An atomic finite element model for biodegradable polymers. Part 1. Formulation of the finite elements

• We develop a new simulation technique for atomic analysis.
• Computational demands are much lower than MD.
• We adapt a molecular dynamics (MD) force field to enable static linear analysis.
• Atomic finite elements are formulated for each MD potential energy function.
• Crystalline and amorphous poly(lactide) atomic structures are analysed.

Molecular dynamics (MD) simulations are widely used to analyse materials at the atomic scale. However, MD has high computational demands, which may inhibit its use for simulations of structures involving large numbers of atoms such as amorphous polymer structures. An atomic-scale finite element method (AFEM) is presented in this study with significantly lower computational demands than MD. Due to the reduced computational demands, AFEM is suitable for the analysis of Young׳s modulus of amorphous polymer structures. This is of particular interest when studying the degradation of bioresorbable polymers, which is the topic of an accompanying paper. AFEM is derived from the inter-atomic potential energy functions of an MD force field. The nonlinear MD functions were adapted to enable static linear analysis. Finite element formulations were derived to represent interatomic potential energy functions between two, three and four atoms. Validation of the AFEM was conducted through its application to atomic structures for crystalline and amorphous poly(lactide).

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