Effective Maxwell equations from time-dependent density functional theory

The behavior of interacting electrons in a perfect crystal under macroscopic external electric and magnetic fields is studied. Effective Maxwell equations for the macroscopic electric and magnetic fields are derived starting from time-dependent density functional theory. Effective permittivity and permeability coefficients are obtained.Comment: 36 page

The Interpretation of Experimental Observation Data for the Development of Mechanisms based Creep Damage Constitutive Equations for High Chromium Steel

It is very important to design a safe factor or estimating the remain lifetime for electric power plant components of steam pipes which mostly manufacture by high chromium steels and work at high temperature and low stress level. The author will develop the mechanisms based on creep damage constitutive equations for high chromium steel under lows stress in initial stage: (1) Creep cavities mostly formed attaching with the precipitation of Laves phase or on grain boundary for high chromium steel under low stress. The Laves phase should play an active role in the nucleation of creep cavities and suggest to explore the function between cavity nucleation and the evolution of Laves phase; (2) The dominant cavity nucleation mechanism is adapted to high chromium steels under low stress level; (3) Brittle intergranluar model is appropriate for high chromium steels at high temperature under low stress level; (4) High density number of cavity of crept test high chromium steel at high temperature under low stress could be as fracture criterion

The Development and Validation of the Creep Damage Constitutive Equations for P91 Alloy

This paper presents research on the validation of a set of creep damage constitutive equations for P91 alloy under multi-axial states of stress, and its applicability under lower stress level. Creep damage is one of the serious problems for the high temperature industries and computational creep damage has been developed and used, complementary to the experimental approach, to assist safe operation. In creep damage mechanics, a set of constitutive equations needs to be developed and validated. Recently, a mechanism based approach for the developing creep damage constitutive equation for this type of high Cr alloy has merged and several versions of creep damage constitutive equations have been proposed. However, so far, they are limited to uni-axial case under medium to high stress level. In fact, multi-axial states of stress and lower stress level are more pertinent to the real industrial applications. That is the objective of this research. This paper contributes to the methodology and specific knowledge

The relative significance of internal damage mechanisms on the overall creep damage and ultimate failure of P91 steel

This paper reports research on the study of the relative significance of various internal creep damage mechanisms on the overall creep damage and lifetime of P91 steel. The study is essentially parametric investigation based on the individual internal creep damage mechanisms and phenomenological modelling of creep cavity damage. The simulated results do show the importance of the cavity damage among all the creep damage mechanisms. However, more importantly, it also points out the deficiency in the latest approach of phenomenological approach of modelling cavity damage over a wider stress range, and addresses the necessity of considering and incorporating the micromechanics/mechanism of nucleation, growth, coalescence into the creep damage constitutive modelling work. This paper contributes to the knowledge and method for creep damage mechanics