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Title: The viscoelastic behaviour of tendon
Author: Hooley, C. J.
ISNI:       0000 0001 3581 3202
Awarding Body: University of Oxford
Current Institution: University of Oxford
Date of Award: 1977
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The viscoelastic deformation of tendon has been studied in the 'toe' and 'linear' regions of the stress-strain curve. The extent to which the behaviour of thie material can be considered to be linear viscoelastic has been determined. It was found that the tendon exhibited non-linear visccolastic behaviour in both the 'toe' and 'linear' regions and the observed non-linearity was in contrast to that found for synthetic polymeric solids. The apparent activation energy, ΔHa, of the viscoelastic deformation process of tendon was determined by the temperature change (or T-jump) technique. A gradual transition was observed from the value of ΔEa = 12 kcal/mol in the 'toe' region to ΔHa = 32 kcal/mol in the 'linear' region in creep, recovery and stress relaxation experiments for a variety of tendon specimens. These values indicated that the viscoelastic mechanism of tendon deformation was one of shear of the mucopolysaccharide gel in between the collagen ribbons in the 'toe' region followed by fibrillar extension in the 'linear' region. A theoretical model based on this hypothesis and the assumptions of linear viscoelasticity was developed to explain the observed viscoelastic behaviour of tendon, using the normal viscoelastic parameters of the constituents of the tendon, the structural constants of the material and the appropriate form for the retardation spectrum. Excellent agreement between experiment and theory was found for a variety of experimental circumstances. A critical examination of the T-jump experiment was made. Generalised non-isothermal linear viscoelastic equations in creep were developed and the validity of these equations for the case of a ramp temperature change was tested on a specimen of poly(methylmethacrylate). The predicted increase in the experimentally obtained value of ΔHa was observed as the duration of the ramp temperature change increased. For the case of the instantaneous temperature change (T-jump) experiment, these equations were used, together with an appropriate form for the retardation spectrum, (either a box or a wedge distribution) to predict the creep rate dependence on time. Excellent fit of the creep rate data for tendon was obtained with these equations. Using a box distribution for the spectrum of retardation times in these equations, it was shown that the effect of bT on the creep rate behaviour could be neglected under most experimental circumstances.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available