Viscoelasticity functional interrelationships

FIG. 13.59 Accuracy of interrelationships between static and dynamic viscoelastic functions. 

Lakes R.S. and Katz J.L. 1974. Interrelationships among the viscoelastic function for anisotropic solids Application to calcified tissues and related systems. /. Biomech. 7 259. 

Interrelationships among the Viscoelastic Material Functions. There is a continuing disagreement within the molecular viscoelasticity commimity about which of the above methods should be used to characterize a material (20). In fact, if one can obtain the zero shear rate viscosity and any of the other functions, these methods are all equivalent. The issue, however, revolves aroimd the fact that some features that appear in the dynamic modulus disappear if the compliance is used as the function to represent the data and vice versa. Also, some measurements are more or less dominated by the viscosity contribution. As a result, some problems of misinterpretation of data could be averted if workers who prefer modulus representations would calculate the compliances. In addition, those who measure the compliance should calculate the moduli in order to provide the data in the format that is more common in the field because of the large number of commercial instruments that obtain dynamic moduli. The advent of modern software packages that make the interrelationships easily calculated makes this dispute seem to go away. The pathways to determine the different material functions, one from the other, are shown in Figure 6. 

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