# Viscoelastic Models: Analyzing Relaxation & Creep Data

• La82
In summary, the individual is seeking advice on whether to use the Prony series or the generalized Kelvin Voigt model to analyze relaxation and creep data for a solid polymer. They have found success using the Prony series for relaxation data, but are unsure if it is appropriate to use for creep data. Another individual suggests that as long as the deformations are small and the time scales are the same, the model fit for relaxation data should also apply to creep data.
La82
Hi everyone,

So I have a set of relaxation data and creep data for a solid polymer that I want to analyse. In the relaxation I use the Prony series derived from the generalized maxwell equation (incl a spring) and get a very nice fit. My question is if I should use the same to model the creep? Or should I use the generalized Kelvin Voigt?

I have applied the prony series to the creep data and can get a good fit, but I am a bit confused as to the validity of using this model on creep data.

Hope someone can help me with this,

Lonnie

The constitutive model is supposed to be independent of the specific deformation. I assume you are using a linear model valid for small deformations. Make sure that the deformations are small. The relaxation data is in shear? Any DMA shear data? That should help test the model to.

Getting back to your original question, if the time scales for the deformations are the same and the deformations are small, then the model fit to the relaxation data should also apply to the creep data.

## What is a viscoelastic model?

A viscoelastic model is a mathematical representation of the behavior of a material that exhibits both solid-like (elastic) and liquid-like (viscous) properties. These models are used to analyze and predict the relaxation and creep behavior of materials.

## What is relaxation data?

Relaxation data refers to the change in stress or strain over time in a viscoelastic material when subjected to a constant deformation. It is used to measure the material's ability to dissipate energy and return to its original state after being deformed.

## What is creep data?

Creep data refers to the change in strain over time in a viscoelastic material when subjected to a constant stress. It is used to measure the material's ability to deform under a constant load without breaking.

## What factors affect relaxation and creep behavior?

The relaxation and creep behavior of a material can be affected by a variety of factors, including temperature, load magnitude, and time. Other factors such as the material's composition, molecular structure, and external environment can also play a role.

## How are viscoelastic models used in industry?

Viscoelastic models are commonly used in industry to predict the behavior and performance of materials in various applications. This includes the design of products and structures, such as rubber seals, adhesives, and biomedical devices, as well as the development of new materials with specific viscoelastic properties.

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