Research And Design Of Ultrasonic Guided Wave Pipeline Defect Detection System Based On OneNET And LabVIEW

Pipeline transportation plays an important role in economic development and national defense industry.In practice,major safety accidents are caused due to the lack of comprehensive detection of pipeline defects.Therefore,it is necessary to adopt an efficient,accurate and convenient nondestructive testing technology for pipelines to effectively reduce pipeline safety risks.Compared with traditional detection methods,ultrasonic guided wave detection technology has unique technical advantages.Based on the theory of ultrasonic guided wave detection,this paper studies and designs a set of ultrasonic guided wave pipeline defect detection system,which consists of detection terminal,data transmission cloud platform and Lab VIEW client.The main research contents are as follows:(1)The detection signal of the system is studied in this paper.The guided wave model and defect detection principle of the pipeline were studied theoretically,and the transmission characteristics of the guided wave in the pipeline were simulated.The L(0,2)mode of 50-180 k Hz frequency band was selected from the dispersion curve simulation results,and the optimized signal was modulated by narrowband excitation mode to achieve the effect of enhancing the main lobe of the excitation signal and suppressing the side lobe.Simulation results show that the axial defect resolution performance of the modulated signal is enhanced and the excitation signal parameters are determined.The non-stationary signal processing algorithm of the acquisition signal is studied,and the optimized wavelet global soft threshold filtering algorithm is used to achieve significant noise reduction effect of the acquisition signal.Based on the theoretical research and the actual pipeline testing requirements,the testing technical indicators are formulated,and the hardware and software design scheme of the system is described in detail.(2)Hardware selection according to the hardware design scheme.Multichannel signal excitation circuit,multi-channel signal acquisition circuit,control logic circuit and other core circuits are designed.In order to meet the requirements of symmetrical guided wave modal excitation and arbitrary quadrants flaw detection of the pipeline,the signal excitation and acquisition circuit can work in parallel or separately,and the corresponding control logic circuit is designed so that 8 pieces of waveform excitation and waveform acquisition memory can store or write data in parallel or separately.The frequency adjustable square wave generator is designed to realize different excitation frequencies and sampling frequencies,and the signal acquisition gain is adjustable by using the programmable amplifier.The wireless module is used to connect the detection terminal to the data transmission cloud platform.(3)The software design is divided into three parts according to the software design scheme.Relying on the One NET platform and EDP Io T protocol,a cloud platform for two-way real-time data transmission between the detection terminal and the client is built.Modular design method is used to control the operation of the terminal,and the program and communication protocol of the function module are designed to realize the transmission of data acquisition on the cloud platform.A client software architecture based on producer-consumer and state machine is proposed to solve the problem of asynchronization between detection process and user interaction events and data processing,which ensured the efficient parallel operation of automatic control of detection process and user interaction events.The detection waveform is denoised by calling MATLAB filter program,and functions such as generating reports and saving data are designed to meet users’ demands for various detection tasks.(4)The system is debugged to verify the performance of each module,and field tests are carried out on the pipeline with artificial weld defects and artificial hole defects.For the same pipeline,four channels of excitation were used firstly,and the stable detection value was obtained by using 70-110 k Hz excitation signal.The error range between the detected value and the actual pipeline defect position at the used frequency met the detection accuracy requirement of ±0.5%;Then using symmetric dual channel signal incentive found that due to incentive the decrease in the number of sensors,wave amplitude detection results about down to four channels of excitation amplitude 1/2,but defect detection value corresponding with all channel detection,multi-channel contrast test to verify the system stability,accuracy and reliability of the detection performance,several rounds of the test results show that the system performance to meet the design requirements.