A Unified Approach for Modeling Inelastic Behavior of Structural Metals under Complex Cyclic Loadings.

摘要

This report develops a general procedure for modeling the inelastic stress-strain response of structural metals subjected to complex irregular cyclic loadings. The model is ideally suited for programming on a digital computer and uses 'cyclic'material parameters (or properties) determined from simple constant strain amplitude cyclic tests. Four model formulations which include three degrees of simplification in the model are proposed and their appropriate applications are indicated. In its most complete formulation,the model is capable of simulating all the important observed phenomena of a wide range of structural metals,including hotworked and coldworked steels and aircrfaft aluminums. These phenomena include 'memory'of prior history,cyclic hardening,cyclic softening,cyclic relaxation,cyclic creep,and the observed deviation from the Masing behavior. A major contribution of this report is in the development of a unified characterization of these phenomena. The model and the 'cyclic'material parameters developed provide the necessary base for formulating a general constitutive equation in the multiaxial state of stress. Such constitutive equations are directly adoptable in the finite element codes of nonlinear structural analysis programs. The model is also useful in realistic shakedown analysis of structures and fatigue analysis of complex load histories. (Author)