# It would take an elephant, balanced on a pencil, to break through a sheet of graphene the thickness of Cling Film

I'm currently doing some work on a presentation about graphene, and have come across numerous articles which claim something along the lines of

It would take an elephant, balanced on a pencil, to break through a sheet of graphene the thickness of Saran Wrap / Cling Film.

My question is, is there any proof / calculations to back up this claim? Every article I come across seems to be very similar and I cannot find the original source which might contain proof, or a link the relevant paper/study

Sources

-

I think you are looking for something like this:

We measured the elastic properties and intrinsic breaking strength of free-standing monolayer graphene membranes by nanoindentation in an atomic force microscope. The force-displacement behavior is interpreted within a framework of nonlinear elastic stress-strain response, and yields second- and third-order elastic stiffnesses of 340 newtons per meter (N m–1) and –690 Nm–1, respectively. The breaking strength is 42 N m–1 and represents the intrinsic strength of a defect-free sheet. These quantities correspond to a Young's modulus of E = 1.0 terapascals, third-order elastic stiffness of D = –2.0 terapascals, and intrinsic strength of σint = 130 gigapascals for bulk graphite. These experiments establish graphene as the strongest material ever measured, and show that atomically perfect nanoscale materials can be mechanically tested to deformations well beyond the linear regime.

So when Young's modulus of monolayer graphene is around $10^{12} \;\textrm{Pa}$, a back of the napkin estimate suggests that over a surface of $1 \;\textrm{mm}$ graphene can easily withstand $10^6 \;\textrm{N}$, which looks like a nice guess for an elephant several elephants to me :)

-
$10^6~\text{N}$? Isn't that more like a whole herd? –  Glen The Udderboat Apr 10 '13 at 16:59
Well, can we agree on somewhere around $\mathcal{O}(10)$? –  Wojciech Morawiec Apr 10 '13 at 17:02
+1 Sure, that's what I said: a herd. :) –  Glen The Udderboat Apr 10 '13 at 17:14