Study On Multiphysics Coupling Mechanism Of Laser In-situ Molding Process Of CF/PEEK Composites

With the continuous development of advanced aerospace manufacturing technology,thermoplastic composite materials with high toughness,strong corrosion resistance,high damage tolerance and reusability have begun to receive extensive attention from relevant researchers.Laser in-situ molding technology has the advantages of instantaneous high temperature,precise and controllable heating area and temperature,and high molding accuracy,which is an ideal means for additive manufacturing of high-performance thermoplastic composites.The distribution of temperature,fluid and stress fields inside thermoplastic composites greatly affects the molding quality,so revealing the characteristics and coupling mechanisms of each physics of the molding process is of great significance for achieving high-quality laser in-situ molding.Based on COMSOL Multiphysics finite element simulation software,this paper studies the multiphysics coupling mechanism of CF/PEEK composites in situ molding process.The main work of this paper includes the following two aspects:(1)In order to reveal the solid-flow coupling mechanism of CF/PEEK composites in situ molding process,the geometric model of CF/PEEK composites and its three-dimensional transient heat transfer model were constructed,and the temperature field distribution and phase transition process of CF/PEEK composites under the action of flat-top laser beams with different power densities,velocities and motion angles were simulated by COMSOL Multiphysics finite element software.By analyzing the influence of laser process parameters on the surface temperature field and solid and liquid phase distribution of CF/PEEK composites,the coupling mechanism of surface temperature field-fluid field of CF/PEEK composites in the process of laser in-situ molding was revealed.The results show that the maximum surface temperature and molten area of CF/PEEK composites increase with the increase of laser power density and decrease with the increase of spot movement speed.When the spot moves at 45°,the surface temperature of the material is highest and the molten area is the largest.(2)In order to reveal the thermo-mechanical coupling mechanism of CF/PEEK composites in situ molding process,a two-dimensional homogeneous equivalent model was constructed,and the thermo-dynamic coupling characteristics of CF/PEEK composites in situ molding process were simulated by COMSOL Multiphysics finite element simulation software,the temperature and stress distribution inside CF/PEEK composites during molding were studied,and the distribution characteristics of surface temperature field and thermal strain during insitu molding of composites were analyzed.The coupling relationship between the two was studied;On this basis,the residual stress generation mechanism and distribution characteristics of CF/PEEK after molding are analyzed,and the residual stress distribution inside the composite components after cooling is simulated.The results show that the ply temperature increases with the increase of the number of plies during the pavement molding process.After cooling consolidation,the residual should appear at the maximum value on the far left of the first layer.This study aims to reveal the multiphysics coupling mechanism of CF/PEEK composite laser in-situ molding process,and provide a theoretical basis for the laser in-situ molding process of thermoplastic composites.