クリープ曲線のθ法による推定への非線形計画法の適用

概要

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The θ projection concept, which gives one of creep constitutive equations, can predict various creep curves over a wide range of strain, including the tertiary stage. However, parameter estimation procedures for solving the linearized maximum-likelihood function derived from the original nonlinear equation, involve some numerical difficulties e. g., nonconvergence. In order to improve the accuracy of parameter estimation, to eliminate the numerical difficulties and to be free from approximations by using the original equation as the objective function, the authors have developed two procedures for parameter estimation employing nonlinear programming. One is to estimate material parameters individually for each creep curve. The other is to estimate the coefficients formulating the material parameter as a simple polynomial function of stress and temperature to allow interpolation and/or extrapolation of the material parameter. According to estimation from the strain data referring to the literatures, these procedures can successfully predict the creep curves obtained for some steels.
一般社団法人日本機械学会の論文
1994-04-25