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arXiv 2024年

作者： Weichert, Dorina Kister, Alexander Houben, Sebastian Link, Patrick Ernis, Gunar Fraunhofer Institute for Intelligent Analysis and Information Systems IAIS Sankt Augustin Germany VP.1 eScience Federal Institute for Materials Research and Testing BAM Berlin Germany University of Applied Sciences Bonn-Rhein-Sieg Sankt Augustin Germany Fraunhofer Institute for Machine Tools and Forming Technology IWU Chemnitz Germany Institute of Mechatronic Engineering TUD Dresden University of Technology Dresden Germany

The practical use of Bayesian Optimization (BO) in engineering applications imposes special requirements: high sampling efficiency on the one hand and finding a robust solution on the other hand. We address the case of adversarial robustness, where all parameters are controllable during the optimization process, but a subset of them is uncontrollable or even adversely perturbed at the time of application. To this end, we develop an efficient information-based acquisition function that we call Robust Entropy Search (RES). We empirically demonstrate its benefits in experiments on synthetic and real-life data. The results show that RES reliably finds robust optima, outperforming state-of-the-art algorithms. © 2024, CC BY-SA.

关键词： Entropy

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Robust entropy search for safe efficient Bayesian optimization 24

Robust entropy search for safe efficient Bayesian optimizati...

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Proceedings of the Fortieth Conference on Uncertainty in Artificial Intelligence

作者： Dorina Weichert Alexander Kister Sebastian Houben Patrick Link Gunar Ernis Fraunhofer Institute for Intelligent Analysis and Information Systems IAIS Sankt Augustin Germany VP.1 eScience Federal Institute for Materials Research and Testing BAM Berlin Germany University of Applied Sciences Bonn-Rhein-Sieg Sankt Augustin Germany Fraunhofer Institute for Machine Tools and Forming Technology IWU Chemnitz Germany and Institute of Mechatronic Engineering TUD Dresden University of Technology Dresden Germany

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Automated porosity assessment of parts produced by Laser Powder Bed Fusion using Convolutional Neural Networks

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Procedia CIRP 2021年 104卷 1434-1439页

作者： Jan Klein Martin Jaretzki Michael Schwarzenberger Steffen Ihlenfeldt Welf-Guntram Drossel Technische Universität Dresden Chair of Machine Tools Development and Adaptive Controls 01069 Dresden Fraunhofer Institute for Machine Tools and Forming Technology (IWU) Nöthnitzer Str. 44 01187 Dresden Germany

Laser Powder Bed Fusion (LPBF) is especially interesting for applications in industries with high quality requirements. There are different expensive and time-consuming strategies for quality assurance. A cheaper and faster approach is to analyze the data acquired during fabrication. In this work Convolutional Neural Networks (CNN) are investigated as a tool for data analysis of meltpool monitoring data. The goal is to automatically distinguish between porous and non-porous part regions. Therefore, the training data is categorized based on CT-scans of the test specimens. For increased interpretability of the results, Gradient-Weighted Class Activation Maps (Grad-CAM) are used.

关键词： Additive Manufacturing Laser Beam Melting LPBF Process Monitoring Quality Assessment Porosity In-process sensing Melt pool monitoring CNN Neural Networks

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Characterization of vibration in continuous generating grinding and resulting influence on tooth flank topography and gear excitation

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Procedia CIRP 2021年 99卷 208-213页

作者： Jonas Böttger Simon Kimme Welf-Guntram Drossel Institute for Machine Tools and Production Processes IWP Chemnitz University of Technology Reichenhainer Str. 70 09126 Chemnitz Germany Fraunhofer Institute for Machine Tools and Forming Technology IWU Reichenhainer Str. 88 09126 Chemnitz Germany

Besides harmonic meshing frequencies, excitation behavior of gears is highly affected by micro geometry of tooth surface caused by waviness on gear flank topography. Errors in finishing processes like continuous generating gear grinding are examined to demonstrate their impact on gear flank topography under consideration of characteristic waviness with a simulation model. Results of an experimental investigation on manufactured topography and measured transmission error show well correlation with the model. The pursued analysis of characteristic cutting volume in frequency domain of systematically considered process errors is a reasonable step towards the prediction of process conditions in the manufacturing process.

关键词： Grinding Gear Vibration Simulation

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Subjective validation for short-term material flow simulation

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Procedia CIRP 2025年 134卷 562-566页

作者： Heiner Reinhardt Boran Bogdanow Roman Arnold Bastian Prell Philipp Klimant Frank Seifert Mahtab Mahdaviasl Steffen Ihlenfeldt Fraunhofer Institute for Machine Tools and Forming Technology IWU Reichenhainer Straße 88 09126 Chemnitz Germany Volkswagen Sachsen GmbH Kauffahrtei 47 09120 Chemnitz Germany Technical University of Applied Sciences Wildau Hochschulring 1 15745 Wildau Germany Professorship Virtual Technologies Hochschule Mittweida - University of Applied Sciences Technikumplatz 17 09648 Mittweida Germany Chemnitz University of Technology Straße der Nationen 62 09111 Chemnitz Germany Institute of Machine Tools and Control Engineering Technische Universität Dresden Helmholtzstraße 7a 01062 Dresden Germany

Material flow simulation, by means of discrete event simulation (DES), is frequently applied to support decision-making in production planning and control. However, manual modeling can be time-consuming and error-prone. Hence, numerous studies propose the automation of model generation and synchronization to overcome these challenges. However, in this context, validation techniques are rarely addressed. Therefore, we introduce a subjective validation technique for short-term material flow simulation based on a coherent methodology for data acquisition and visualization. The methodology is utilized to evaluate the outcome of an approach for computerized model generation and simulation. By means of an industrial use case, we hypothesize the causes for the deviation between the operation of a manufacturing system and the simulation of its generated virtual companion.

关键词： Digital Twin Simulation Quality Optimization Manufacturing system Control Analysis

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Evolutionary optimization of deep-drawing processes on servo screw presses with freely programmable force and motion functions 54

Evolutionary optimization of deep-drawing processes on servo...

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54th CIRP Conference on Manufacturing Ssystems, CMS 2021

作者： Kriechenbauer, Sebastian Müller, Peter Mauermann, Reinhard Drossel, Welf-Guntram Fraunhofer Institute for Machine Tools and Forming Technology IWU NOthnitzer Straße 44 Dresden01187 Germany Technische Universität Chemnitz Institut für Werkzeugmaschinen und Produktionsprozesse Professur Adaptronik und Funktionsleichtbau Chemnitz09107 Germany

Servo screw presses with freely programmable force and motion functions lead to innovative forming technologies for deep drawing of sheet metals. The advanced application potential of the machine type is mainly based on the accuracy and flexibility. Due to the increase of process parameters in deep-drawing processes with variable force and motion functions, the standards for method planning (consideration of machine properties, parameterization of the movement functions) in comparison to conventional deep-drawing processes increase. The high number of parameters motivates the aim: A systematic design of deep-drawing processes with free force and motion functions on servo presses based on computational science methods. In the context of this publication, the determination of optimal parameters (force and motion functions) for a deep-drawing process with superimposed vibrations on servo screw presses will be investigated. With the help of evolutionary optimization approaches a process-design for a deep-drawing process with superposition of low-frequency oscillations will be carry out. The results of the evolutionary optimization approaches are validated by experiments with cross die part. © 2021 The Author(s).

关键词： Optimization

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Combined laser hardening and laser surface texturing forming tool 1.2379 11

Combined laser hardening and laser surface texturing forming...

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11th CIRP Conference on Photonic Technologies, LANE 2020

作者： Aragaw, Endalkachew Mekonnen Gärtner, Eric Schubert, Andreas Institute for Machine Tools and Production Processes Chemnitz University of Technology Reichenhainer Str. 70 09107 Germany Fraunhofer Inistitute for Machine tools and Forming Technology IWU Reichenhainer Str. 88 09126 Germany

This paper deals with the tribological performance of forming tool steel 1.2379. Laser hardening and Laser surface texturing are proposed as processes to improve this tribological performance. Hardening influences the surface hardness and wear resistance. While considering the parameter and the specific material, the correlation between heating power and material property is first modelled using FEM of the heat transfer. Based on the modelling result, the realization is performed by nanosecond laser and analyzed by SEM and by comparing the micro - hardness comparison with a reference value. Then textures are integrated into the hardened surface by picosecond laser ablation while focusing on its suitability for smooth dimples and on the examination by pin-on-disk tests for the effect of incorporating textures on the friction performance. Lower friction coefficients between tool and workpiece improve tool durability and product quality as well. © 2020 The Authors. Published by Elsevier B.V.

关键词： Microhardness

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Enhancing End-of-Line Defect Classifications and Evaluating Early Testability for Inline Test Stands Using NVH Measurements

Enhancing End-of-Line Defect Classifications and Evaluating ...

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International Electric Drives Production Conference (EDPC)

作者： Jakob Bonart Philipp Hümmer Welf-Guntram Drossel Technology development E-Drive BMW AG MunichGermany Fraunhofer Institute for Machine Tools and Forming Technology Chemnitz Germany

ISBN: (纸本)9781665418102

Production lines for electric drives consist of successive assembly steps. The highly integrated topology of the unit can lead to complex faults caused by poor components or incorrect assembly. To minimize the added value of a bad motor, a noise-vibration-harshness (NVH) measurement is performed on an in-line test bench (IL). Following the IL, other components (gearbox, inverter, …) are assembled, resulting in a finished electric drive unit. The final state is again tested by a NVH measurement on an end-of-line (EOL) test bench. A novel approach is presented that combines the results of both test benches into an overall picture, thus creating a contextual environment for the EOL. Depending on the interaction of the two test benches, different implications are derived. An identified defect on the EOL can be further classified by deviations already present in the IL test. Deviations that are not present on the IL also indicate processes between the two test stands and thus increase the ability to correctly classify defects on the EOL. If deviations are present on the IL, an indicator of significant testability is derived. This can be further used to accurately detect defects that were previously only detected on the EOL.

关键词： Vibrations Location awareness Electric variables measurement Production Manuals Vibration measurement Topology

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Everting of tubular net structures based on Shape Memory Alloys

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Engineering Research Express 2021年第2期3卷

作者： Hensel, Sebastian Boxberger, Lukas Weisheit, Linda Schellnock, Julia Thielsch, Juliane Riedel, Frank Drossel, Welf-Guntram Fraunhofer Institute for Machine Tools and Forming Technology IWU Dresden01187 Germany Professorship for Adaptronics and Lightweight Design Chemnitz University of Technology Chemnitz09126 Germany

Foldable technical structures can be used to provide a temporary additional volume. In nature, a tubular folding application is the extension of the snail eye. The present study uses this approach. A transformation into a technical application is only successful if the high eversion loads are considered. The study aims to develop a method to realize such structures based on a metallic wire net structure. The tube consists of Shape Memory Alloy (SMA) pieces connected by developed crimp elements produced by additive manufacturing. Additive manufacturing was used to provide a fast and effective way to make several crimp element geometries available to define a preferred variant. In a preliminary building study, the printing parameters for crimp element production were improved. The tubular structure development is assisted by numerical simulation of the eversion process. The SMA material model parameters were identified with experimental tension tests. A feasible way to connect additively manufactured crimp elements with SMA wire was found within a joining method study. Tension tests of the connections protect against pull-out failure. The eversion process was investigated using a high-speed camera system. Multiple eversion of the developed structure is possible without failure. © 2021 The Author(s). Published by IOP Publishing Ltd.

关键词： 3D printers

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Cutting parameter study of CFRP machining by turning and turn-milling 13

Cutting parameter study of CFRP machining by turning and tur...

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13th CIRP Conference on Intelligent Computation in Manufacturing Engineering, CIRP ICME 2019

作者： Sauer, Konstantin Hertel, Matthias Fickert, Sandro Witt, Marco Putz, Matthias Chemnitz University of Technology Institute for Machine Tools and Production Processes Reichenhainer Str. 70 Chemnitz09126 Germany Fraunhofer Institute for Machine Tools and Forming Technology Reichenhainer Str. 88 Chemnitz09126 Germany

The use of carbon fibre reinforced plastic (CFRP) structures in rotationally symmetrical components opens up a new field of lightweight construction with great potential for reducing the mass of moving components. Due to the material anisotropy, the machining of these structures can cause component damages. In this paper, the machining results of CFRP shafts conducted by turning and orthogonal turn-milling are presented. The characteristics of the applied processes are evaluated concerning the achievable shape and surface quality of the workpiece. Furthermore, the possibilities for the machining of fits on CFRP shafts are discussed. © 2020 The Authors.

关键词： Turning

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