Research On Calculation Method Of Pipeline Bending Stress Based On Inertial Navigation

In recent years,with the rapid development of industrialization,the scale and number of oil pipeline projects are increasing.In the long time transportation process,due to the influence of the weight of the pipeline,environmental temperature,geological disasters and other factors,the pipeline will be bending deformation to a certain extent,resulting in bending stress.Safety problems such as fatigue and crack caused by excessive bending stress affect the safety and economic benefits of pipeline oil and gas transportation.The stress distribution in pipe bend has become one of the key problems in engineering design and safety evaluation.Traditional pipe bending stress detection methods mainly rely on strain gauge,sensor and other equipment for real-time monitoring,but due to the measurement accuracy,equipment cost,installation and maintenance problems,limited its popularity in practical applications.To solve this problem,this thesis studies the calculation method of pipeline bending stress detection based on inertial navigation technology,and verifies its accuracy and effectiveness through experiments.In order to calculate the bending stress of pipeline,the mechanical properties of pipeline materials and inertial navigation mapping technology are studied.The center line information of the pipeline was accurately measured by inertial measurement unit,and the strain state was calculated by the curvature of the center line with the cross section of the pipeline as the reference plane.Finally,the bending stress of the pipeline was calculated by combining the elastic modulus of the pipeline material.Firstly,according to the particularity of the internal environment of the pipeline,a preprocessor is designed to filter the collected data and noise information that cannot represent the movement information of the detector.Based on the error models of mileage wheel and strapdown inertial navigation system,quaternion attitude update method and extended Kalman filter data fusion algorithm were used to integrate the output speed information of mileage device with the strapdown inertial navigation information,and solve the scale drift problem of gyroscope accelerometer in long time navigation.In this thesis,the difference between the mileage wheel displacement increment and the strapdown inertial navigation displacement increment is selected as the observed value.The pipeline bending stress calculation system developed by Matlab software is combined with navigation data and check point information to obtain the attitude information and position information of the detector in the pipeline,and then accurately describe the trajectory of the pipeline center line and the bending stress of the pipeline.The experimental and data calculation results show that the carrier’s attitude and motion information can be obtained by using the mileage wheel/inertial navigation data fusion algorithm,and the calculated trajectory can describe the actual experimental running state.Several push-pull experiments and data calculation were carried out for different settlement values of the pipeline,and the bending strain obtained by the calculation was compared with the measured value of the strain gauge.The calculation error met the engineering requirements.Finally,subsection calculation is carried out to the engineering practice data to predict the bending stress of pipeline.The research results can provide reference for pipeline operation safety.