Simulation Study On Ultrasonic Propagation Characteristics In Ultrasonic Assisted Brazing

With the emergence of ceramics and various new materials and the requirements of modern industry for material preparation and processing,the conventional welding methods in the past can not meet the needs of modern times,so it is necessary to develop a method suitable for both joining new materials and modern industrial needs,this paper takes ultrasonic assisted brazing as the research object,and studies the influence of different ultrasonic amplitudes,different base metal materials,different base metal thickness and different base metal structures on the base metal displacement field and the filler metal sound pressure field.Furthermore,the propagation characteristics of ultrasonic waves in the ultrasound-assisted brazing process are analyzed.The experimental method using finite element simulation provides the necessary research basis for the wide application of ultrasonic assisted brazing.Using COMSOL Multiphysics finite element simulation software,an ultrasonic-assisted brazing model was built.By changing the loaded ultrasonic amplitude,the loaded ultrasonic amplitude sizes were 2.5 μm,5 μm,7.5 μm,and10 μm,and the displacement amplitudes that could be reached on the base metal were 66.14 μm,132.29 μm,198.43 μm,and 264.58 μm,respectively.It was found that the larger the ultrasonic amplitude of the loading,the larger the displacement field of the base metal and the acoustic pressure field of the filler,but did not affect the distribution of these two physics.The influence of base metal material on the displacement field of base metal is mainly reflected in the elastic modulus of the material,the larger the elastic modulus,the stronger the displacement field of the base metal but the weaker the influence effect.The thicker the base metal,the worse the displacement field response of each region of the base metal,and the displacement field strength on the entire base metal is not much different.The main distribution forms of sound pressure field in the liquid filler field are divided into three types: positive acoustic pressure,negative acoustic pressure and zero pressure.Zero pressure is mainly distributed in the area where positive acoustic pressure intersects negative acoustic pressure and the edge area of the filler field.When an ultrasonic amplitude of 2.5 μm is applied,the positive acoustic pressure amplitude in the filler domain is 148.7 MPa and the negative acoustic pressure amplitude is-138.56 MPa.Loading ultrasonic amplitudes of different sizes does not affect the distribution of the sound pressure field in the filler domain,but changes the size of the sound pressure field.Different base metal materials affect the propagation speed of ultrasonic waves in the filler domain and change the size of the sound pressure field in the filler domain.Different base metal thicknesses also affect the amplitude of the sound pressure field.The displacement field of the base metal under different base metal structures is different from the sound pressure field distribution in the filler field,and the displacement field under the foam structure will be weakened by the sound absorption and shock absorption effect of the plate structure during ultrasonic propagation compared with the displacement field under the plate structure,and the weakening effect will be weakened by up to 75%.The sound pressure field of the plate structure is distributed in the form of sheets,while the sound pressure field under the foam structure is mostly distributed in the form of points,but due to the sound absorption and shock absorption characteristics of the foam structure,the sound pressure in the solder metal domain is lower than that under the plate structure.