Research On Key Techniques Of Numerical Simulation Of Selective Laser Sintering Of Polymer

The thermal-mechanics history in the selective laser sintering(SLS)process is complicated.It is of great significance to study the influence of process parameters on sintering.The main research contents of this article are as follows:(1)Numerical simulation software was developed to simulate temperature field,stress field and warpage deformation of SLS process.The calculation model of temperature field,elastic stress field and warpage deformation was deduced.The calculation model was improved in four aspects: the numerical oscillation problem was improved,the calculation method of the heat flux density was determined,the reasonable grid density was determined,and the loading process of the laser heat source was improved.The results of model was compared with the results of ANSYS software,the correctness of the model was verified.(2)The temperature field,thermal residual stress field and deformation mechanism of warpage deformation during SLS process and the influence of process parameters on sintering were studied.The results show: under the elastic stress field model,the peak temperature,maximum thermal residual stress,and warpage deformation increase with the increase of laser power,decrease with the increase of scanning speed,and decrease with the increase of the uniformity of the scan path.As the number of sintering layers increases,the peak temperature and maximum thermal residual compressive stress both increase first and then reach a more stable value,the thicker the part,the smaller the deformation percentage of the part.Compared with the experimental results of other papers,the accuracy of the model is verified.(3)A viscoelastic experiment of polymer materials was carried out and a viscoelastic stress field calculation model was derived.The differences between the simulation results in the elastic and viscoelastic stress field models and the differences in the influence of process parameters on sintering under the two calculation models were compared.The results show: the influence of process parameters on temperature field and warpage deformation is consistent under the two calculation models;and under the viscoelastic calculation model,the thermal residual stress field is smaller and the warpage deformation is larger,and the influence of process parameters on the thermal residual stress field is not obvious.