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Mechanical response of the carbon nanotube bundle to uniaxial and biaxial lateral compression followed by unloading is modeled under plane strain conditions. The chain model with a reduced number of degrees of freedom is employed with high efficiency. During loading, two critical values of strain are detected. Firstly, period doubling is observed as a result of the second order phase transition, and at higher compressive strain, the first order phase transition takes place when carbon nanotubes start to collapse. The loading-unloading stress-strain curves exhibit a hysteresis loop and, upon unloading, the structure returns to its initial form with no residual strain. This behavior of the nanotube bundle can be employed for the design of an elastic damper.

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Bulk carbon nanomaterials, which open prospects for the development of a new generation of supercapacitors, are actively investigated for recent years, but their mechanical properties and structure remain poorly understood. In connection with this fact, the influence of the hydrostatic and uniaxial com pression on mechanical properties and structure of three bulk nanomaterials consisting of (i) bent graphene flakes, (ii) short carbon nanotubes, and (iii) fullerenes C 240 are investigated by the molecular dynamics method. It is shown that the strength of the material and its stability to graphitization depend on its constit uent structural units. At large degrees of deformation, the material consisting of bent graphene sheets has the highest strength, whereas at the material density lower than 2.5 g/cm 3 , the highest strength is observed in the nanomaterial consisting of fullerene molecules. The differences in mechanical properties of the materials under consideration are explained by their structural features.

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