期刊
MECHANICS OF MATERIALS
卷 78, 期 -, 页码 44-55出版社
ELSEVIER
DOI: 10.1016/j.mechmat.2014.07.017
关键词
Internal variable theory; Creep damage model; Flow potential; Energy dissipation rate
资金
- National Natural Science Foundation of China [11172150, 51279086]
- State Key Laboratory of Hydroscience and Engineering [2013-KY-2]
- program for New Century Excellent Talents in University [NCET-13-0323]
The creep damage is discussed within Rice irreversible internal state variable (ISV) thermodynamic theory. An ISV small-strain unified creep model with damage is derived by giving the complementary energy density function and kinetic equations of ISVs. The proposed model can describe viscoelasticity and, preferably, three phases of creep deformation. Creep strain results from internal structural adjustment, and different creep stages accompany different thermodynamic properties in terms of flow potential function and energy dissipation rate. During the viscoelastic process, the thermodynamic state of the material system tends to equilibrate spontaneously. The thermodynamic state of the material system without damage tends to equilibrate or achieve steady state after loading. Kinetic equations of ISVs can be derived by one single flow potential function, and the energy dissipation rate decreases monotonically over time. In the entire creep damage process, multiple potentials are needed to characterise evolution of ISVs, rotational fluxes are presented in affinity space, and the thermodynamic state of material system tends to depart from the steady or equilibrium state. The energy dissipation rate can be a measure of the distance between the current thermodynamic state and the equilibrium state. The time derivative of the rate can characterise the development trend of the material, and the integral value in the domain may be regarded as indices to evaluate the long-term stability of the structure. (C) 2014 Elsevier Ltd. All rights reserved.
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