Overstress theories

The quantity a -f(e) on the left, the excess of stress over that obtaining at very slow strain rate, is termed the overstress theories formulated in this way are termed overstress theories. This approach has been applied to metals by Lui and Krempl [39], who used the term viscoplastic to categorise their model. From the form of Equation (11.8), it is clear that... 

The art of developing a good CD model thus lies totally in the chromophore definitions, a factor usually swamped by complex perturbation expressions. The importance of this point cannot be overstressed, as the failure of some CD models stems ultimately from an oversimplified chromophore definition, a deficiency that, in most cases, cannot be remedied by any subsequent theoretical refinements (e.g. going to higher order in perturbation theory). 

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