Research On Ultrasonic Detection Of High-speed Train Aluminum Alloy Material

With the continuous development of economy, the rapid rise of modern industry, aluminum alloy material has been widely used in aerospace, high-speed train, ship, rail transportation, automobile and other fields.In this paper, we use ultrasonic Lamb-wave of aluminum alloy sheet metal testing, modeling and simulation by using ANSYS to calculate the different defects, sensor model, and the results of simulation experiment system of verification.Using ultrasonic sensors moving measuring plate active detection, through to the transmit and receive signal processing, multipath method to locate and detect the size of defects, and focus on the ultrasonic signal of multiplicity provide additional data on the influence of the defect location and dimension.This paper studies the main contents include:(1) Studies the parameter selection and transmitting window handle, smooth processing of received signal of the delay time by the maximum method and Hilbert transform, estimates that by finding corresponding difference in the presence of defect cases to extract the defect echo, etc.And study more modal characteristics of Lamb waves are discussed, such as velocity and attenuation problem.(2) Using ultrasonic multiplicity method to located and detect the size of defects, using ANSYS analysis on flawed and infinite defect model was established on the basis of through finite element node receives the echo to extract the defect echo of a plate, according to the defect echo time, through the calculation of method of multiplicity, get the coordinates of the sheet defects and size. When the model for the same sensor position and defect position different defect size sheet defect model, extracted the flaw echoes in the model, and determine the DRP and MP-W path delay time, the defect is obtained, the greater the effect of ultrasonic Lamb wave test way go, the better, the result more accurate, illustrates the theory of multiplicity detecting single Lamb wave measurement analysis in detecting defects in aluminum alloy sheet is feasible.(3) Using the ANSYS finite element simulation software for two different types of simulated calculation sheet model, one is when the defect is changeless, sending and receiving sensors to move gradually, simulation is conducted for each model, get when sending and receiving sensors is located in the upper and lower boundary of multiplicity detection effect is best; Another kind is when sending and receiving sensors at constant, the size of the defect is changeless, center coordinates, gradually to the direction, for each model are simulated, get when defects closer to the center of the center of the sheet, the detection effect.(4) To construct a system of ultrasonic Lamb testing.Through experimental analysis compares the three different frequency of excitation signal in the property of the sheet; Different model is established, the ultrasonic defect echo, oily and defects for the successful positioning and calculate its size.Main validation send and receive the same sensor location, different defect size model, as well as when sending and receiving sensor position unchanged, defects from sheet center gradually to the direction of each model. Experimental results are broadly consistent with the ANSYS simulation results, proved that the ultrasonic multiplicity test in the application of aluminum alloy sheet is feasible, the defects by ultrasonic way to locate and accurately calculate the size. By a multiplicity of ultrasonic testing can determine the crack location, using traditional technology can identify the direct reflection path (DRP); Can be determined through the DRP in the range estimate and MP-W delay time, detection of defects at the top of the DRP can use, at the same time the bottom of the use of MP-W testing. According to analyzing the way of multiplicity and signal modeling, can further study because of multiplicity provide additional data, these data provide and ensure the possibility of a single defect measurement is identified and uniqueness, and calculate the size and location of the material defects.