Modeling microscale instabilities in compressed carbon nanotube bundles using multistable spring models

We formulate in situ parameter identification techniques for multistable spring models of compressed CNT bundles, which capture the sequential buckling through the height of the bundle, as well as the overall mechanical response. The proposed techniques are validated against a SEM-assisted compression experiment on a CNT pillar [1]. Using multi-spring models, we propose a 'microscopic' identification technique based on the determination of stress–strain curves of vertical segments of the tested structure (featuring few micron height). We show that the in situ identified models can effectively reproduce the experimentally-observed stress–strain response (single-spring models), and strain localization effects (multi-spring model), within a simple 1D framework.