About Some Mechanical Properties

To judge if a particular kind of material is a good fit for some purposes, the criterion are based on its mechanical properties, which allow us to know how far it could go when it’s in the position.

I’ve talked about how strong graphene is compared to A36 steel. We could find some properties of it from Graphenea (De La Fuenta). Unflawed graphene has a modulus of elasticity (Young’s modulus) of 0.5 Tpa, meaning when graphene experience a stress and is deformed elastically, the deformation or strain could be estimated as the stress divided by 0.5Tpa, which is extremely small! As you could imagine, the less it deforms, the stronger it is. On the other hand, graphene has the tensile strength as 130Gpa. Tensile strength indicates the maximum stress one can afford. If the material continues to be under this stress, it would fail eventually.

There are also some other features, which are explained in Callister and Rethwisch’s work (2008).

“Hardness is a measure of the resistance to localized plastic deformation.” If two materials crash into each other, the harder one leaves indentation on the other. (A bar of chocolate is harder than marshmallows.) The softer one is, the deeper the indentation it is. The hardness is almost always proportional to the tensile strength.

“Ductility … is a measure of the degree of plastic deformation that has been sustained at fracture.” If a material is brittle, it is not capable to sustain much when it deforms before it becomes fractures. (Chocolate is more brittle than marshmallows.)

“Toughness … is a measure of the ability of a material to absorb energy up to fracture.” One is tough must be considered to have good strength and ductility. Thus spider silk could be a brilliant example for toughness.

 

Reference

Callister, W. D., & Rethwisch, D. G. (2008). Fundamentals of materials science and engineering: An integrated approach. Hoboken,   NJ: John Wiley & Sons.

De La Fuente, Jesus. Graphene Properties. Retrieved from:

http://www.graphenea.com/pages/graphene-properties#.U52vFPmsiSo