A note on the reduced creep function corresponding to the quasi-linear visco-elastic model proposed by Fung

For description of the visco-elastic behavior of soft biological tissues, Fung proposed a visco-elastic model formulated in terms of a relaxation function and corresponding relaxation spectrum. For the corresponding creep function, Fung proposed an expression which needs correction to obtain a consistent formulation. This creep function and the corresponding creep spectrum are derived in this note

Aortic valve histology and its relation with mechanics : preliminary report

Histological secitons of relaxed porcine aortic valves were studied from a mechanical point of view. The observations are combined into a tractable scheme of the tissue structure of the aortic valve. The valve leaflets can be regarded as an elastic meshwork, reinforced with stiff collagen bundles, showing an arrangement in one particular direction. The sinus walls consist of smooth muscle tissue, embedded in an elastic meshwork. The line of attachment of the leaflets to the sinus walls is constituted by the aortic ring, a crownlike fibrocartilaginous structure, containing large amounts of collagen fibres. This simple scheme of the tissue structure can be expected to provide important starting-points for both the interpretation of experimental results and the theoretical modelling of aortic valve mechanics and kinematics

The dynamics of a deformable body experiencing large displacements

The displacements are resolved into displacements due to deformation and displacements due to rigid body motion. The former are approximated with a linear combination of assumed displacement fields. D'Alembert's principle is used to derive the equations of motion. For this purpose, the rigid body displacements and the displacements due to deformation have to be independent. Commonly employed conditions for achieving this are reviewed. Some conditions lead to simpler equations of motion and a sparser mass matrix, resulting in CPU time savings when used in a multibody program. This is illustrated with a uniform beam and a crank-slider mechanis