Numerical Simulation Of Casting Deformation And Thermal Stress Based On Equivalent Particle

The unreasonable distribution of casting thermal stress may lead to casting defects such as residual stress concentration,cracking and deformation.The staff need to carefully consider in the process design stage to avoid the above casting defects,and the trial and error method with complicated process,high time and economic cost has to be used to optimize the process.The numerical simulation technology of thermal stress in casting process provides powerful technical support for solving this problem.At present,the numerical simulation technology of thermal stress in casting process is in the transition stage from scientific research to engineering application,and there is still no mature treatment method for some key problems.For example,it is difficult to obtain the constitutive model and corresponding physical parameters of metal solid-liquid coexistence zone;The contact model of casting / mold is complex,so it is necessary to simplify the hypothesis processing at present.The contact element method with high accuracy has a large amount of calculation and poor convergence;In order to constrain the degree of freedom of solid,additional point / surface solid positioning constraints are required to be applied to the fully regressive boundary;The complexity of casting structure leads to the increase of the number of pre-processing grids,which further leads to the excessive consumption of calculation time,etc.Under these conditions,based on the mature research results of FDM numerical simulation of casting heat transfer and flow,this paper independently developed the numerical simulation software of casting deformation and thermal stress based on equivalent particle method under Windows platform,which can better support the fully regressive boundary conditions without additional constraints;The pre-processing module is flexible and simple,and can generate other kinds of grid directly;Compared with a numerical simulation software of casting thermal stress based on finite element method,the software has higher calculation efficiency.Firstly,based on the assumption of unidirectional thermal mechanical coupling and the basic assumptions of temperature and stress fields in the casting process,the equivalent particle method is proposed,and the storage method of equivalent particle set in memory is introduced.On the premise that the first storage method wastes memory,the second storage method is created by introducing auxiliary data structure,When the number of finite difference grids is about 100 W and the proportion of casting grids is about 30%,the memory consumption of the second storage method is only 31% of that of the first.Secondly,based on the mature research results of numerical simulation of casting temperature field,the solution method of casting deformation and thermal stress based on equivalent particle method and the correction method of plastic deformation are studied,and the numerical simulation software of casting deformation based on equivalent particle method is developed,by comparing with ANSYS,the accuracy of the software is proved.Thirdly,this paper studies the parallel performance of the casting deformation solution method,establishes the accelerated calculation method based on multi-core parallel and the accelerated calculation method based on optimizing the iterative coefficient and increasing the mass connection relationship.Through the comparative analysis of the examples,it is proved that the accelerated algorithm has high computational efficiency.The time consumption of PNO algorithm is only about 39% of that of Sn O algorithm,and that of PO algorithm is only about 18% of that of Sn O algorithm.Finally,the fixed end swing casting is selected to check and verify the software,and the deformation of the casting during solidification is simulated.The results show that the simulation results are in good agreement with the actual situation,and the accuracy of the software is preliminarily verified.Then,the deformation of the support frame casting was predicted and analyzed,and the deformation data of the casting was obtained by 3D scanning.The results show that the predicted results are in good agreement with the measured results.In conclusion,the numerical simulation software of casting deformation developed in this paper can provide scientific guidance for optimizing process,reducing time and economic cost,and improving production efficiency in production practice.