Fracture properties of green nano fibrous network with random and aligned fiber distribution: A hierarchical molecular dynamics and peridynamics approach

Abstract

• A hierarchical multi-scale approach is presented that bridging nano to micro scale to study the elastic and fracture parameters of nanofibrous network with random and aligned distribution of nanofibers. • At the atomistic scale, molecular dynamics simulations on freestanding pristine and silver-doped polylactic acid nanofibers are used to determine the energy release rate, elastic modulus, and Poisson's ratio which serve to inform PD at microscale. • At the microscale, peridynamics is used to assess crack propagation and fracture toughness for Mode I and Mode II in both aligned and randomly oriented fibrous networks. • The framework allows the investigation of the effects of fibre orientation and surface treatment on the elastic and fracture properties of the nanofibrous network. • A good agreement with the available experimental data confirms the applicability of the proposed method. Polylactic acid (PLA) nanofibrous networks have gained substantial interest across various engineering and scientific disciplines, such as tissue engineering, drug delivery, and filtration, due to their unique and multifunctional attributes, including biodegradability, tuneable mechanical properties, and surface functionality. However, predicting their mechanical behaviour remains challenging due to their structural complexity, multiscale features, and variability in material properties. This study presents a hierarchical approach to investigate the fracture phenomena in both aligned and randomly oriented nanofibrous networks by integrating atomistic modelling and non-local continuum mechanics, peridynamics. At the nanoscale, all-atom molecular dynamics simulations are employed to apply tensile loads to freestanding pristine and silver-doped PLA nanofibres, where key mechanical properties such as Young's modulus, Poisson's ratio, and critical energy release rate are determined using innovative approaches. A new method is introduced to seamlessly transfer data from molecular dynamics to peridynamics by ensuring the convergence of the tensile response of a single fiber in both frameworks. This nano to micro coupling technique is then utilised to examine the Young's modulus, fracture toughness of mode I and II, and crack propagation in PLA nanofibrous networks. The proposed framework can also incorporate the effects of surface coating and fiber arrangements on the measured properties. The current research paves the way for the development of stronger and more durable eco-friendly nanofibrous networks with optimised performance.

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