Designing graphene-based nanofoams with nonlinear auxetic and   anisotropic mechanical properties under tension or compression
  In this study, the analysis of the mechanical response of realistic fullerene-nanotube nanotruss networks with face-centered cubic geometry is performed by using molecular dynamics with reactive potentials. In particular, the mechanical properties of these novel architectures are investigated in both compressive and tensile regimes, by straining along different directions a number of truss geometries. Our atomistic simulations reveal a similar behavior under tensile stress for all the samples. Conversely, under compressive regimes the emergence of a response that depends on the orientation of load is observed together with a peculiar local instability. Due to this instability, some of these nanotruss networks present a negative Poisson ratio in compression, like re-entrant foams. Finally, the performance of these nanotruss networks is analyzed with regards to their use as impact energy absorbers, finding properties outperforming materials traditionally used in these applications. 
Andrea Pedrielli, Simone Taioli, Giovanni Garberoglio, Nicola Pugno
cond-mat.mes-hall