異方硬化クリープ挙動の定式化 : 第1報,理論

概要

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The present study provides a formulation of the creep constitutive equation which is descriptive of anisotropic creep hardening behavior. The basic structure of the model is based on the general framework of irreversible thermodynamics; we define a set of energy-conjugate state variables using the Helmholtz free energy function and the dissipation energy function. The prototypal model of the unified type accounts for combined isotropic and kinematic hardening, and it is applied to a description of anisotropic creep behavior. In order to enhance the predictive accurcy of prototypal evolution equations of the Bailey-Orowan type, we furthermore develop an auxiliary creep hardening rule in general form ; the concept of material memory is introduced where isotropic hardening is suppressed and kinematic hardening is promoted. It is shown that the auxiliary creep hardening rule is applicable to any model of the pure kinematic type. The proposed creep model, which is a combination of the prototypal model and the auxiliary rule, can well reproduce creep softening behavior under complete stress reversals, as in the ORNL creep model.
一般社団法人日本機械学会の論文
1992-06-25