Creep behaviour data presentation

These latter curves are particularly important when they are obtained experimentally because they are less time consuming and require less specimen preparation than creep curves. Isochronous graphs at several time intervals can also be used to build up creep curves and indicate areas where the main experimental creep programme could be most profitably concentrated. They are also popular as evaluations of deformational behaviour because the data presentation is similar to the conventional tensile test data referred to in Section 2.3. It is interesting to note that the isochronous test method only differs from that of a conventional incremental loading tensile test in that (a) the presence of creep is recognised, and (b) the memory which the material has for its stress history is accounted for by the recovery periods. 

Although there are no data for the creep behaviour of solution-spun or gel spun fibres of a comparable nature to those for the melt spim and drawn materials, a few results can be presented. 

A major problem in data presentation for anisotropy of creep behaviour arises from the dependence of behaviour on many parameters. In Section 10.2 the modulus for a given degree of molecular orientation under given environmental conditions for a single material was given as a function of angle, time and either stress or strain whilst the material compliance functions for these conditions were functions of time and stress or strain. Changes of temperature, composition, orientation, structure, etc., will of course affect the whole pattern of behaviour. 

The linearity of the creep data presented on a log-log scale is consistent with the behaviour represented by the power law equation. 

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