Research On Inverse Optimization And Application Of Key Thermal Parameters In Casting Simulation

Casting defects prediction and research using computer numerical simulation technology has been widely used in practical production.The numerical algorithm for casting temperature field simulation has been matured so far.The main error sources of temperature field between numerical simulation and actual production are inaccuracy of material physical parameters and boundary conditions.To get accurate temperature field simulation results,one need to enter accurate material thermal property parameters and boundary conditions.Due to the complex and variable casting factory,if the empirical values are used to simulate the casting temperature field,there is often a certain deviation from the reality.Therefore,it is necessary to check the material physical parameters and boundary conditions.However,for the required thermal property parameters and boundary conditions for casting simulation,it is difficult to directly measure by experiment,and even some parameters are theoretical parameters,which cannot be directly measured by experiments.In this paper,the QT400-15 furan resin-bonded sand gravity casting experiment was designed and put into practice,the thermocouple was used to measure the temperature of some key locations inside the sand and cavity.According to the designed experimental model,the numerical model of the temperature field was established,and the ProCAST casting simulation analysis software was used to set and calculate the numerical model with the empirical values.Comparing the calculated temperature curves with the measured temperature curves,it was found that there was a big difference between the simulated temperature curves and the measured temperature curves.Based on the experimental model,an inverse mathematical model was established.A DOE(Taguchi Method)sensitivity analysis model was used to analyze the sensitivity of each factor to find some key factors that are sensitive to the temperature field of the model.With the measured temperature curves as the initial input condition,the thermal property parameters and boundary conditions were inversely calculated according to the sensitivity to temperature from high to low.Therefore,the purpose of avoiding direct measurement of the experiment but inversely calculating the thermal property parameters and boundary condition parameters by the measured temperature curve is achieved.The thermal property parameters and boundary conditions obtained by inverse calculation were applied to the actual production of castings for simulation analysis and comparison with reality to verify the accuracy and practicability.The verification results show that the thermal properties and boundary conditions obtained by the inverse calculation can match the actual production.It is proved that the key factors affecting temperature results can be determined by DOE sensitivity analysis method.It is also proved that the application of inverse algorithm can optimize the key thermal properties and boundary conditions of casting simulation efficiently.Finally,based on the inverse calculation of the optimized thermal parameters,the ProCAST casting simulation software was used again to study the shakeout temperatures of the fuselage casting to analyze the effects of different shakeout temperatures on the stress and strain.The results show that the higher the shakeout temperature,the lower the effective stress and strain before sand shakeout,the lower the residual stress of the casting at room temperature,but the greater the final deformation.