低真空管道结构温度应力模拟实验研究

Model Experimental Research on the Temperature Stress of Low Vacuum Pipeline Structure

研究目的:磁悬浮列车的高速运行会引起低真空管道温度升高,使得温度应力成为一项不可忽视的结构荷载,因此有必要开展结构温度应力试验,判断结构运用的可行性,同时如何基于体积小巧的电阻应变片进行温度应力的解析方法也亟待研究。基于此,本文设计和搭建可模拟低真空环境的管道结构实验平台开展实验研究,并以电阻应变片为温度应变测试元件,探讨基于应变片直接观测数据的温度应力解析方法。研究结论:(1)温度荷载作用时,被测结构的实际变形量、应变片热膨胀系数和电阻温度系数共同决定了电阻应变片实测读数;(2)低真空管道内壁温度高于50℃后,外壁圆周方向的约束出现了强弱交替变化的现象,低真空管道内壁温度达到60℃时温度拉应力达到5 MPa左右,需要引起重视;(3)推导的应变修正公式和应力计算公式可为基于应变片观测数据的温度应力分析提供依据:(4)本文实验研究结果可为低真空管道运输系统的结构选型及温度控制提供参考。

Research purposes:The high speed operation of maglev train can cause temperature increment of low vacuum pipe,which makes the temperature stress become an assignable structure load.So it is necessary to carry out experiment about structure temperature stress to determine the feasibility of the structure.At the same time,the temperature stress analysis method also needs to be studied based on the small size resistance strain gauge.In this paper,the test platform of low vacuum model pipeline structure was set up for the experimental study,and the temperature stress analysis method was discussed based on the data directly observed by resistance strain gauge.Research conclusions:(1)The actual deformation of measured structure,thermal expansion coefficient and temperature coefficient of resistance strain gauge codetermine the resistance strain gauge reading under temperature load.(2)When the temperature of pipe inner wall is above 50℃,the constraining force around the outer wall circumference are in strong-weak cycles.When the inner wall temperature reaches 60℃,the temperature tensile stress reaches about 5 MPa,which needs to be pay more attention to.(3)The strain correction formula and the stress calculation formula can provide the basis for the temperature stress analysis based on the strain gauge observation data.(4)The experimental results can provide reference for pipe selection and temperature control of low vacuum pipeline transportation system.