The Elastic materials Are those materials that have the ability to resist a distorting or deforming influence or force, and then return to their 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 spare parts, etc.
Characteristics of elastic materials
When an elastic material is deformed with an external force, it experiences an internal resistance to the deformation and restores it to its original state if the external force is no longer applied.
To a certain extent, most solid materials exhibit elastic behavior, but there is a limit of the magnitude of the force and the accompanying deformation within this elastic recovery.
A material is considered as 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 can withstand permanent deformation.
For these materials, the elasticity limit marks the end of their elastic behavior and the beginning of their plastic behavior. For weaker materials, the stress or stress on its elasticity limit results in its fracture.
The elasticity limit depends on the type of solid considered. For example, a metal bar can be extended elastically up to 1% of its original length.
However, fragments of certain gummy materials may undergo extensions of up to 1000%. The elastic properties of most solid intentions tend to fall between these two extremes.
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Types of elastic materials
Models of elastic materials Cauchy type
In physics, a Cauchy elastic material is one in which the stress / tension of each point is determined only by the current deformation state with respect to an arbitrary reference configuration. This type of materials is also called simple elastic material.
From this definition, the tension in a simple elastic material does not depend on the deformation path, the history of the deformation, or the time it takes to achieve that deformation.
This definition also implies that the constitutive equations are spatially local. This means that stress alone is 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 inertial forces can not 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 as simple elastic materials for stress analysis purposes.
Although the stress of the simple elastic materials depends only on the deformation state, the stress / stress work may depend on the deformation path.
Therefore, a simple elastic material has a non-conservative structure and the stress can not be derived from a scaled potential elastic 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 finite stress measurements except in the linear case.
The models of hypoelastic materials are different from the models of hyperelastic materials or simple elastic materials since, except in particular circumstances, they can not be derived from a deformation energy density (FDED) function.
A hypoelastic material can be rigorously defined as one that is modeled using a constitutive equation that satisfies these two criteria:
- The tensioning tensioner or To the time T Depends only on the order in which the body has occupied its past configurations, but not in the period in which these past configurations were crossed.
As a special case, this criterion includes a simple elastic material, in which the current voltage depends only on the current configuration rather than the history of the past configurations.
- There is a tensor function with value G so that or G ( or , L ) in which or Is the lapse of the tensor tension of the material and L Be the spatial velocity gradient tensor.
Hyperelastic materials
These materials are also called Green elastic materials. They are a type of constitutive equation for ideally elastic materials for which the relationship between stress is derived from a function of strain energy density. 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 kind of material is rubber, whose stress-strain relationship can be defined as non-linear, elastic, isotropic, incomprehensible and generally independent of its stress ratio.
Hyperelasticity provides a way of modeling the stress-tension behavior of such materials.
The behavior of empty and vulcanized elastomers often conform to the hyperelastic ideal. Full elastomers, polymer foams and biological tissues are also modeled with hyperelastic idealization in mind.
The models of hyperelastic materials are regularly used to represent a behavior of great deformation in the materials.
They are usually used to model mechanical behaviors and empty and full elastomers.
Examples of elastic materials
1- Natural gum
2- Spandex or lycra
Butyl Rubber (GDP)
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- Vinyl stretch
18- Thermoplastic elastomer
19- Silicone rubber
20- Ethylene-propylene-diene rubber (EPDM)
21- Ethylvinylacetate (EVA or foamy gum)
22- Halogenated butyl rubbers (CIIR, BIIR)
23- Neoprene
References
- Types of elastic materials. Retrieved from leaf.tv.
- Cauchy elastic material. Retrieved from wikipedia.org.
- Elastic materials examples (2017) Recovered from quora.com.
- How to choose an hyperelastic material (2017) Retrieved from simscale.com
- Hyperlestic material. Retrieved from wikipedia.org.