arXiv subjects

Carolin Körner

Publications and source records attributed to Carolin Körner.

3 recordsLinked to original sources

arXiv2017

Evolution of full phononic band gaps in periodic cellular structures

Cellular materials not only show interesting static properties but can also be used to manipulate dynamic mechanical waves. In this contribution, the existence of phononic band gaps in periodic cellular structures is experimentally shown via sonic transmission experiment. Cellular structures with varying numbers of cells are excited by piezoceramic actuators and the transmitted waves are measured by piezoceramic sensors. The minimum number of cells necessary to form a clear band gap is determined. A rotation of the cells does not have an influence on the formation of the gap, indicating a complete phononic band gap. The experimental results are in good agreement with the numerically obtained dispersion relation.

cond-mat.mtrl-sci↗

arXiv2015

Numerical Investigations on Hatching Process Strategies for Powder Bed Based Additive Manufacturing using an Electron Beam

This paper investigates in hatching process strategies for additive manufacturing using an electron beam by numerical simulations. The underlying physical model and the corresponding three dimensional thermal free surface lattice Boltzmann method of the simulation software are briefly presented. The simulation software has already been validated on the basis of experiments up to 1.2 kW beam power by hatching a cuboid with a basic process strategy, whereby the results are classified into `porous', `good' and `uneven', depending on their relative density and top surface smoothness. In this paper we study the limitations of this basic process strategy in terms of higher beam powers and scan velocities to exploit the future potential of high power electron beam guns up to 10 kW. Subsequently, we introduce modified process strategies, which circumvent these restrictions, to build the part as fast as possible under the restriction of a fully dense part with a smooth top surface. These process strategies are suitable to reduce the build time and costs, maximize the beam power usage and therefore use the potential of high power electron beam guns.

cs.CE↗

arXiv2014

Validation Experiments for LBM Simulations of Electron Beam Melting

This paper validates 3D simulation results of electron beam melting (EBM) processes comparing experimental and numerical data. The physical setup is presented which is discretized by a three dimensional (3D) thermal lattice Boltzmann method (LBM). An experimental process window is used for the validation depending on the line energy injected into the metal powder bed and the scan velocity of the electron beam. In the process window the EBM products are classified into the categories, porous, good and swelling, depending on the quality of the surface. The same parameter sets are used to generate a numerical process window. A comparison of numerical and experimental process windows shows a good agreement. This validates the EBM model and justifies simulations for future improvements of EBM processes. In particular numerical simulations can be used to explain future process window scenarios and find the best parameter set for a good surface quality and dense products.

cs.CE↗