To use all functions of this page, please activate cookies in your browser.
my.chemeurope.com
With an accout for my.chemeurope.com you can always see everything at a glance – and you can configure your own website and individual newsletter.
 My watch list
 My saved searches
 My saved topics
 My newsletter
KelvinVoigt materialA KelvinVoigt 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 William Thomson, 1st Baron Kelvin and after German physicist Woldemar Voigt
Additional recommended knowledge
DefinitionThe KelvinVoigt model, also called the Voigt model, can be represented by a purely viscous damper and purely elastic spring connected in parallel as shown in the picture:
If we connect these two elements in series we get a model of a Maxwell material. Since the two components of the model are arranged in parallel, the strains in each component are identical:
Similarly, the total stress will be the sum of the stress in each component:
From these equations we get that in a KelvinVoigt material, stress σ, strain ε and their rates of change with respect to time t are governed by equations of the form: where E is a modulus of elasticity and η is the viscosity. The equation can be applied either to the shear stress or normal stress of a material. Effect of a sudden stressIf we suddenly apply some constant stress σ_{0} to KelvinVoigt material, then the deformations would approach the deformation for the pure elastic material σ_{0} / E with the difference decaying exponentially:
where t is time and the rate of relaxation λ is also the inverse of the relaxation time. The picture shows dependence of dimensionless deformation upon dimensionless time λt. The material is loaded by the stress at time t = 0 that is released at different dimensionless times If we would free the material at time t_{1}, then the elastic element would retard the material back until the deformation become zero. The retardation obeys the following equation:
Since all the deformation is reversible (though not suddenly) the KelvinVoigt material is a solid. The Voigt model predicts creep more realistically than the Maxwell model, since for while a Maxwell model predicts a linear relationship between strain and time, which is most often not the case. Alternatively, although the KelvinVoigt model is effective for predicting creep, it is not good at describing the relaxation behavior after the stress load is removed. Dynamic modulusThe complex dynamic modulus of the KelvinVoigt material would be: Thus, the real and imaginary components of the dynamic modulus are: Note that E_{1} is constant, while E_{2} is directly proportional to frequency (where the apparent viscosity, η, is the constant of proportionality). References
See alsoCategories: NonNewtonian fluids  Materials science 

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "KelvinVoigt_material". A list of authors is available in Wikipedia. 