Applications of viscoelastic clock models in biomechanics
The viscoelastic response of inert polymers, with respect to stress relaxation and creep, can be sped up by increasing their temperature or slowed down by decreasing their temperature. An explanation for such behavior is the existence of an internal clock whose speed relative to the laboratory clock is affected by temperature. It is assumed that the viscoelastic response of biological tissue can be affected by a biochemical factor, such as a hormone or medication, in a manner similar to that of temperature for an inert polymer. The concept of the intrinsic clock is introduced into the constitutive theory for the viscoelastic response of biological materials. Two examples are presented that illustrate the implications of a biochemically dependent internal clock: (1) cervical softening during birth due to a hormone release, (2) blood vessel dilation induced by medication.