Study On Theory And Simulation Of Laser-powder Interaction By Coaxial Laser Additive Manufacturing

Laser additive manufacturing is an advanced manufacturing method that uses a laser as an energy source to accumulate materials from the bottom up.This technology is not limited by shape,structural complexity and size,and gets rid of the limitations of traditional "removal" processing methods,and can produce parts with complex shapes that are difficult or impossible to process by traditional methods.Therefore,it has been widely used in aerospace,medicine,automobile,ship,rail transportation and many other fields.The interaction between laser and powder has a great influence on energy utilization,manufacturing efficiency,component quality and so on.Therefore,it is of great scientific significance and engineering application value to study the interaction between laser and powder in the laser additive manufacturing process.In this paper,based on the analytical model and numerical simulation method,the laserpowder interaction mechanism in the continuous coaxial powder feeding laser additive process is deeply studied.The main research contents are as follows:Firstly,an analytical model of the geometrical characteristics of the powder flow with continuous coaxial powder feeding is established,and the analytical expressions of the geometrical characteristics such as the position of the focal plane of the powder flow,the starting and ending positions of the waist region,and the width of the waist are deduced.On this basis,the geometric relationship between parameters such as nozzle size and angle,powder flow divergence angle and the powder flow profile are analyzed in detail.The geometric characteristics of powder flow under typical process parameters are predicted and analyzed.The predicted results obtained by the application are compared with the previous simulation and test results,and the consistency is very high.It verifies the validity of the development formula and provides an important basis for the subsequent analysis work.Secondly,the interaction between laser and powder in the continuous coaxial powder feeding laser additive process is analyzed analytically.The formula for the temperature rises of a single particle after absorbing laser energy is deduced,and the formula takes into account the phase transition of the particle and the change of the thermophysical parameters of the material with temperature.At the same time,from the perspective of shading rate,the attenuation formula of power density and power after the laser passes through the powder flow is deduced.The rationality and effectiveness of the analytical model in this paper are verified by a specific example.Finally,based on the COMSOL Multiphysics software,the interaction between laser and powder in the continuous coaxial powder feeding laser additive process is simulated.A numerical simulation scheme was established,and the effectiveness of the numerical simulation method was verified by simulating the interaction between a single particle and the laser.On this basis,a typical numerical example of continuous coaxial powder feeding laser additive manufacturing was simulated,and good prediction results were obtained.The analytical model and numerical model established in this paper can reasonably and effectively simulate the attenuation of the laser and the temperature rise of the particles after the laser-powder interaction.Developments in laser additive manufacturing research.