Hi Chuanyun ,

You already introduced the answer....... "Buckling",

i thought it could be compared with a case of a fabric or a rope, a tensile test is possible but compression is non practical.

you cannot get results from non outstanding body

Hi Heider,

so do you think the elastic slope of CNT before buckling during compression is similar to the counterpart in the tensile test? thx!

Hi Chuanyun,

practically it seems to be impossible to get outstanding single CNT able to bear compression forces. But,

theoretically we can suppose these situations possible and make a required modelling to calculate values of intended properties. In this case the determined elastic slope of CNT during compression will substantially differs from the counterpart in the tensile test, not as disagreement between theoretical and practical parts,

but because the response of covalent bonds (bonding carbon) is not same in both cases,

and this is why buckling happens.

Regards

Hi Heider,

so the CNTs are tensile-compression asymmetrical and this feature stems from the specific bonding between carbon atoms in CNTs, is it correct? Do you have any supporting papers or statements? Thx!

Best!

In my opinion at your (purely mechanical) approach there is no difference that to investigate usual fibers with a diameter of 6 microns, or nanotubes with a diameter of 0,001 microns, and such models are well developed. It will be natural at compression at first the line section, and then stability loss( buckling ). But you haven't written how nanotubes in the directions are distributed if it is isotropic, then can not reach loss of stability. And in case of the unidirectional tubes (fibers) it is possible to assume that loss of stability( buckling ) will happen at big loadings as, in a stability loss condition the module of fiber undertakes with a root square, and the module of elasticity of tubes about 1000 GPA and above than at fibers (200 - 400 GPA).

Hi Chuanyun,

please read article entitled "Mechanics of carbon nanotubes" by Dong Qian, Gregory J Wagner, and Wing Kam Liu,

in addition to its precious contents, you'll find inside it a specific references about your subject.

regards