Research On Uncertainty Inverse Of Potential Function Parameters Of Iron Material Based On Molecular Dynamics

With the development of science,the research and application of iron material and their alloy material may be progressive.And with the development of computer hardware and software technology and the advancement of network technology,molecular dynamics has become more and more prominent in the development of new material,showing its unique advantages.Molecular dynamics involves many technologies in different research directions,but the potential function has become the focus of many studies because it has a decisive influence on the entire molecular dynamics calculation results.Especially,the optimization of the parameters of the potential function is still a hot spot for people today.The main research work of this paper focuses on the optimization of potential function parameters,especially the introduction of uncertainty inverse technology as an optimization method.The main work of this article includes the following aspects:(1)Based on the molecular dynamics research method,through the comparison of relevant experiments and the parameters of iron material,the research object of this paper is determined to be the iron material model under molecular dynamics.Then,the expression of the iron material molecular dynamics potential function is analyzed,and the iron material is modeled according to the principle of molecular dynamics,and the unknown model parameters and physical properties of the iron material molecular dynamics model are obtained.By taking different values of the model parameters and calculating their corresponding model physical properties,the model physical properties are affected by the fluctuations of the model parameters,and the optimal model parameters are selected.(2)Sensitivity analysis of the model parameters and physical properties of the iron material to determine the reverse target and optimization target.By establishing the optimal polynomial model to avoid the black box of the molecular dynamics model,the polynomial model of the iron material is directly integrated and solved based on the Sobol method,and its sensitivity relationship is solved by analyzing its variance.Based on the results of the sensitivity analysis,the parameters and physical properties of the model to be reversed with a strong sensitivity relationship are selected.(3)Combining the characteristics of the uncertainty of the molecular dynamics model and the results of the sensitivity analysis,the uncertainty potential function parameters in the iron material model are determined and the uncertainty is measured.Based on the chaotic polynomial method,the polynomial model of the iron material is chaotically expanded,and the mean and variance of the model's uncertainty potential function parameters are transferred to the calculation results of the physical properties of the model through the characteristics of the chaotic polynomial moment transfer,and the mean and standard deviation are analyzed.The confidence interval is used to characterize the influence of the uncertainty of the potential function parameters of the iron material on the calculation results of its physical properties.(4)Combining the results of sensitivity analysis,inverse seeking the potential function parameters of the model to be inverted.Combined with the analysis results of uncertainty propagation,the mean and variance of the uncertainty parameters are transferred based on the point estimation method,and the solution of the inverse uncertainty of the potential function parameter of the iron material is transformed into the solution of its deterministic inverse problem.It is optimized and solved by least squares method.After solving the mean and standard deviation of the inverse potential function parameters,the confidence interval is used to characterize the influence of the uncertainty of the potential function parameter of the iron material on other potential function parameters.