Axial compressive stiffness of cylindrical,conical and looped carbon-tube nanosprings

By the classical method of strength of material,the deformation of carbon-tube nanosprings(CTNS), including cylindrical,conical and looped ones,under axial-compression,is analyzed,and a general formula for stiffness of CTNSs is obtained.In order to validate the formula,the stiffness for a cylindrical CTNS is calculated and compared with the corresponding experimental and FE(Finite element) results.It is shown that the present value of the stiffness is very close to both experimental and FE ones.