Auxetic MaterialsAuxetic Materials

by:by:

Zahra Elkassabgi Zahra Elkassabgi

What’s Poisson Ratio?What’s Poisson Ratio?

Ratio of axial and lateral strainsRatio of axial and lateral strains

Formulated so most materials with Formulated so most materials with positive valuepositive value

ν= ν= -Єx -Єx = = -Єy-Єy

Єz ЄzЄz Єz

What are auxetic materials and What are auxetic materials and their properties?their properties?

Materials with a negative Poisson ValueMaterials with a negative Poisson Value

Density may vary from one-trillionth the Density may vary from one-trillionth the density of air or 100 billion times airdensity of air or 100 billion times air

Formed -460*F or 10,000+ heat of white Formed -460*F or 10,000+ heat of white dwarf starsdwarf stars

Auxetic v. Normal materialsAuxetic v. Normal materials

Auxetic Auxetic materialsmaterials

Larger when stretchedLarger when stretched

Smaller when Smaller when compressedcompressed

Normal materialsNormal materials

Smaller when Smaller when stretchedstretched

Larger when Larger when compressedcompressed

Applications of Auxetic Applications of Auxetic materialsmaterials

NatureNature

Neutron starsNeutron stars

White dwarfWhite dwarf

Skin of a catSkin of a cat

ManufacturedManufactured

(still under research)(still under research)

Artificial musclesArtificial muscles

Artificial arteriesArtificial arteries

Structural Structural connectorsconnectors

Advantages of auxetic Advantages of auxetic materialsmaterials

Increased shear stiffnessIncreased shear stiffness

Increased plane strain fracture toughnessIncreased plane strain fracture toughness

Increased indentation resistanceIncreased indentation resistance

Superior to conventional materials for Superior to conventional materials for many practical applicationsmany practical applications

ReferencesReferences http://www.dallasnews.com/sharedconntent/dallas/healthsciences/storieshttp://www.dallasnews.com/sharedconntent/dallas/healthsciences/stories

http://silver.neep.wisc.edu/~lakes/PoissonStru.htmlhttp://silver.neep.wisc.edu/~lakes/PoissonStru.html

http://silver.neep.wisc.edu/~lakes/PoissonEnd.htmlhttp://silver.neep.wisc.edu/~lakes/PoissonEnd.html

http://silver.neep.wisc.edu/~lakes/Poisson.htmlhttp://silver.neep.wisc.edu/~lakes/Poisson.html

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