What are viscoelastic models?
Viscoelastic behavior has elastic and viscous components modeled as linear combinations of springs and dashpots, respectively. Each model differs in the arrangement of these elements, and all of these viscoelastic models can be equivalently modeled as electrical circuits.
What does Maxwell model represent?
The Maxwell model represents a material with a linear Hookean spring connected in series with a Newtonian dashpot [13]. Because of two elements, the spring and the dashpot are subject to the same stress (σ = σs = σd), the model is also known as an iso-stress model (Fig.
What is the major difference between Kelvin Voight model and Maxwell’s model of viscoelasticity?
In the Maxwell model, both the spring and the dashpot are subjected to the same stress, but each element has an independent strain. In the Kelvin-Voigt model, both the spring and the dashpot are subjected to the same strain but each element has independent stress (Fig. 6.5).
What is meant by Linear viscoelasticity?
Linear viscoelasticity is a theory describing the behaviour of such ideal materials. Linear viscoelasticity is a reasonable approximation to the time-dependent behaviour of polymers, and metals and ceramics at relatively low temperatures and under relatively low stress.
Why is rubber viscoelastic?
Most rubber is produced from crosslinkable high molecular weight linear polymers with low glass temperatures [1 6]. They are viscoelastic by virtue of their time-dependent mechanical response, which reflects the sluggish configurational changes of the molecules.
Is human skin viscoelastic?
Skin is the primary interface between health care providers and patients and is assessed clinically to predict physiological stability or instability. The biomechanical properties of human skin, most notably elasticity and viscoelasticity, are critical to its protective function.
What is the Zener model?
The standard linear solid (SLS), also known as the Zener model, is a method of modeling the behavior of a viscoelastic material using a linear combination of springs and dashpots to represent elastic and viscous components, respectively. Often, the simpler Maxwell model and the Kelvin–Voigt model are used.
What is Maxwell time?
For typical values for the mantle (η ≈ 1021 Pa s and µ ≈ 1011 Pa), the Maxwell time is O(103) years, so on geological timescales, the mantle behaves as a viscous fluid. The Maxwell time for the lithosphere is much larger, and elasticity cannot always be ignored.
Is rubber a viscoelastic material?
Rubber is the most notable example of a polymer which exhibits viscoelastic properties. At a molecular level, rubber is formed of many polymer chains, the arrangement of which giving rise to its useful properties. The added material then forms additional cross links between polymer chains.
What makes skin viscoelastic?
Hyaluronic acid absorbs water, forming a thick gel that impedes the bulk flow of fluid and creates hydrostatic pressure and skin turgor; the hydrostatic pressure resists compressive forces, protects the solid structures of the skin, and contributes to the viscoelastic behaviors of the skin.
Which is the outermost layer of the skin?
epidermis
The epidermis is the thin outer layer of the skin. It consists of 2 primary types of cells: Keratinocytes. Keratinocytes comprise about 90% of the epidermis and are responsible for its structure and barrier functions.
How does a Dashpot work?
A dashpot is a common component in a door closer to prevent it from slamming shut. A spring applies force to close the door, which the dashpot offsets by forcing fluid to flow through an orifice, often adjustable, between reservoirs, which slows the motion of the door.
Which is the best model for a viscoelastic material?
The Kelvin model is a Maxwell model in parallel with an elastic element. This is also sometimes called the Standard Linear Model. The Kelvin model has properties of both the Maxwell and Voigt models. Most real viscoelastic materials exhibit behavior that are best described by the Kelvin model.
What happens to the viscosity of the Kelvin Voigt model?
Let us suppose that at low temperatures the “Maxwell viscosity”, η M, is very high – a material is “frozen” – and it is possible to neglect deformations of this element. Then, the model under discussion presents a solid-like behavior due to the spring G M. With temperatures increasing, viscosity, η M, decreases and relaxation becomes possible.
When is viscoelasticity represented by a Volterra equation?
Linear viscoelasticity is when the function is separable in both creep response and load. All linear viscoelastic models can be represented by a Volterra equation connecting stress and strain :
Who was the Kelvin Voigt material named after?
Kelvin–Voigt material. A Kelvin–Voigt material, also called a Voigt material, is a viscoelastic material having the properties both of elasticity and viscosity. It is named after the British physicist and engineer Lord Kelvin and after German physicist Woldemar Voigt.