Simulation And Experimental Study On Ultrasonic Sound Field Distribution And Defect Echo Respond Of Small Flaws In Materials Based On CIVA

The study of this article is funded by several national and provincial research projects.In this article,metal plates and bars and carbon fiber composite material are regarded as the research object,using the method of CIVA simulation and experimental verification combined to investigate the ultrasonic sound field distribution and small flows in ultrasonic echo response in materials.In the calculation of ultrasonic sound field,the quantitative relationship between the sound field distribution and the workpiece,probe and detection parameters is obtained by using the ultrasonic propagation model which is applicable to all kinds of probes and propagation medium based on the Rayleigh integral(Rayleigh Integration Method,RIM)model modified by the Pencil method.In order to solve the problems in practical engineering application that it is difficult to calculate the analytical solution due to the complexity of defects or structure,Kirchhoff approximation and the Born approximation theory are introduced and scattering model of defect and structure is established,which makes the fast calculation of complex defects and the scattering sound field possible.Carbon steel bar model and aluminum plate model for metal materials are established in which some defects in the important and common metal materials,such as slag and crack,are taken as cylinder defects.The effects of various detection conditions on the sound field distribution and on the response of defects in metal materials with artificial defects is calculated and analyzed by using ultrasonic simulation software CIVA.A water immersion ultrasonic detection platform based on pulse reflection method has been built.The ultrasonic inspection of defect echo is verified by experiments using test specimens of 20#steel bars with 0.8mm diameter flat bottom holes and square aluminum plate.Ideal model of 32-layer thin plate defect free CFRP laminate and 72-layer thick section CFRP model of artificial defects with flat bottom hole is established for carbon fiber composite.The simulation and analysis of sound field distribution and defect response are carried out by using CIVA simulation software,and the corresponding ultrasonic detection experiment was carried out by using the self-designed ultrasonic detection platform.In conclusion,this article mainly established the simulation and experimental study on ultrasonic sound field distribution and defect echo respond of small flaws in materials based on CIVA platform;Studied a variety of detection conditions on the distribution and the defect echo respond of metal and composite materials and got the key impact factors,which provides theoretical guidance for how to choose appropriate parameters of ultrasonic probe detection.