| 1. |
- Carlstedt, David, 1984, et al.
(författare)
-
Electro-chemo-mechanically coupled computational modelling of structural batteries
- 2020
-
Ingår i: Multifunctional Materials. - : IOP Publishing. - 2399-7532. ; 3:4
-
Tidskriftsartikel (refereegranskat)abstract
- Structural batteries are multifunctional composites that combine load-bearing capacity with electro-chemical energy storage capability. The laminated architecture is considered in this paper, whereby restriction is made to a so called half-cell in order to focus on the main characteristics and provide a computational tool for future parameter studies. A thermodynamically consistent modelling approach is exploited for the relevant electro-chemo-mechanical system. We consider effects of lithium insertion in the carbon fibres, leading to insertion strains, while assuming transverse isotropy. Further, stress-assisted ionic transport is accounted for in addition to standard diffusion and migration. The relevant space-variational problems that result from time discretisation are established and evaluated in some detail. The proposed model framework is applied to a generic/idealized material representation to demonstrate its functionality and the importance of accounting for the electro-chemo-mechanical coupling effects. As a proof of concept, the numerical studies reveal that it is vital to account for two-way coupling in order to predict the multifunctional (i.e. combined electro-chemo-mechanical) performance of structural batteries.
|
|
| 2. |
- Carlstedt, David, 1984, et al.
(författare)
-
Unit cells for multiphysics modelling of structural battery composites
- 2019
-
Ingår i: ICCM International Conferences on Composite Materials. ; 2019-August
-
Konferensbidrag (refereegranskat)abstract
- To predict the multifunctional performance of structural battery composites, multiple physical phenomena need to be studied simultaneously. Hence, multiphysics models are needed to evaluate the complete performance of this composite material. In this study the coupled analysis for multiphysics modelling of structural battery composites is presented and modelling strategies and unit cell designs are discussed with respect to the different physical models. Furthermore, FE-models are setup in the commercial Finite Element (FE) software COMSOL to study if existing physics-based modelling techniques and homogenization schemes for conventional lithium ion batteries can be used to describe the electrochemical behaviour of structural battery composites. To predict the microscopic behaviour, the local variation of the mass and charge concentrations need to be accounted for. Hence, refined models with appropriate boundary conditions are needed to capture the microscopic conditions inside the material. The numerical results demonstrate that conventional physics-based 1D battery models and homogenization schemes based on porous media theory can be used to predict the macroscopic electrical behaviour of the fibrous structural battery. For future work electrochemical experiments on battery cell level are planned to validate the numerical results.
|
|
| 3. |
- Svahn, Per-Ola, 1965, et al.
(författare)
-
Discrete crack modelling in a new X-FEM format with emphasis on dynamic response
- 2007
-
Ingår i: International Journal for Numerical and Analytical Methods in Geomechanics. - : Wiley. - 0363-9061 .- 1096-9853. ; 31:2, s. 261-283
-
Tidskriftsartikel (refereegranskat)abstract
- The displacement field in quasi-brittle material is localized into narrow fracture zones during the process of decohesion. The numerical modelling of the physically propagating displacement discontinuities is considered to be inherently difficult. In this paper, the introduction of continuous discontinuities into the finite element formulation is based on the extended finite element method (X-FEM). This paper extends the theory by further incorporating arbitrary discontinuities in the approximation and presenting numerical procedures to handle several fields of discontinuities. The discontinuous approximation is accomplished by usage of basis functions of very limited support; only non-zero in the elements containing the crack. Moreover, the introduction of discontinuities in a continuum is discussed and a robust numerical procedure is proposed. Further, the mechanical behaviour of cracks in a quasi-brittle material largely governs the overall mechanical response of the material, and the implementation of a cohesive crack model based on anisotropic damage coupled to plasticity is emphasized. Numerical examples for both static and dynamic, transient, loading show that the proposed X-FEM format in combination with the cohesive crack model has a good performance and leads to an efficient implementation. Finally, the proposed forward method for propagation of cracks and introduction of new ones is robust and stable. Copyright (c) 2006 John Wiley & Sons, Ltd.
|
|
| 4. |
- Carlstedt, David, 1984, et al.
(författare)
-
Experimental and computational characterization of carbon fibre based structural battery electrode laminae
- 2022
-
Ingår i: Composites Science and Technology. - : Elsevier BV. - 0266-3538. ; 220
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, electrode laminae consisting of carbon fibres embedded in structural battery electrolyte (CF-SBE electrodes) are characterized with respect to their multifunctional (i.e. combined electrochemical and mechanical) performance utilizing experimental and numerical techniques. The studied material is made from commercially available polyacrylonitrile (PAN)-based carbon fibres and a porous SBE matrix/electrolyte, which is composed of two continuous phases: a solid polymer skeleton (vinyl ester-based) and a Li-salt containing liquid electrolyte. Experimental and numerical studies are performed on CF-SBE electrode half-cells, whereby a coupled electro-chemo-mechanical finite element model is exploited. Results show that, similar to traditional batteries, electrode thickness, transport properties of the electrolyte and applied current significantly affect electrochemical performance. For example, increasing the electrode thickness of the studied CF-SBE electrode from 50 μm to 200 μm results in a reduction in specific capacity of approximately 70/95% for an applied current of 30/120 mA g? 1 of fibres, respectively. Further, Li-insertion induced longitudinal expansion of carbon fibre electrodesare video microscopically recorded during charge/discharge conditions. In liquid electrolyte the total/reversible longitudinal expansion are found to be 0.85/0.8% while for the CF-SBE electrode the reversible expansion is found to be 0.6%. The fibre expansion in the CF-SBE electrode gives rise to residual strains which is demonstrated numerically. We expect that the utilized computational framework and experimental data open a route to develop high-performing, both mechanically and electrochemically, carbon fibre based battery electrode laminae for future lightweight structural components with energy storage ability.
|
|
| 5. |
- Öhman, Mikael, 1983, et al.
(författare)
-
Multiscale Modeling of Sintering of Hard Metal
- 2010
-
Ingår i: 23rd Nordic Seminar on Computational Mechanics. A. Eriksson, G. Tibert. KTH, Stockholm 2010. - 0348-467X. ; , s. 334-336
-
Konferensbidrag (refereegranskat)abstract
- In this contribution, we discuss the multiscale modeling of sintering of hard metal, which is composed of hard particles (WC) with a melted binder (Co). Numerical results areshown for a coupled FE2 analysis involving homogenization of the consolidating compact.
|
|
| 6. |
|
|
| 7. |
- Jänicke, Ralf, 1980, et al.
(författare)
-
Identification of viscoelastic properties from numerical model reduction of pressure diffusion in fluid-saturated porous rock with fractures
- 2019
-
Ingår i: Computational Mechanics. - : Springer Science and Business Media LLC. - 1432-0924 .- 0178-7675. ; 63:1, s. 49-67
-
Tidskriftsartikel (refereegranskat)abstract
- This paper deals with the computational homogenization and numerical model reduction of deformation driven pressure diffusion in fractured porous rock. Exposed to seismic waves, the heterogeneity of the material leads to local fluid pressure gradients which are equilibrated via pressure diffusion. However, a macroscopic observer is not able to measure the diffusion process directly but senses the intrinsic attenuation of an apparently monophasic viscoelastic solid. The aim of this paper is to establish a reliable, yet numerically efficient, computational homogenization method to identify the viscoelastic properties of the macroscopic substitute model. Inspired by the Nonuniform Transformation Field Analysis, we incorporate a Numerical Model Reduction procedure. The proposed method is validated for several scenarios ranging from pressure diffusion in an unfractured poroelastic matrix, via localized pressure diffusion in interconnected fractures embedded in an impermeable matrix, to the fully coupled pressure diffusion both in fractures and the embedding poroelastic matrix.
|
|
| 8. |
|
|
| 9. |
|
|
| 10. |
- Carlstedt, David, 1984, et al.
(författare)
-
Computational modelling of structural batteries accounting for stress-assisted convection in the electrolyte
- 2022
-
Ingår i: International Journal of Solids and Structures. - : Elsevier BV. - 0020-7683. ; 238
-
Tidskriftsartikel (refereegranskat)abstract
- Structural batteries consist of carbon fibres embedded in a porous structural battery electrolyte (SBE), which is composed of two continuous phases: a solid polymer skeleton and a liquid electrolyte containing Li-salt. In this paper we elaborate on a computational modelling framework to study the electro-chemo-mechanical properties of such structural batteries while accounting for the combined action from migration as well as stress-assisted diffusion and convection in the electrolyte. Further, we consider effects of lithium insertion in the carbon fibres, leading to insertion strains. The focus is placed on how the convective contribution to the mass transport within the SBE affects the general electro-chemo-mechanical properties. The numerical results indicate that the convective contribution has only minor influence on the multifunctional performance when the mechanical loading is caused by constrained deformation of constituents during electro-chemical cycling. However, in the case of externally applied mechanical loading that causes severe deformation of the SBE, or when large current pulses are applied, the convective contribution has noticeable influence on the electro-chemical performance. In addition, it is shown that the porosity of the SBE, which affects the effective stiffness as well as the mobility and permeability, has significant influence on the combined mechanical and electro-chemical performance.
|
|
