ELASTIC MATERIALS: TYPES, CHARACTERISTICS AND EXAMPLES - CHEMISTRY - 2025

The elastic materials are those materials which have the ability to resist an influence or distorting or deforming force, and then return to its original shape and size when the same force is removed.

Linear elasticity is widely used in the design and analysis of structures such as beams, plates, and sheets. Elastic materials are of great importance to society, since many of them are used to make clothes, tires, automotive parts, etc.

Elastic materials characteristics

When an elastic material is deformed by an external force, it experiences an internal resistance to deformation and restores it to its original state if the external force is no longer applied.

To some extent, most solid materials exhibit elastic behavior, but there is a limit to the magnitude of the force and the attendant deformation within this elastic recovery.

A material is considered elastic if it can be stretched up to 300% of its original length. For this reason, there is an elastic limit, which is the greatest force or tension per unit area of ​​a solid material that it can withstand in the event of permanent deformation.

For these materials, the yield point marks the end of their elastic behavior and the beginning of their plastic behavior. For weaker materials, stress on their yield point results in their fracture.

The elasticity limit depends on the type of solid considered. For example, a metal bar can be elastically extended up to 1% of its original length.

However, fragments of certain rubbery materials can experience extensions of up to 1000%. The elastic properties of most intent solids tend to fall between these two extremes.

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Types of elastic materials

Models of elastic materials type Cauchy

In physics, a Cauchy elastic material is one in which the stress / tension of each point is determined only by the current state of deformation with respect to an arbitrary reference configuration. This type of material is also called simple elastic material.

Based on this definition, the stress in a simple elastic material does not depend on the strain path, the strain history, or the time it takes to achieve that strain.

This definition also implies that the constitutive equations are spatially local. This means that stress is only affected by the state of the deformations in a neighborhood close to the point in question.

It also implies that the force of a body (such as gravity) and the forces of inertia cannot affect the properties of the material.

Simple elastic materials are mathematical abstractions, and no real material fits this definition perfectly.

However, many elastic materials of practical interest, such as iron, plastic, wood, and concrete, can be assumed to be simple elastic materials for stress analysis purposes.

Although the stress of simple elastic materials depends only on the state of deformation, the work done by stress / stress can depend on the deformation path.

Therefore, a simple elastic material has a non-conservative structure and stress cannot be derived from a scaled elastic potential function. In this sense, materials that are conservative are called hyperelastic.

Hypoelastic materials

These elastic materials are those that have a constitutive equation independent of the finite stress measurements except in the linear case.

Hypoelastic material models are different from hyperelastic material models or simple elastic material models in that, except in particular circumstances, they cannot be derived from a function of deformation energy density (FDED).

A hypoelastic material can be rigorously defined as one that is modeled using a constitutive equation that satisfies these two criteria:

• The tension tensor ō at time t depends only on the order in which the body has occupied its past configurations, but not on the period in which these past configurations were traversed.

As a special case, this criterion includes a simple elastic material, in which the current stress depends only on the current configuration rather than the history of past configurations.

• There is a tensor-function with value G such that ō = G (ō, L) in which ō is the span of the material's stress tensor and L is the space velocity gradient tensor.

Hyperelastic materials

These materials are also called Green's elastic materials. They are a type of constitutive equation for ideally elastic materials for which the relationship between stress is derived from a strain energy density function. These materials are a special case of simple elastic materials.

For many materials, linear elastic models do not correctly describe the observed behavior of the material.

The most common example of this class of material is rubber, whose stress-tension relationship can be defined as non-linear, elastic, isotropic, incomprehensible, and generally independent of its stress ratio.

Hyperelasticity provides a way to model the stress-tension behavior of such materials.

The behavior of empty and vulcanized elastomers often conform to the hyperelastic ideal. Filled elastomers, polymeric foams, and biological tissues are also modeled with hyperelastic idealization in mind.

Hyperelastic material models are regularly used to represent high-strain behavior in materials.

They are usually used to model full and empty elastomer and mechanical behavior.

Examples of elastic materials

1- Natural rubber

2- Spandex or lycra

3- Butyl rubber (PIB)

4- Fluoroelastomer

5- Elastomers

6- Ethylene-propylene rubber (EPR)

7- Resilin

8- Styrene-butadiene rubber (SBR)

9- Chloroprene

10- Elastin

11- Rubber epichlorohydrin

12- Nylon

Nylon

13- Terpene

14- Isoprene rubber

15- Poilbutadiene

16- Nitrile rubber

17- Stretch vinyl

18- Thermoplastic elastomer

19- Silicone rubber

20- Ethylene-propylene-diene rubber (EPDM)

21- Ethylvinylacetate (EVA or foamy rubber)

22- Halogenized butyl rubbers (CIIR, BIIR)

23- Neoprene

References

1. Types of elastic materials. Recovered from leaf.tv.
2. Cauchy elastic material. Recovered from wikipedia.org.
3. Elastic materials examples (2017) Recovered from quora.com.
4. How to choose an hyperelastic material (2017) Recovered from simscale.com
5. Hyperlestic material. Recovered from wikipedia.org.