Ralf Jänicke
Technische Universität Braunschweig
H-index: 15
Europe-Germany
Professor Information
University | Technische Universität Braunschweig |
---|---|
Position | ___ |
Citations(all) | 826 |
Citations(since 2020) | 475 |
Cited By | 526 |
hIndex(all) | 15 |
hIndex(since 2020) | 13 |
i10Index(all) | 24 |
i10Index(since 2020) | 17 |
University Profile Page | Technische Universität Braunschweig |
Research & Interests List
Mechanics
Top articles of Ralf Jänicke
A micromorphic phase-field model for brittle and quasi-brittle fracture
In this manuscript, a robust and variationally consistent technique is proposed for local treatment of the phase-field fracture irreversibility. This technique involves an extension of the phase-field fracture energy functional through a micromorphic approach. Consequently, the phase-field is transformed into a local variable, while a micromorphic variable regularizes the problem. The local nature of the phase-field variable enables an easier implementation of its irreversibility using a pointwise ‘max’ with system level precision. Unlike the popular history variable approach, which also enforces local fracture irreversibility, the micromorphic approach yields a variationally consistent framework. The efficacy of the micromorphic approach in phase-field fracture modelling is demonstrated in this work with numerical experiments on benchmark brittle and quasi-brittle fracture problems in linear elastic media. Furthermore, the …
Authors
Ritukesh Bharali,Fredrik Larsson,Ralf Jänicke
Journal
Computational Mechanics
Published Date
2024/3
Variationally consistent modeling of a sensor-actuator based on shape-morphing from electro-chemical–mechanical interactions
This paper concerns the computational modeling of a class of carbon fiber composites, known as shape-morphing and strain-sensing composites. The actuating and sensing performance of such (smart) materials is achieved by the interplay between electrochemistry and mechanics, in particular the ability of carbon fibers to (de)intercalate Li-ions repeatedly. We focus on the actuation and sensing properties of a beam in conjunction with the appropriate “through-the-thickness” properties. Thus, the electro-chemo-mechanical analysis is essentially two-dimensional, and it is possible to rely heavily on the results in Carlstedt et al. (2020). More specifically, the cross-sectional design is composed of two electrodes, consisting of (partly) lithiated carbon fibers embedded in structural battery electrolyte (SBE), on either side of a separator. As a result, the modeling is hierarchical in the sense that (macroscale) beam action is …
Authors
David Carlstedt,Kenneth Runesson,Fredrik Larsson,Ralf Jänicke,Leif E Asp
Journal
Journal of the Mechanics and Physics of Solids
Published Date
2023/10/1
Three-dimensional reconstruction and computational analysis of a structural battery composite electrolyte
Structural batteries are multifunctional composite materials that can carry mechanical load and store electrical energy. Their multifunctionality requires an ionically conductive and stiff electrolyte matrix material. For this purpose, a bi-continuous polymer electrolyte is used where a porous solid phase holds the structural integrity of the system, and a liquid phase, which occupies the pores, conducts lithium ions. To assess the porous structure, three-dimensional topology information is needed. Here we study the three-dimensional structure of the porous battery electrolyte material using combined focused ion beam and scanning electron microscopy and transfer into finite element models. Numerical analyses provide predictions of elastic modulus and ionic conductivity of the bi-continuous electrolyte material. Characterization of the three-dimensional structure also provides information on the diameter and volume …
Authors
Shanghong Duan,Martina Cattaruzza,Vinh Tu,Robert M Auenhammer,Ralf Jänicke,Mats KG Johansson,Fang Liu,Leif E Asp
Journal
Communications Materials
Published Date
2023/6/29
Variationally consistent homogenization of electrochemical ion transport in a porous structural battery electrolyte
In this paper, we develop a multi-scale modeling framework for a multiphysics problem characterized by electro-chemically coupled ion transport in a Structural Battery Electrolyte (SBE). The governing equations of the problem are established by coupling Gauss law with mass conservation for each mobile species. By utilizing variationally consistent homogenization, we are able to establish a two-scale model where both the macro-scale and sub-scale equations are deduced from a single-scale problem. Investigations of the sub-scale RVE problem show that the transient effects are negligible for the length scales relevant to the studied application, which motivates the assumption of micro-stationarity. In the special case of linear constitutive response, we get a numerically efficient solution scheme for the macro-scale problem that is based on a priori upscaling. As a final step, we demonstrate the numerically efficient …
Authors
Vinh Tu,Fredrik Larsson,Kenneth Runesson,Ralf Jänicke
Journal
European Journal of Mechanics-A/Solids
Published Date
2023/3/1
Electro‐chemo‐mechanical modeling of structural battery electrode materials
In this paper, a linear electro‐chemo‐mechanical model for a structural Lithium ion battery electrode material is presented. The considered material is composed of particles (storing Lithium) embedded in a porous polymer matrix. The pores are filled with a liquid electrolyte. In this three phase material different processes are taken into account: ion diffusion and migration inside the electrolyte, Lithium diffusion inside the particles, electric current inside the binder matrix and particles as well as deformation in these two phases. After presenting the mathematical model, we perform a numerical study of a simple system to investigate the model behavior.
Authors
David Rollin,Fredrik Larsson,Kenneth Runesson,Ralf Jänicke
Journal
PAMM
Published Date
2023/12
Upscaling of chemo-mechanical properties of battery electrode material
A variationally consistent model-based computational homogenization approach for transient chemo- mechanically coupled problems is developed based on the classical assumption of first order prolongation of the displacement and chemical potential fields within a Representative Volume Element (RVE). An upscaling procedure is introduced that is based on the assumption of micro-stationarity for the RVE problem. This is motivated by sufficient separation of time-scales. Periodic boundary conditions on the pertinent fields provide the general variational setting for the uniquely solvable RVE-problems. Due to the assumed linearity and micro-stationary, it is possible to use the pertinent sensitivity analysis for the RVE in order to derive effective macro-scale properties in closed form: the elastic stiffness, the insertion strain tensor and the mobility tensor. Statistically representative results are obtained by considering a …
Authors
David R Rollin,Fredrik Larsson,Kenneth Runesson,Ralf Jänicke
Journal
International Journal of Solids and Structures
Published Date
2023/10/1
Combining spectral and POD modes to improve error estimation of numerical model reduction for porous media
Numerical model reduction (NMR) is used to solve the microscale problem that arises from computational homogenization of a model problem of porous media with displacement and pressure as unknown fields. The reduction technique and an associated error estimator for the NMR error have been presented in prior work, where both spectral decomposition (SD) and proper orthogonal decomposition (POD) were used to construct the reduced basis. It was shown that the POD basis performs better w.r.t. minimizing the residual, but the SD basis has some advantageous properties for the estimator. Since it is the estimated error that will govern the error control, the most efficient procedure is the one that results in the lowest error bound. The main contribution of this paper is further development of the previous work with a proposed combined basis constructed using both SD and POD modes together with an …
Authors
Fredrik Ekre,Fredrik Larsson,Kenneth Runesson,Ralf Jänicke
Journal
Computational Mechanics
Published Date
2022/3
Phase-field fracture irreversibility using the slack variable approach
In this manuscript, the phase-field fracture irreversibility constraint is transformed into an equality-based constraint using the slack variable approach. The equality-based fracture irreversibility constraint is then introduced in the phase-field fracture energy functional using the Lagrange Multiplier Method and the Penalty method. Both methods are variationally consistent with the conventional variational inequality phase-field fracture problem, unlike the history-variable approach. Thereafter, numerical experiments are carried out on benchmark problems in brittle and quasi-brittle fracture to demonstrate the efficacy of the proposed method.
Authors
Ritukesh Bharali,Fredrik Larsson,Ralf Jänicke
Journal
arXiv preprint arXiv:2202.10040
Published Date
2022/2/21
Professor FAQs
What is Ralf Jänicke's h-index at Technische Universität Braunschweig?
The h-index of Ralf Jänicke has been 13 since 2020 and 15 in total.
What are Ralf Jänicke's top articles?
The articles with the titles of
A micromorphic phase-field model for brittle and quasi-brittle fracture
Variationally consistent modeling of a sensor-actuator based on shape-morphing from electro-chemical–mechanical interactions
Three-dimensional reconstruction and computational analysis of a structural battery composite electrolyte
Variationally consistent homogenization of electrochemical ion transport in a porous structural battery electrolyte
Electro‐chemo‐mechanical modeling of structural battery electrode materials
Upscaling of chemo-mechanical properties of battery electrode material
Combining spectral and POD modes to improve error estimation of numerical model reduction for porous media
Phase-field fracture irreversibility using the slack variable approach
...
are the top articles of Ralf Jänicke at Technische Universität Braunschweig.
What are Ralf Jänicke's research interests?
The research interests of Ralf Jänicke are: Mechanics
What is Ralf Jänicke's total number of citations?
Ralf Jänicke has 826 citations in total.
What are the co-authors of Ralf Jänicke?
The co-authors of Ralf Jänicke are Forest Samuel, Ernst Rank, Klaus Holliger, Karin Lundgren, Erik H. Saenger, Leif E Asp.