234 Computational Modelling of Biomechanics and Biotribology
modulus of the collagen network. However, the formulation of collagen vis-
coelasticity is not necessary either, as long as the short-term brillar mod-
ulus is used. Therefore, only the uid-driven viscoelasticity needs to be
considered in compression, unless an accurate result for early relaxation or
creep is desired. It is not clear whether the intrinsic viscoelasticity of the PG
matrix is substantial. It does not seem to be indicated by suf cient data. It
would also be dif cult to prove experimentally because the collagen bre
network and PG matrix are always coupled in the physiological condition.
It is crucially important to understand how the external loadings are
passed ...