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Laser beam welding is a metal fusion technique that, with its high advance speed and low thermal distortion, is used more frequently nowadays in industry. During welding, the solidification front is located in the so‐called mushy zone, which forms the transition region between the completely solidified and mixture zone of solid and fluid material behind the laser beam. In this zone, various process...
In the present work, a mixed least‐squares finite element method (LSFEM) is used, which is applied on the partial differential equations arising from the Theory of Porous Media (TPM), see for example [1, 2, 3]. Since the LSFEM is not limited to the LBB condition, the method has some theoretical advantages over the well‐known (mixed) Galerkin method, see [4]. In particular, the LSFEM leads to positive...
For modeling materials with size‐effects, the classical Cauchy linear elasticity theory and first‐order homogenization procedures are insufficient. Enriched continua are able to capture such phenomena in principle. In this work, we model the size‐effects of metamaterial beams via the relaxed micromorphic continuum. The material parameters of the relaxed micromorphic model are evaluated. We present...
This work presents a multi‐phase approach to model freezing processes within a coupled finite element formulation using the Theory of Porous Media (TPM), see also [1]. The focus of the study is to enhance the numerical stability for the volume fraction ice as is it highly sensitive to phase discontinuities. To address this issue, a discontinuous approximation is employed for the volume fraction ice...
Current research focuses on the induction of residual stresses in a component during its manufacturing process, which shows a significant impact on the final component's properties. During the manufacturing of a hot bulk forming component, the temperature evolution allows to influence the resulting residual stress state efficiently and purposefully. Following the characterization of residual stresses...
In this paper, we propose an efficient numerical scheme for the prediction of the magnetic stray fields in two‐dimensional random microheterogeneous materials. Since data‐driven models require thousands of training datasets, Finite Element Method simulations appear to be too time consuming. Therefore, a stochastic model based on Brownian motion, which uses an efficient evaluation of stochastic transition...
The influence of different fiber contents and orientations on the overall material behavior of steel microfiber reinforced UHPC is studied. To analyze the failure behavior of UHPC, the three‐point bending beam tests at low cycle is investigated experimentally and simulated numerically. For that purpose, recently developed phenomenological material model, see our recent works [1] and [2], based on...
This work shows an adaptive Model Order Reduction (MOR) scheme for the computation of unit cells with non‐linear material behavior. A reduction of dimensionality and computational cost is achieved by projecting the high‐fidelity system of equations (SOE) from the full vector space to a lower dimensional subspace. An adaptive algorithm updates the projection operator, which is initially gained from...
The striving for the independence of fossil energy sources by further development of renewable energies as well as the change in mobility act as a driving force on technological innovations. Magnetic materials with improved magnetic efficiency help to push the limits for optimized, low‐loss power conversion applications and electrification. Besides improving the chemical composition, that is, gaining...
This paper tries to simulate a hydraulic failure by using a ternary, saturated, quasi‐static Theory of Porous Media (TPM) model. The concept of a hydraulic failure is shortly explained and the derivation of the TPM setup including the limitation of the volume fractions is depicted. A schematic excavation with a sheet piling is used to test the created model and prove the general feasibility of the idea.
Laser beam welding is a contact free fusion technique which has gained importance during the last years due to rising need for automatization in industrial processes. However, a well‐known problem is the formation of solidification cracks in the rear region of the melting pool. In order to investigate the formation of solidification cracks which is highly dependent on the chemical composition, the...
In this contribution we present an approach to generate a data driven surrogate model for the prediction of permeabilities and flow through two dimensional random micro‐heterogeneous materials. The laminar flow is well described by Darcy's law. In order to achieve an efficient computational tool for the generation of the database (up to 103 realizations), needed for the training of the neural networks,...
The cost‐ and time‐efficient design of today's manufacturing processes is closely linked to numerical simulations. By developing and applying suitable simulation models, component properties can be specifically predicted and, if necessary, modified according to the customer's specifications. One important aspect of this is the adjustment towards advantageous residual stress profiles, for example to...
In this contribution, an adaptive method for Model Order Reduction (MOR) is presented for simulating physically non‐linear material behavior of micro‐heterogeneous structures. The method is purely online and includes a Galerkin projection, which is performed using a projection operator initially gained by a Proper Orthogonal Decomposition (POD). By this projection, the number of degrees of freedom...
A phenomenological material model is developed to understand the pseudo‐ductile material behavior of steel fiber reinforced high performance concrete (HPC) during failure. In that respect, an energy function is formulated using an additive composition of a transversal isotropic elasto‐plastic model and an elasto‐plastic phase‐field model representing the individual behavior of the steel fibers and...
High performance magnets play an important role in critical issues of modern life such as renewable energy supply, independence of fossile resource and electro mobility. The performance optimization of the established magnetic material system relies mostly on the microstructure control and modification. Here, finite element based in‐silico characterizations, as micromagnetic simulations can be used...
The FE2 method, cf. [1], a direct micro‐macro homogenization approach, has become a standard procedure for scale‐transition applications. Therein, the modeling of a micro‐heterogeneous material described by a representative volume element (RVE) based on realistic microstructures can give rise to a barely unmanageable computational effort. Alternatively, statistically similar RVEs (SSRVEs) can be used,...
Mechanical metamaterials are media with periodic unit cells comprised of tailored geometry in order to accomplish extraordinary bulk mechanical properties which can not be found in conventional materials. However, metamaterials exhibit size‐effect phenomena which can be captured by enriched continua. In this work, the relaxed micromorphic model will be used to reproduce the mechanical response of...
The direct current (DC) and alternative current (AC) electromechanically coupled phenomena have been reported in carbon nanotube (CNT)‐based nanocomposite sensors. In this contribution, a unified micromechanics‐based model is established for the DC and AC strain sensors. The electric damage and volume change of nanocomposite are considered to be responsible for the electromechanically coupled effects...
Earth System Models (ESM), simulating sea ice and its interaction with the atmosphere and open ocean, require reliable physical, chemical, and biological input from measurements. There is limited data available from the Marginal Ice Zone of the Antarctic, where sea ice growth mechanisms differ from the Arctic. The main objective of this study is to review existing work related to Antarctic sea ice...
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