Research On Key Technology And Software Development Of Sound Field Simulation In Thin-walled Tube

With the rapid development of modem industrial technology,the utilization rate of long-distance pipelines is also increasing year by year.However,after several years of service,the accident rate of the pipeline has also increased.How to do the maintenance work of the pipeline is of great significance.Ultrasonic guided waves have a small attenuation along the propagation path,and are usually detected at a point on the workpiece to detect a longer distance.Moreover,it is not necessary to peel off the outer wrapping layer of the workpiece during the inspection,so that the detection is convenient and fast.Therefore,ultrasonic guided wave detection has always been one of the important means of overhauling long-distance transmission pipelines.At the same time,the guided wave has dispersion and multi-modal characteristics.The analysis and control of the guided wave mode is an important measure to improve the reliability and feasibility of guided wave detection.The main research works and innovations of this thesis are as follows:(1)The dispersive and multi-modal characteristics of guided waves are described in this paper.The respective dispersion curves of guided waves in plate-like structures and tubular structures,the wave structures of different modes and the displacement of various modal particles are analyzed in detail,the detection results of different m odes suitable for defects in different directions are obtained.(2)In this paper,the relationship between the dispersion curves of guided waves in thin-walled tubes and thin plates is studied.It is concluded that when the inner-wall thickness ratio of the pipes is a certain multiple,the analysis of thin-walled tubes can generally be regarded as the same thickness plate.The guided wave in the approximation is analyzed to make the three-dimensional problem two-dimensional,which is not only simple to calculate but also easy to understand.Secondly,combined with the finite difference method,the corresponding wave equations of different excitation components in the thin plate structure are obtained.(3)This paper simplifies the vibration model of thin-walled pipe and deduces that the low-frequency zero-order plate wave is non-dispersive.The zero-order plate wave transmitted in two dimensions is repeatedly superimposed along the circumferential direction of the pipe to form a tube wave.The phase velocity and group velocity dispersion formula of the thin-walled pipe are analytical.Through the dispersion formula,the excitation and receiving tube waves can be selected and controlled.Finally,a thin wall tube wave vibration simulation software was developed.The simulation software includes:parameter setting area,sound field propagation control area and sound field propagation condition simulation area.The software can not only select and control the modality,but also realize the unidirectional propagation control of sound waves.