Stress Acquisition Method And Life Prediction Theory Of Pipe Based On Vibration Measurement

Real-time in-service pipeline stress detection and analysis is an effective method to protect the safe operation of the pipeline,This research supported by the National Natural Science Foundation of China General project(No.51175466)named Extraction and Recognition of Weak Impact Signal and the National Basic Research Program of China(973 Program,No.2011CB706505)named Key Scientific Problems of Super Large-sized and Low Energy Consumption Development of Complex Air Separation Equipment carried out a real-time stress obtaining model based on vibration measurement and develop a pipeline safety inspection and life prediction system,The main contents of the dissertation are as follows:In the first chapter,the research background,analysis pipeline failure mode and the research status of pipeline safety assessment and life prediction theory is presented in this paper,proposed content and framework of the study.In the second chapter,by analyzing the relationship between stress and bending moment,the moment and the radius of curvature Build mapping model of stress and the second derivative of vibration amplitude.Optimize model by setting the equidistant sampling interval of each sensor.Pick out the directly mapping model between stress and amplitude by combining with large deflection properties of long pipeline.In the third chapter,simulation analysis has been made based on ANSYS and MATLAB to certify the reliability and universality of vibration stress model by comparing the model stress result with the finite analysis stress result in the different boundary conditions,different sampling intervals,different vibration modes,different ratio of diameter and length,and different pipe styles.At the same time,proposed the layout of the sensors.In the fourth chapter,a method of life prediction has been proposed based on the vibration stress model result.All stress cycles of different stress amplitude and mean stress conditions by using new rain-flow counting theory has been picked up.Combine the fatigue S-N curve and Miner theory to predict the pipe life.In the fifth chapter,Real-time in-service pipeline stress detection and life prediction system has been developed.Build the experimental platform to carry out the pipe vibration test in different boundary conditions.Collect the vibration signals an stress signals and compare the vibration stress model result with the strain gauges result to verify the reliability of the model and system.In the sixth chapter,the further research is putted forward after summarizing all the achievements of dissertation.