Ultrasonic Flaw Detection Field Simulation And Experiment Based On Multi-Gaussian Method

Ultrasonic field detection has a wide application in the field of non-destructive testing,medical field and ocean acoustics.The performance of the transducer directly affects the accuracy of the system.However,this can be evaluated by analyzing the ultrasonic field distribution of the transducer.The simulation of ultrasonic field can be used to assist the nondestructive testing system.and the simulation results can be used as a reference for the ultrasonic field measurement of the transducer.But there are several problems in applying the ultrasonic field theory to the simulation.First,the ultrasonic field theory’s deduce need taking the simulation speed and accuracy into account;Second,the model need to be applied to complex application scenarios,especially different media’s ultrasonic field;Third,the accuracy of the model should be verified experimentally.In order to solve the above problems,this article has done the following work in a targeted manner:(1)Starting from the basic equation of ultrasonic wave,analyzing the propagation equation of ultrasonic wave in solid and liquid,using the paraxial approximation,simplifying the calculation and obtaining the single Gaussian beam equation,the multi-Gaussian beam superposition model is established by superimposing a single Gaussian sound beam with a set of superposition coefficients.Simplification of the multi-Gaussian beam model allows the model to make full use of computer performance for fast calculations.In addition,this paper also adjusts the coefficient of the multi-Gaussian beam,and expands the transducer type of the ultrasonic field simulation from the flat transducer to the focus transducer.The model can be used to simulate the ultrasonic pressure distribution in the axial direction and the radial direction,the ultrasonic field distribution of the liquid-solid medium and the focused ultrasonic field distribution.The results are consistent with the experimentally collected ultrasonic field.(2)Comparing the multi-Gaussian beam model with the non-paraxial approximation Rayleigh integral method,the accuracy of the multi-Gaussian model in the 80%region of the near field and the far field can reach 96%.This paper proposes a method to improve multiGaussian accuracy.Optimized the superposition coefficient of multi-Gaussian beam.Analyzed the influence of different number of superposition coefficients on the simulation precision.Correct the loss function of the superposition coefficient on the axial direction,the new superposition coefficient error is 39%lower than the old superposition.(3)Design the hardware,software and mechanical scanning structure of the ultrasonic field measurement platform,builds the ultrasonic field measurement platform.Design the laser calibration device of the transducer and the hydrophone to avoid the problem of direction deviation in the axis scanning process,improve the reliability of the measurement.Measured the ultrasonic field of the transducer by the small ball method and the hydrophone method respectively,and verified the accuracy of the simulation result by experiment.(4)Establish echo simulation model based on multi-Gaussian superposition model,which extends the application range of the multi-Gaussian superposition model.Simulated the flat bottom hole and the side drill hole’s echo and verified the correctness of the simulation by experiment.