Research On Internal Acoustic Focusing Method And Simulation Based On Temperature Gradient

With the iterative update of technology,more and more new materials are applied to various fields,but many materials are non-metallic or very low-hardness metals,which cannot be directly processed with tools,but traditional processing methods cannot be solved well.For example,biological tissue,liquid metal,especially for non-uniform media,the corresponding mechanical properties of each medium are different.When the tool processes the non-uniform media,the tool will be damaged due to the different mechanical properties of the medium.,so a new type of processing technology is required.Because ultrasonic machining can directly process the parts without tools,the internal effects of the object are processed to form various microstructures through the thermal effect of acoustic focusing,becoming a material.A processing method for internal processing,but ultrasonic internal processing often requires acoustic wave focusing to achieve energy concentration to process the interior of the part,but the acoustic focusing method mainly uses ultrasonic phased array focusing to affect the ultrasonic phased array There are many factors for focusing.First,the arrangement of multiple sound sources affects whether the sound wave can be focused.Secondly,the position of the focus point is not easy to adjust.At the same time,when the medium contains obstacles,the sound wave cannot be adjusted to adjust the sound wave.Focus around obstacles.This leads to the core problem of this article,that is,how to form an acoustic focus with a high transmission coefficient and a low reflection coefficient.At the same time,when the medium contains an obstacle,the acoustic wave can be adjusted to make the sound wave bypass the obstacle to form a focus.This paper proposes a method to reduce the acoustic reflection coefficient by temperature and adjust the deflection of the acoustic wave to form a focus.When the material contains an obstacle,the method of adjusting the temperature gradient so that the acoustic wave bypasses the obstacle and reforms the method of focusing.The full text of the study is as follows:1.Use the lens to form the acoustic focus.In this paper,starting from the law of sound wave propagation in an ideal fluid,the law of sound wave propagation in different media is deduced.The effect of temperature on sound wave deflection and the sound reflection coefficient are further derived.The parametric curve is used to divide the medium area into two areas to form an acoustic lens.,A constant temperature is set in one of the areas,and the other area is normal temperature.The multiphysics coupling simulation software COMSOL is used for numerical simulation of acoustic focusing with added temperature and acoustic propagation without added temperature.The influence of the direction of propagation is further explored on the effects of different frequencies and different temperatures on the sound pressure and sound intensity at the focal point.2.Acoustic focusing with discrete temperature gradients.Based on the generalized Snell's law,the propagation rule of sound waves in metamaterial surfaces of different materials is derived.The metamorphic surface is used to design a transmission unit,and different constant temperatures are set in the transmission unit to form a discrete temperature gradient.The effect of sound wave deflection makes the sound wave focus in the air.The simulation software COMSOL is used to perform numerical simulation to verify the theory and explore the effect of different frequencies on the sound intensity at the focus point.3.The sound waves are focused in 45# steel containing a circular cavity.Based on the theory of acoustic wave scattering and diffraction,the effect of circular cavities of different radii on acoustic focusing is explored without focusing.The speed of sound is adjusted by temperature,and then the deflection of the sound wave is adjusted so that the sound wave is refocused and verified by numerical simulation.