限制,弯管加工成形时凸边管壁受拉减薄或开裂、凹边管壁受压增厚或起皱等问题,则成为导致弯管破坏的主要原因。因此,对弯管进行准确的受力分析便成为弯管壁厚设计的重要前提。本文利用FLUENT流体软件对天然气流经弯管的流动特性进行了数值模拟,分析了各参数对弯管内壁面压强的影响规律,并给出了90°弯管内压三维分布模型。通过对弯管进行受力分析,分别求出了轴向应力、环向应力、径向应力三个主应力及变壁厚等强度弯管壁厚设计公式。借助于有限元模拟软件ABAQUS对牛角芯棒热推成形工艺进行模拟分析,并比较了不同的工艺参数对弯管壁厚的影响,得出了热推弯管成形工艺的最佳工艺参数。具体研究内容如下：(1)应用计算流体力学软件FLUENT对天然气在90°弯管内的流动特性进行仿真模拟,并分析了弯管内壁面压强的分布规律。(2)改变天然气的流动参数、弯管几何参数,在48种工况下对天然气在弯管内的流动进行模拟,建立弯管内压的数据库,并分析了不同参数的变化对弯管内压的影响。(3)应用弯管内压数据库,借助于数学拟合软件1 stOpt建立弯管内壁面压强的三维模型。结合弯管内压模型对弯管的应力状态求解,利用第三强度理论得出变壁厚等强度弯管的壁厚设计公式。(4)应用有限元软件ABAQUS模拟了牛角芯棒热推成形工艺,通过分析不同工艺参数对壁厚分布的影响,实现了对工艺参数速度v、温度T、摩擦系数f的优化,得出了最佳的工艺参数。
[Abstract]:Bends are very important parts in the fields of petroleum, chemical industry, navigation, aviation and nuclear industry. When the fluid flows through the pipe section of the pipe, it will form a great impact on the convex edge of the bend pipe. A pressurized zone is formed at the convex edge of a curved pipe and a decompression zone is formed on the concave side. In addition, most of the actual pipeline transportation networks need to operate under high temperature and high pressure. Because of the limitation of the processing technology, the bulge tube wall is thinned or cracked, and the concave pipe wall is compressed and thickened or wrinkled due to the limitation of the processing technology. It becomes the main cause of the failure of the elbow. The accurate force analysis of the bend pipe becomes an important prerequisite for the design of the wall thickness of the bend pipe. In this paper, the flow characteristics of natural gas flowing through the bend pipe are numerically simulated by using the FLUENT fluid software. The influence of various parameters on the pressure on the inner wall of the curved pipe is analyzed, and a three-dimensional distribution model of the internal pressure of the 90 掳bend is given. The axial stress and the circumferential stress are obtained by the analysis of the force on the elbow. The design formula of radial stress for three principal stresses and variable wall thickness for curved tubes with equal strength is presented. The hot push forming process of corrugated corrugated corrugated bars is simulated and analyzed by means of finite element simulation software ABAQUS. The influence of different process parameters on the wall thickness of the curved pipe is compared. The optimum technological parameters of the hot push tube forming process are obtained. The specific research contents are as follows: 1) the flow characteristics of natural gas in 90 掳bend pipe are simulated by the computational fluid dynamics software FLUENT. The distribution law of pressure on the inner wall of curved pipe is analyzed. (2) changing the flow parameters of natural gas and geometric parameters of the bend pipe, the flow of natural gas in the bend pipe is simulated under 48 working conditions. The database of internal pressure of bend pipe is established, and the influence of different parameters on internal pressure of bend pipe is analyzed. With the help of the mathematical fitting software 1 stOpt, the three-dimensional model of the pressure on the inner wall of the bend pipe is established, and the stress state of the bend pipe is solved by combining the internal pressure model of the bend pipe. According to the third strength theory, the design formula of the wall thickness of the curved pipe with variable wall thickness is obtained. (4) the hot-push forming process of the corrugated corrugated rod is simulated by using the finite element software ABAQUS. By analyzing the influence of different process parameters on the distribution of wall thickness, the optimum process parameters, such as velocity v, temperature T and friction coefficient f, are obtained.
【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】：TE973

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