ABSTRACT
This chapter discusses the properties and behavior of Hookean solids and Newtonian fluids: materials that are special cases, on either extreme of the spectrum of material behavior. These materials and most applications fit our favorite simplifying assumptions, nicely. Biomaterials may be natural or artificial. Scientific interest in biomaterials is not an exclusively modern phenomenon: ancient technology relied on horn, tendon, and various woods and fibers. The properties, microstructure, and behavior of natural biomaterials change in response to the physiological environment. This makes determining decisive experimental results or developing detailed constitutive models very difficult. The bulk of elastomechanical testing of natural biomaterials has been conducted in vitro in an experimental simulacrum of in vivo conditions, including thermal conditions and ionic concentrations which affect smooth muscle activity. For viscoelastic materials, both how much they deform and how fast they deform are important. Many, biomaterials exhibit some degree of viscoelasticity. The two primary characteristics of viscoelastic behavior are creep and stress relaxation.
