The isochronous stress/strain curve is a long established method of representing creep data in a manner which, under certain circumstances, provides a quick and often surprisingly accurate approximate solution to time dependent structural problems. Despite criticisms of the foundations of the method, it has survived over the years because it has either been the only method feasible at the time, or it is capable of providing solutions which are often good enough for practical purposes. This paper plans to trace the evolution of structural analysis based on isochronous curves, examining its boundaries of application and the circumstances under which it might be expected to yield plausible answers. Different types of isochronous curves will be described, together with procedures for constructing them from different forms of material data such as constant strain rate tensile tests. Special attention will be given to the representation of tertiary creep in the form of isochronous curves, and how such curves might be used in carrying out simplified analyses of propagating creep damage in complex components. Recent extensions to the original methodology to include variable load and thermal histories will be examined. Possible applications in the emerging field of very high temperature applications, as are expected to be experienced in Gen IV nuclear plant in the future, will be reviewed, with special attention given to the problem of rate dependent short term properties, which looks to become a serious question in development of design allowables for very high temperature applications.

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