| Ultrasonic guided wave detection technology is a very promising detection technology that can achieve non-destructive testing of pipeline defects and pressure.However,when the pressure detection of hydraulic pipelines is based on ultrasonic guided wave technology,it is often interfered by environmental factors such as pressure,resulting in low detection accuracy.In order to study the influence of temperature and pressure on the propagation characteristics of ultrasonic guided waves and improve the detection accuracy of pipeline pressure,this paper analyzes the propagation characteristics of ultrasonic guided waves in hydraulic pipelines by theoretical analysis,numerical calculation and experimental study on the propagation characteristics of ultrasonic guided waves.Influencing factors.The finite element software ABAQUS is used to simulate the propagation characteristics of ultrasonic guided waves in empty pipelines and liquid filled tubes.The research results are as follows:1.Experimental study and analysis of the propagation characteristics of ultrasonic guided waves in a changing environment were carried out using experimental equipment.The effect of pressure on guided wave propagation is mainly reflected in the direct peak-to-peak variation.The results show that with the increase of liquid pressure,the peak-to-peak value and RMS value of the guided wave direct wave decrease linearly.When using the peak-to-peak value to study the influence of the change of pressure on the propagation characteristics of ultrasonic guided waves,the L-modal test results are more obvious than the T-mode,which is easier to analyze.The magnetostrictive sensor can be used to excite L.Modal guided wave signal.When the RMS value is used to study the influence of the pressure change on the propagation characteristics of the ultrasonic guided wave,the T-mode guided wave signal can be excited by the torsional modal sensor because the T-mode test result is more obvious than the L mode.In this way,the influence of the change of pressure on the propagation characteristics of the guided wave can be obtained by different research methods,and the accuracy of the pressure detection can be improved.2.Changes in temperature cause changes in the properties of the sample material itself,which in turn affects the propagation characteristics of the ultrasonic guided waves in the structure.When peak-to-peak and RMS values are used to study the effect of temperature changes on the propagation characteristics of ultrasonic guided waves,it is found that the peak-to-peak and RMS values of the direct wave signal decrease with increasing temperature,and the magnetostrictive sensor excitation The L mode guided wave signal is reduced by a larger amplitude than the T mode guided wave signal excited by the torsional mode sensor.The method of exciting L mode guided wave can be used to study the influence of temperature change on the guided wave propagation characteristics,which can eliminate the influence of temperature change on the guided wave propagation characteristics and improve the accuracy of pressure detection.3.The propagation characteristics of the guided wave in the empty tube and the liquid filled tube are studied by experimental research and numerical simulation.The experimental results are consistent with the simulation results.When the guided wave propagates in the liquid-filled pipeline,energy loss occurs,resulting in a decrease in the amplitude of the echo signal.At the same temperature,the peak-to-peak value of the liquid-filled tube signal is smaller than the peak-to-peak value of the empty tube;as the temperature increases,the peak-to-peak value of the guided wave directly decreases.For every 5? increase in temperature,the peak peak of the ultrasonic guided wave in the empty tube or tubing is reduced by 0.001 mV.By analyzing the propagation characteristics of guided waves,it is possible to better identify and eliminate the influence of various environmental factors on guided wave propagation,and provide data reference for the application of subsequent ultrasonic guided waves. |
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