Thermal-mechanical Coupling Mechanism Of Composite Ultrasonic Oscillator Of Metal Additive Manufacturing

Metal additive manufacturing technology has a broad application prospect in the fields of aerospace,automobile manufacturing,bio-medical treatment and so on.It is of epoch-making significance to promote the innovation of traditional manufacturing industry in China.With the continuous updating and iteration of related technologies,metal additive manufacturing technology has achieved phased results.However,due to the rapid development of related fields,the processing and manufacturing of metal complex components and the preparation of composite materials have almost demanding requirements,domestic and foreign manufacturers began to seek a more efficient,green,energy-saving processing technology-ultrasonic consolidation metal additive manufacturing technology.This paper focuses on the composite ultrasonic piezoelectric oscillator which is the core energy conversion component in ultrasonic consolidated metal additive manufacturing technology.The amplitude and heat transfer changes of the ultrasonic piezoelectric vibrators under the complex boundary conditions such as mechanical loading,prepressure,friction and dielectric loss of materials are studied.From dynamics and heat transfer theory,researches the key technology of the compound ultrasonic oscillator,by adopting the combination of numerical simulation and experimental validation method to establish and perfect the metal temperature field simulation model of consolidation area,aims to reveal the compound ultrasonic oscillator under the condition of complex thermal coupling vibration characteristics and heat transfer law,for the metal layered composite material,intelligent material,the preparation of fiber reinforced composite material,the development of efficient and stable compound ultrasonic oscillator provides the theoretical foundation.The specific work is as follows:Based on the research status of the ultrasonic consolidated piezoelectric oscillator subsystem,the research on the ultrasonic piezoelectric oscillator,the core part of the system,is summarized and analyzed.The second is the lack of a heating model of piezoelectric vibration system,which leads to the unclear influence law of heating phenomenon and dynamic performance in the process of ultrasonic consolidation.With push-pull type compound ultrasonic piezoelectric vibrator as object,from the two aspects of statics and dynamics to explore the stator in ultrasonic consolidation area at the mechanical behavior,using commercial finite element analysis software ANSYS to establish the structure of ultrasonic piezoelectric vibrator model,the analysis of piezoelectric vibrator work under different excitation voltage and temperature boundary conditions of modal vibration mode and vibration frequency,it is concluded that the oscillator amplitude decreases with the increase of excitation voltage increases,the positive pressure is 1 kN,50 V voltage rise,increase amplitude corresponding to 3 microns;The temperature affects the resonance frequency by changing the properties of piezoelectric ceramic materials.When the temperature increases by 20? and the density decreases by 100kg/m3,the resonance frequency correspondingly increases by 13Hz.Reference dynamics simulation model is set up the experiment,this paper introduces the process of preparation of ultrasonic piezoelectric vibrator model,and through the impedance analyzer and scanning laser doppler vibration experiments for the prototype model of the vibration mode and vibration frequency,and compared with the simulation model,the vibration frequency,relative error is about 8%,verify the validity of the simulation model.The energy conversion mechanism of the ultrasonic consolidated piezoelectric vibration subsystem is studied,the main source of heat energy is analyzed and its quantitative calculation method is used.The influence of different heat sources on the temperature of the piezoelectric vibration subsystem was analyzed,and the temperature changing process with time before the ultrasonic vibration system reached the thermal equilibrium was studied by steady state and transient state analysis,and it was concluded that the pre-heating effect of the substrate would affect the temperature change in the consolidation region.