Analysis And Amplitude Detection Of Pipe Bending Vibration

As an important role-player,pipelines are widely used in many fields such as water conservancy,liquid transportation,and chemical engineering,and have become indispensable engineering structures.For example,competition for resources in space,energy use for the seabed,technical control of nuclear energy,distribution and transportation of water resources and petroleum resources,etc.At the same time,it also exists in the civil fields that are closely related to our lives,including urban water supply and drainage pipelines and natural gas supply pipelines.There is no doubt that the pipeline plays an important role in it and has a heavy responsibility.However,due to the long-term effects of various environmental loads or when subjected to dynamic loads,different types and degrees of cracks,or even damages,will inevitably occur in welding defects or geometric stress concentrations.If they are allowed to develop,the system itself will suffer from a decrease in resistance and a decrease in its service life.Severely,it will suddenly break.Visible,research and analysis of the piping system by the resonance vibration characteristics and fatigue test,And measuring changes in the amplitude of the pipeline,its meaning is quite far-reaching,practical engineering production,its value is also difficult to measure.This paper aims at the theory analysis of the vibration of the pipeline system and the measurement method of the pipe bending amplitude,and systematically conducts theoretical and experimental researches.The main contents of the paper include:1.A simple mechanical model of a free-floating tube was established for the bending vibration of the pipe.The mechanical model was used to calculate and analyze the vibration frequency and vibration mode of the pipe with the mass at both ends,which provided theoretical basis for the construction of the later experimental device.2.Study the distribution of force in pipelines and explore the variation of the bending vibration of pipelines.Determine the measurement position of the amplitudefor its changing law and make corresponding measurement marks on the pipeline.And in order to determine the vibration video camera shooting angle of the pipe.3.Take a video of the vibration process of the pipeline through the camera and process it into a frame of image with the aid of computer software.Analyze and compare the pixel coordinate values at the pipeline markings to select the image of the pipeline.The pre-analysis of the pipeline image is aimed at reducing the computational load of the computer,improving the processing efficiency,and at the same time ensuring the accuracy of the pipeline edge detection at the later stage.4.Study the measurement method of pipe bending amplitude based on edge detection.Compare and analyze several different edge detection algorithms,select an algorithm that detects the edge of the pipeline,and draw the curve of the upper edge of the pipeline.Thus,the degree of bending of the pipe during the vibration process can be seen,and the bending amplitude of the pipe during vibration can be calculated.5.By studying the vibration test of the pipeline under different conditions,Specifically,the test data obtained based on the edge detection method was analyzed.And compare it with the data measured by the dial indicator.The feasibility of the measurement method based on edge detection was verified.