Study On Heat Transfer And Its Numerical Simulation Of The Fused Deposition Modeling Process

Fused deposition modeling(FDM)technology is a rapid prototyping manufacturing technology which in recent decades at home and abroad has a wide application,can adapt to the competition globalization of the manufacturing field,individuation and diversification of users' demand,reduce production cost,improve production efficiency,fast response to the changes in market demand.The fused deposition modeling technique is based on the principle of discretion/accumulation,by 2D section layer forming three-dimensional solid,easy to produce the ladder effect,resulting in war-page and other defects.In the process of forming,the change of the temperature field is directly related to the stress field and strain field,so it is very essential to analyze the heat transfer in the forming process.In the process of forming,the surface heat transfer coefficient is an important boundary condition.At present,the research on the heat transfer coefficient of the surface in the process of melting deposition is relatively scarce,and the inaccurate heat transfer coefficient seriously influences the analysis of heat transfer process,which seriously affects the analysis of the various defects.The research on the surface heat transfer coefficient in the process of melting deposition has been imperative.This paper is based on the first law of thermodynamics and the law of conservation of energy and other related theories,analyzes the heat transfer of FDM,establishes the relevant mathematical model,based on the related theory about the finite difference method and heat transfer,considering the change of thermal physical parameters of material and the effect of internal heat source and the latent heat of melting,derives the control equations of heat transfer during melting deposition..This paper used the finite difference scheme to replace the heat transfer equations and nonlinear iterative estimation principle,put forward the FDM solving inverse problem of the surface heat transfer coefficient,preparation of FDM surface heat transfer coefficient of the inverse program by using MATLAB software,solved the variation law of the surface heat transfer coefficient with time and temperature and the finite difference division of temperature at different nodes with the change of time.In the process of forming the experiment,the temperature value of some nodes in the forming part is measured by the temperature acquisition system.The relationship between the temperature calculated value and the measured value at the same node in the verification and reverse procedure is obtained.The reverse procedure which is reasonable and effective is derived.This paper is based on the analysis of the forming characteristics of the fused deposition process,and put forward reasonable assumptions,establishes the finite element model,analyzes the heat transfer of the fused deposition modeling process.Using the life and death element technology of ANSYS finite element analysis software,combined with the actual scanning style and scanning speed in the process of forming experiment,programmed by APDL parametric design language,used the surface heat transfer coefficient which has been solved as the boundary condition,solves the temperature field of the model,simulates the temperature gradient distribution of different time and the temperature varies with time at different nodes,provides a theoretical basis for the stress field and strain field,etc.The simulation results are in good agreement with the actual situation,which shows the surface heat transfer coefficient is valid.