A method to determine the material constitutive model parameters of FGH4095 alloy treated by laser shock processing

Abstract

In order to determine the material constitutive model parameters of FGH4095 alloy treated by laser shock processing (LSP), the Johnson–Cook (J-C) plasticity model was selected. The strain hardening function parameters A, B and n can be determined form true plastic strain-stress curve. In this work, the engineering stress–strain stress curve was obtained from China Superalloys Handbook, which was converted into a true strain-stress curve, and then the elastic part of this curve was removed to obtain the equivalent plastic stress–strain. Parameter A is the initial yield stress in true plastic stress–strain curve, parameter B and n were determined by least square method of f1(ɛ)=A+Bɛn in the true plastic stress–strain curve. For the determination of parameter C, a method based on LSP experiment and LSP numerical simulation was proposed. We assumed the initial predicted value of parameter C is 0.0015, and then the numerical simulation work was undertook with the change of predicted value of parameter C until the error of the maximum compressive residual stress obtained by experiment and simulation falling into allowable range (±1%), and then the parameter C was determined. At the end, the J-C plasticity model parameters of FGH4095 alloy with A = 1057 MPa, B = 1420 MPa, n = 0.3625 and C = 0.011 were determined, which has important reference value and guiding significance for researchers to carry out the LSP numerical simulation work.