損傷との連成を考慮した金属基複合材料のクリープ構成モデル

概要

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Constitutive models to describe creep deformation and creep damage of unidirectional fiber-reinforced metal matrix composites are developed from a phenomenological point of view. The constitutive modeling is based on the well-established thermodynamic formalism for internal state variable theories. A damage-coupled kinematic hardening model for transversely isotropic materials is first formulated in the invariant form on the basis of the Malinin-Khadjinsky model. An isotropic hardening model is then developed by assuming a particular representation of the kinematic hardening variable. The extent of the composite damage is described in terms of a scalar variable, and a directional effect of the damage on the composite behavior is characterized by a fourth-rank anisotropic tensor. The evolution equation of the creep damage is analogous to the model developed by Kachanov and Rabotnov, but it includes a coupling between creep deformation and creep damage. The analytical expression of the creep rupture time is derived in a particular case of the isotropic hardening model, and for a constant stress creep it depends on both the time and degree of damage at the moment of hardening saturation.
1996-05-25