Research On Multi-parameter Identification In Coupling Thermal Acoustic And Solid Problem

The ultrasonic non-destructive detection technology in high temperature structure has a wide application in aviation,aerospace,medical,mechanical,chemical and other fields.However,the actual engineering usually thickness and boundary heating conditions are unknown at the same time,ultrasonic simultaneous temperature and thickness measurement also faces serious challenges due to the difference of 2-3 magnitudes in the sensitivity of ultrasonic sound time to temperature and thickness.In in high-temperature structures,the problem of simultaneously reconstructing the surface heat flux and the thickness from the associated ultrasonic measurements is essentially a class of multi-target identification inverse problem of initial-boundary value.This paper uses a combination of theoretical analysis,numerical computation,and experimental verification to carry out research on uniqueness,algorithm,and algorithm verification of related inverse problems.First,for the problem of efficient solution of acoustic wave propagation characteristics in ultrasonic high-temperature structure,this paper develops a thermoelastic fluctuation solution method combining tight format and numerical viscosity correction from thermoacoustic coupling theory.Second,through theoretical analysis,in the case of continuous temperature field,the uniqueness of the multi-target inverse problem is proved,which provides an important theoretical basis for the ultrasonic simultaneous temperature and thickness measurement technology in engineering.Finally,the inverse problem is transformed into an optimization problem,and an alternating iterative algorithm for simultaneous identification of heat flux and thickness is proposed.Meanwhile,the effectiveness of the algorithm is proved theoretically through a rigorous convergence analysis.Several numerical and experimental cases show that the method is applicable to the simultaneous temperature and thickness measurement,and has good solution accuracy and noise immunity.14 picture,8 table,71 references...