Collapse analysis of nanofibres

Continuous nanofibres fabricated by the electrospinning technique have found increasing applications (e.g. nanofibre composites, nanofibre devices, bioengineering tissue scaffolding, etc). For a nanofibre network subjected to a small external perturbation, the fibre segments within the network may deflect and stick to each other under the condition that their surface adhesion energy overcomes the elastic strain energy induced by fibre bending. Therefore, this paper aims to study adhesion-induced nanofibre collapse and relevant criteria. A simple fibre collapse model was proposed, which is based on the contact of two deflected elastic filaments under surface adhesion. Four fundamental fibre collapse modes (i.e. fibre-flat substrate, parallel fibres, orthogonal fibres and fibres at arbitrary angle) were considered, and corresponding collapse criteria were determined in explicit forms. Effects of fibre elasticity, surface adhesion and fibre geometries on the collapse criterion were explored in a numerical manner. Results show that for a fibre segment pair at a relatively large angle, the critical distance to induce the fibre collapse is independent of the fibre radius. This distance is a function of the fibre aspect ratio and the material intrinsic length (γ/E, where γ is the surface energy and E is Young's modulus). The fibre collapse model developed in this study can be used as the theoretical basis for design and failure analysis of nanofibre networks and nanofibre devices, among others.