Microstuctural models of ligament and tendon elasticity and viscoelasticity
Dr Tom Shearer (University of Manchester)
Thursday 27th October, 2016 14:00-15:00 Maths 522
Ligaments and tendons are made of collagen fibres organised in a complex, hierarchical structure. Their main subunit is the fascicle, which consists of a large number of fibrils that exhibit varying levels of crimp. In this talk, I will discuss two microstructural models of the mechanical behaviour of ligaments and tendons. The first model is a non-linear elastic model, which is expected to be valid in the low strain-rate limit, where hysteresis is minimised. I will derive a new strain energy function for modelling ligaments and tendons based on the geometrical arrangement of their fibrils (which are assumed to be linear elastic), and will compare the ability of the new model to reproduce experimental data with that of the commonly-used Holzapfel-Gasser-Ogden (HGO) model. The second model is a viscoelastic model. By assuming that each fibril is linear viscoelastic, I will show that the non-linear viscoelasticity of ligaments and tendons may be due entirely to the geometrical arrangement of their fibrils. The viscoelastic model agrees well with experimental data on rat tail tendon, and can reproduce multiple data sets with a single set of constitutive parameters simply by changing the distribution of the fibril crimp lengths.