Vinh Tu , Fredrik Larsson , Kenneth Runesson , Ralf Jänicke
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引用次数: 0
Abstract
This paper considers chemical diffusion in a Structural Battery Electrolyte (SBE) under the influence of finite deformation, which serves as a first step towards the more rigorous electro-chemically coupled modeling of deformation-dependent ionic transport in SBEs. The SBE is a porous (bicontinuous) microstructure consisting of a solid (polymer) skeleton, and pores filled with a liquid electrolyte. We present a variationally consistent computational homogenization scheme and exploit 3D-representation of the microstructure to compute the deformation-dependent effective mobility via direct upscaling in a two-step procedure (sequentially coupled approach). The pertinent RVE problem is established for the mechanical (equilibrium) problem under macro-scale deformation control, while adopting Neo-Hooke hyperelasticity for the fine-scale modeling of the solid skeleton. Thereby, the elastic moduli are calibrated based on experimental data for the effective response. Subsequently, Fickian diffusion, with a constant mobility in the liquid electrolyte is considered in the deformed pore space. Exploiting a pull-back to the reference configuration, we avoid remeshing while still incorporating the necessary pore space deformation. By adopting a suitable constitutive model for the fictitious solid in the pore space, we also prevent self-penetration of the solid skeleton during deformation, which mimics contact behavior without explicitly solving a computationally expensive contact problem involving contact search. Upon homogenizing the local ionic flux, we obtain the effective mobility pertaining to the macro-scale chemical potential gradient, while noting that the RVE-problem is linear in the chemical potential for a given macro-scale deformation gradient. The numerical results show that when the macro-scale loading is of compressive type, the pore volume is reduced and, as a direct consequence, the effective mobility becomes smaller. In essence, the framework can track the geometrically induced anisotropy of the RVE under mechanical loading, corresponding to a change in the computational domain for the transport problem, thereby influencing the ionic flux. E.g. for a bicontinuous SBE with 37% initial porosity and an externally applied macroscopic compression of 20% strain, we could observe up to 26% reduction in the effective mobility components.
期刊介绍:
The International Journal of Solids and Structures has as its objective the publication and dissemination of original research in Mechanics of Solids and Structures as a field of Applied Science and Engineering. It fosters thus the exchange of ideas among workers in different parts of the world and also among workers who emphasize different aspects of the foundations and applications of the field.
Standing as it does at the cross-roads of Materials Science, Life Sciences, Mathematics, Physics and Engineering Design, the Mechanics of Solids and Structures is experiencing considerable growth as a result of recent technological advances. The Journal, by providing an international medium of communication, is encouraging this growth and is encompassing all aspects of the field from the more classical problems of structural analysis to mechanics of solids continually interacting with other media and including fracture, flow, wave propagation, heat transfer, thermal effects in solids, optimum design methods, model analysis, structural topology and numerical techniques. Interest extends to both inorganic and organic solids and structures.