Simulating Axial Force at the Substrate of Growing CNT Forests

A time-resolved carbon nanotube (CNT) forest synthesis model is used to examine the mechanical interactions of actively growing CNT forests. Discrete CNTs in the forest are modeled using linear elastic Euler-Bernoulli beam elements with three degrees of freedom at each node which corresponds to axial displacement, transverse displacement and rotation. The van der Waals force between adjacent CNTs is modeled as linear elastic spring elements and act to locally bond adjacent CNTs in contact. Special consideration is given to the axial forces that arise at the substrate of growing CNTs during the forest growth. While reaction forces are distributed in a spatiotemporal manner, we observe that reaction forces for the slowest growing CNTs are greatest, and in tension, while the fastest growing CNTs experience compressive reaction forces at the substrate.