Resonance methods of measurement viscoelasticity of biological structures

Overview

Dynamic loading is typical for most biological structures. Consequently, mechanical behavior of biological structures cannot be fully described by static parameters and characteristics. Changes in deformation lead to energy losses, furthermore, energy losses are result of existence of viscose constituents in mechanical behavior in biological materials. Bodies in which losses of energy are not negligible belong to category of so called viscoleastic bodies. Viscoelasticity is property of bodies or material that exhibits both viscous and elastic behavior when deformed.

From the mathematical point of view, relationships between stresses and strains may be described by adequate differential equation. More practical approach is based on rheological models or, more recently, on determination of complex modules of elasticity, complex dynamic stiffness and mechanical impedance.

Availability of applicable methodology of measurement of viscoelasticity is essential for quantification of mechanical behavior of viscoelastic bodies. At present, methodology DMA (dynamic mechanical analysis) is applied for measurement of viscoelasticity in industry. The DMA is based on measurement of mechanical frequency characteristics. Methods based on RMA (resonance mechanical analysis) are designated for measurements in biomechanical and biomedical laboratories.

Key words:
Viscoelasticity; measurement; complex moduli; mechanical impedance;