Research On Inversion Method Of Constitutive Parameters Of AlSi10Mg Alloy

With the development of computer technology and finite element method,numerical simulation technology has been widely used in the research of train crashworthiness and has become one of the main methods of collision research.In numerical simulation,the constitutive model accurately represents the mechanical behavior of materials is the key to the accuracy of numerical simulation.Aluminum alloy materials have been widely used in energy absorption structures,and AlSi10 Mg alloy is one of them.At present,there are few researches on the mechanical properties of this material.This paper takes AlSi10 Mg alloy as the research object to study its mechanical properties,and proposes a parameter inversion method based on NSGA-algorithm to identify the constitutive model Ⅱ parameters of AlSi10 Mg alloy.The main research content of this paper includes the following two parts:(1)Quasi-static tensile experiment and split Hopkinson pressure bar experiment were carried out on AlSi10 Mg alloy.According to the experimental data,the J-C constitutive model parameters of AlSi10 Mg alloy were fitted,and the fitted constitutive model parameters were verified.(2)An inversion method for constitutive parameters of AlSi10 Mg alloy based on NSGA-Ⅱalgorithm is proposed.The finite element model of the forward problem is constructed according to the split Hopkinson pressure bar experiment,the mathematical model of the inverse problem is constructed from the split Hopkinson pressure bar experiment measurement response and the numerical simulation calculation response,and the mathematical model of the inverse problem is solved by the NSGA-algorithm,so as to Ⅱobtain the material constitutive model parameters,And verify the validity and reliability of the inversion results.The following conclusions are drawn through the research of this paper:(1)At the quasi-static strain rates of 0.01/s,0.001/s and 0.0001/s,the material property parameters of AlSi10 Mg alloy do not change significantly with the increase of strain rates,and the increment of yield strength and tensile strength is small.It is concluded that the material is not sensitive to strain rate at the quasi-static strain rate.(2)Within the 1700/s strain rate covered by the split Hopkinson pressure bar experiment in this paper,the flow stress and dynamic yield strength of AlSi10 Mg alloy have a small increase,and the material has a weak strain rate effect;When the strain rate exceeds 1700/s strain rate,the dynamic yield strength of the AlSi10 Mg alloy increases significantly,showing a certain strain rate sensitivity.(3)By comparing the numerical simulation curve based on the inversion parameter value and the experimental measurement curve under different strain rates,the two stress wave curves have a high coincidence degree,which shows that the parameters obtained by inversion are more accurate,and it proves that the constitutive parameter inversion method of AlSi10 Mg alloy based on NSGA-Ⅱ algorithm proposed in this paper can more accurately determine the constitutive model parameters of the material.