Study On The Temperature Field During Laser Assisted Tape Placement

Automobile lightweighting is an important way for automobile energy saving and emission reduction,and composite materials are the most ideal solution for lightweighting.Laser assisted tape placement(LATP)technology,as a high-precision,high-automatic rapid composite manufacturing technology,has high heat source efficiency,rapid laying rate and wide application prospect.The temperature field is a key issue in the deposition process,which is related to the melting and polymer chain diffusion processes experienced by the prepreg.Firstly,based on the three-dimensional heat conduction equation,the mathematical model of temperature field of LATP is established.The complex boundary conditions in laser-assisted processing are analyzed in detail.The natural convection and heat radiation in the process of laying are characterized.Through equivalent method,the composite model is transformed into an equivalent homogeneous model with local coordinate system,which greatly improves the calculation efficiency.By using the equivalent calculation and linear interpolation method,the thermodynamic material parameters are piecewise linearized to solve the anisotropic and nonlinear parameter input problem.The simulation model of laser irradiation temperature field is established by ABAQUS software,and the DFLUX subroutine is compiled to realize the secondary development of laser thermal load.In the model,two kinds of light sources with different energy distribution,Gaussian light source and uniform rectangular light source,are simulated.And the characteristics of temperature field produced by two kinds of light sources are compared.A dynamic placement model is established using the life and death technology to simulate the dynamic process of gradual bonding of prepreg tape,which improved the accuracy of the simulation model.Then,based on different processing parameters such as laser power,laying speed and fiber direction,the temperature field of LATP is simulated.Meanwhile,the distribution of transient temperature field and the curve of temperature change with time are obtained.According to the simulation results,the influence of processing parameters on temperature field is analyzed.In addition,based on the model,the multi-layer continuous laying simulation is carried out,and the thermal accumulation effect is analyzed.A laser radiation temperature field measurement device is built by using thermal imager and thermocouple,and the laser radiation temperature field is measured experimentally.The curves of the transient temperature field on the surface and the temperature of the inner nodes with time are obtained.The comparison between the experimental results and the simulation model shows that the two models are basically the same,which shows that the model can effectively simulate the temperature field of the laser processing process.Finally,aiming at the peak temperature and the melting duration,the laser power and the laying rate are optimized.The response surface method is used to obtain the approximate model of the factors and the response.The genetic algorithm is used to analyze the optimization,and the Pareto solution is obtained.The correctness of the optimization data is verified by comparison.In this paper,the influence of laser processing parameters on the transient temperature field and material temperature history is studied and optimized.