Understanding Viscoelasticity - Questions Answered

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In summary, viscoelasticity refers to the behavior of materials that exhibit both elastic and viscous properties. In elastic materials, deformation increases upon application of constant stress and remains constant until the stress is removed, while in viscoelastic materials, the deformation continues to increase. When the force is removed, the deformation reduces but the material is induced with a permanent deformation. An ideal elastic material returns to its original configuration once the loading is removed. In contrast, the relaxation time for a Newtonian fluid is very short, resulting in a quick decline to zero stress when strain is applied.
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knoble
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I always get confused while trying to understand viscoelasticity.

As far as I understand,
- In Elastic materials, deformation increases upon application of constant stress and remains constant until the stress/force is removed. Upon removal of force, the deformation reduces and the material attains its original postition.
- In Viscoelastic materials, deformation increases with stress, continues to increase (not constant in this case). When the force is removed, the deformation reduces but the material is induced with a permanent deformation.

Question:
- Dont elastic materials deform permanently upon failure? (or is that if the constant stress applied is lesser than the failure limit, the material does not fail and the deformation is constant)
- Since viscoelastic material also behave similar to Newtonian fluid, why does the stress increase with application of strain and then quickly decline to zero in Newtonian fluid?

It would be great if someone can explain this clearly.

Thanks!
NK
 
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  • #2
knoble said:
Question:
- Dont elastic materials deform permanently upon failure? (or is that if the constant stress applied is lesser than the failure limit, the material does not fail and the deformation is constant)
An ideal elastic material is defined as one that returns to its original configuration once the loading is removed.
- Since viscoelastic material also behave similar to Newtonian fluid, why does the stress increase with application of strain and then quickly decline to zero in Newtonian fluid?

Because the relaxation time for a Newtonian fluid is very short (actually, it's zero in the perfectly Newtonian limit).

Chet
 

1. What is viscoelasticity?

Viscoelasticity is the property of a material to exhibit both viscous and elastic behaviors when subjected to stress or strain. This means that the material can both resist deformation and flow or relax over time.

2. What are some examples of viscoelastic materials?

Some common examples of viscoelastic materials include polymers, rubber, and biological tissues such as skin and cartilage. These materials are often used in everyday products such as tires, gels, and adhesives.

3. How does viscoelasticity affect the behavior of materials?

The presence of viscoelasticity in a material can significantly affect its mechanical properties, such as stiffness, strength, and creep. It can also impact the material's response to different loading conditions, such as tension, compression, or shear.

4. What factors influence the viscoelastic behavior of materials?

The viscoelastic behavior of a material is influenced by several factors, including temperature, strain rate, and the duration of loading. Additionally, the chemical and physical structure of the material, including its molecular weight, composition, and cross-linking, can also affect its viscoelastic properties.

5. Why is understanding viscoelasticity important?

Understanding viscoelasticity is crucial for many applications, such as in the design of materials and structures. It allows scientists and engineers to predict how a material will behave under different loading conditions and make informed decisions about its use. Additionally, viscoelasticity plays a significant role in various fields, including biomechanics, materials science, and manufacturing processes.

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