Memorias de investigación
Communications at congresses:
i-Rheo GT: Transforming from Time to Frequency Domain without Artefacts

Research Areas
  • Mechanical aeronautics and naval engineering

?The nature of matter is to be found in the structure and motion of its constituent building blocks, and the dynamics is contained in the solution to the N-body problem. Given that the classical N-body problem lacks a general analytical solution, the only path open is the numerical one? [1]. In the field of rheology, it has been shown that the mechanical properties of (complex) materials are governed by the ensemble of inter- and intra-molecular interactions occurring at different time- and length-scales. This indeed is a classical N-body problem, for which a full analytical solution is still yearned. However, despite the multitude and the complexity of molecular interactions, rheologists have successfully drawn ?simplistic? representations of materials' topology that have substantially reduced the number of variables required to educe the materials' linear viscoelastic (LVE) properties by means of computer-aided numerical simulations. Nevertheless, despite their effectiveness in interpreting many experimental results, coarse-grained models lack of microscopic interpretations of molecular dynamics (MD) because of their inherent discrete nature. For this reason and concurrently with the continuous development of powerful central processing units and graphics processing units, rheologists have been encouraged to embark on MD simulations based on atomistic models. In this regard, we have developed a new rheological ?tool? to evaluate the materials? LVE properties over the widest range of experimentally accessible frequencies from MD simulations, without the need of preconceived models. This is achieved by evaluating the Fourier transforms of raw simulation data describing the temporal behaviour of the shear relaxation modulus (G(t)) by means of the analytical method introduced by Tassieri et al. [2]. The latter has been implemented into a new open access executable named ?i-Rheo GT? and its effectiveness has been corroborated both by analysing the dynamic response of model systems and by direct comparison with both bulk-rheology experimental data and coarse-grained molecular dynamics simulations data transformed via a generalised Maxwell model. Moreover, we fully exploit the results of previous rheological studies [3], and we demonstrate that, when i-Rheo GT is adopted to analyse the results obtained from atomistic MD simulations, it offers the opportunity to gain new insights into the materials' LVE properties, especially at highfrequencies (i.e., in the glassy region and above), where conventional tools struggle to interpret the data and MD simulations actually provide their most statistically accurate predictions of G(t).
Physical Aspects of Polymer Science 2019
Lincoln, Reino Unido
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Research Group, Departaments and Institutes related
  • Creador: Grupo de Investigación: Polímeros, Caracterización y Aplicaciones
  • Departamento: Ingeniería Química Industrial y del Medio Ambiente