Study On High Temperature Mechanical Behavior And Fatigue Life Prediction Of Additive Manufacturing AlSi10Mg Alloy

AlSi10 Mg alloy has the advantages of light weight,high strength,corrosion resistance and good weldability.Additive manufacturing is particularly suitable for the rapid development,rapid verification and design improvement of parts,and supports structural design innovation,is widely used in aerospace,machinery and tooling,national defense,construction and other fields.The service environment of additive manufacturing AlSi10 Mg alloy is extremely complicated.The temperature has obvious influence on the tensile strength and fatigue strength of additive manufacturing AlSi10 Mg alloy.At high temperature,the metal exhibits obvious viscous behavior.Therefore,it is of great scientific significance to study and establish a viscoplastic model suitable for additive manufacturing of AlSi10 Mg alloy,research the influence law of temperature on viscoplastic model parameters and cracking behavior,and explore the fatigue life prediction method for improving the service performance of additive manufacturing parts.In this thesis,Chaboche unified viscoplastic theory,UMAT technique and extended finite element are used to study the high temperature mechanics,fatigue and cracking behavior of additive AlSi10 Mg alloy.The main research contents and conclusions are as follows:(1)The Chaboche unified viscoplastic model was used to simulate the mechanical behavior of additive AlSi10 Mg alloy at different temperatures.The model parameters were established by uniaxial creep and stress-strain cycle experiments,and the functional relations between temperature and each model parameter were derived.Then,the tensile test at normal temperature was fitted according to the equation,and the fitting results verified the accuracy of the equation.(2)Three different metal fatigue life prediction models were used to predict the fatigue life of additive AlSi10 Mg alloy at room temperature.The results show that the K-V model can effectively predict the fatigue life of additive AlSi10 Mg alloy at room temperature.The fatigue life prediction method of notched parts based on plastic zone influence factor was used to predict the fatigue life of additive AlSi10 Mg alloy notched parts,and the influence of notched parts on fatigue life of additive AlSi10 Mg alloy was studied.(3)A central fracture model was established,and the cracking behavior of additive AlSi10 Mg alloy at high temperature was studied by using the expanded finite element method and Chaboche unified viscoplastic model.According to the M integral calculation under different constitutive models and creep conditions,it is found that the viscoplastic model can better reflect the cracking behavior of additive AlSi10 Mg alloy at high temperature than the elastic model.The creep behavior of metal at high temperature obviously affects the crack propagation of additive AlSi10 Mg alloy.