Study On Ultraonic Guided Wave Propagation Characteristicis And Excitation Scheme In Elastic Materials

With the rapid construction of Chinese railways,the popularity of high-speed rail is getting higher and higher.Due to the great improvement of the track structure by continuous welded rails(CWR),it can be widely used to meet the relevant plans of the “eight vertical and eight horizontal” high-speed rail network.However,CWR also brings safety hazards while eliminating the rail joints.For example,the temperature stress caused by the temperature difference of the external environment will seriously affect the operational safety of the high-speed railway.A waveguide having a complicated cross section such as CRW.Study the propagation characteristics of ultrasonic guided waves in the waveguide.Establish an index model that selects the guided wave mode.Thereby to develop an optimal excitation scheme for ultrasonic guided waves.Improve the modal complexity of the receiver signal.The above is the focus of this paper.The propagation characteristics of ultrasonic guided waves in elastic materials such as CRW with complex cross-sections are mainly dispersion characteristics and multi-modal characteristics,and the parameters describing the propagation speed of guided waves are phase velocity and group velocity.Based on the semi-analytical finite element method,the propagation characteristics of ultrasonic guided waves in CHN60 rails are studied.The dispersion equation is established by the Hamiltonian principle.A dispersion curve describing the dispersion characteristics is calculated.The multimodal characteristics of ultrasonic guided waves in the rail waveguide are studied by vibration mode analysis and excitation response analysis.At the same time,combined with the actual situation,the propagation attenuation of ultrasonic guided waves in viscoelastic waveguides is studied.Aiming at the problem that the high-frequency guided wave propagates in the elastic material,the mode is numerous and the receiving end mode is difficult to separate.Combining the semi-analytical finite element method and the excitation response analysis,the five coefficients of frequency coefficient,stress sensitivity coefficient,vibration position coefficient,excitation position coefficient and modal identification coefficient are selected to establish the index model,which can guide the formulation of the incentive scheme.Simultaneous simulations verify the effectiveness of the model.Finally,theoretical analysis and experimental verification were carried out on 10# I-beam.The experimental results show that the excitation response analysis can correctly simulate the propagation characteristics of the high-band guided waves in the waveguide.And the indicator model of the selected modality can be used to guide the formulation of the excitation scheme to improve the modal separation problem caused by excessive guided modes of the high frequency band.