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Extension of Flow Behaviour and Damage Models for Cast Iron Alloys with Strain Rate Effect

Chinese Journal of Mechanical Engineering 2024年第3期37卷 297-310页

作者： Chuang Liu Dongzhi Sun Xianfeng Zhang Florence Andrieux Tobias Gersterc School of Mechanical Engineering Nanjing University of Science and TechnologyNanjing 210094China fraunhofer Institute for Mechanics of Materials(IWM) 79108 FreiburgGermany fraunhofer Institute for High Speed Dynamics Ernst-Mach-Institute(EMI)79104 FreiburgGermany

Cast iron alloys with low production cost and quite good mechanical properties are widely used in the automotive *** study the mechanical behavior of a typical ductile cast iron(GJS-450)with nodular graphite,uni-axial quasi-static and dynamic tensile tests at strain rates of 10^(-4),1,10,100,and 250 s^(-1)were carried *** order to investigate the influence of stress state on the deformation and fracture parameters,specimens with various geometries were used in the *** strain curves and fracture strains of the GJS-450 alloy in the strain rate range of 10^(-4)to 250 s^(-1)were obtained.A strain rate-dependent plastic flow model was proposed to describe the mechanical behavior in the corresponding strain-rate *** available damage model was extended to take the strain rate into account and calibrated based on the analysis of local fracture *** with the proposed plastic flow model and the damage model were conducted to observe the deformation and fracture *** results show that the strain rate has obviously nonlinear effects on the yield stress and fracture strain of GJS-450 *** predictions with the proposed plastic flow and damage models at various strain rates agree well with the experimental results,which illustrates that the rate-dependent plastic flow and damage models can be used to describe the mechanical behavior of cast iron alloys at elevated strain *** proposed plastic flow and damage models can be used to describe the deformation and fracture analysis of materials with similar properties.

关键词： Dynamic behavior of materials Strain rate dependency Damage model Voce model Cast iron

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Note on:“Ballistic model for the prediction of penetration depth and residual velocity in adobe:A new interpretation of the ballistic resistance of earthen masonry”

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Defence Technology（防务技术） 2024年第1期31卷 607-609页

作者： Andreas Heine Matthias Wickert fraunhofer EMI Ernst-Zermelo-Str.479104FreiburgGermany

A recently published modeling approach for the penetration into adobe and previous approaches implicitly criticized are reviewed and *** article contains a note on the paper titled“Ballistic model for the prediction of penetration depth and residual velocity in adobe:A new interpretation of the ballistic resistance of earthen masonry”(DOI:https://***/10.1016/***.2018.07.017).Reply to the Note from Li Piani et al is linked to this article.

关键词： adobe prediction earth

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Experimental and numerical investigation on alternatives to sandy gravel

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Defence Technology（防务技术） 2024年第1期31卷 130-141页

作者： V.Denefeld H.Aurich fraunhofer Institute for High-Speed Dynamics Ernst-Mach-Institut(EMI)Ernst-Zermelo-Str.479104FreiburgGermany fraunhofer Institute for High-Speed Dynamics Ernst-Mach-Institut(EMI)Am Christianswuhr 279400KandernGermany

The NATO agreement STANAG 4569 defines the protection levels for the occupants of logistic and light armored *** Allied Engineering Publication,AEP-55,Volume 2 document outlines the test conditions for underbelly improvised explosive device(IEDs),which must be buried in water-saturated sandy *** use of sandy gravel has some drawbacks,for instance reproducibility,time consumption,and *** paper focuses on the investigation of four alternatives to sandy gravel,which could produce similar specific and cumulative impulses:a concrete pot filled with water,a concrete pot filled with quartz sand,a steel pot without filling and a concrete pot filled with glass spheres(diameter 200μm—300μm)and different water *** impulses are measured with a ring technology developed at the fraunhofer EMI.A numerical soil model based on the work of Marrs,2014 and Fi serov a,2006 and considering the soil moisture was used to simulate the experiments with glass spheres at different water contents,showing much better agreement with the experiments than the classical Laine&Sandvik model,even for high saturation *** results can be used to create new test conditions at original scale that are more cost-effective,more reproducible and simpler to manage in comparison to the current tests carried out with STANAG sandy gravel.

关键词： Improvised explosive device(IED) Specific impulse Momentum transfer Sandy gravel Glass spheres Numerical model Soil moisture

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Transfer learning applications for autoencoder-based anomaly detection in wind turbines

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Energy and AI 2024年第3期17卷 1-10页

作者： Cyriana M.A.Roelofs Christian Gück Stefan Faulstich fraunhofer IEE Joseph-Beuys-Straße 834117 KasselGermany

Anomaly detection in wind turbines typically involves using normal behaviour models to detect faults *** behaviour models are often implemented through the use of neural networks,of which autoencoders are particularly popular in this ***,training autoencoder models for each turbine is time-consuming and resource ***,transfer learning becomes essential for wind turbines with limited data or applications with limited computational *** study examines how cross-turbine transfer learning can be applied to autoencoder-based anomaly ***,autoencoders are combined with constant thresholds for the reconstruction error to determine if input data contains an *** models are initially trained on one year’s worth of data from one or more source wind *** are then fine-tuned using small amounts of data from the target wind *** methods for fine-tuning are investigated:adjusting the entire autoencoder,only the decoder,or only the threshold of the *** performance of the transfer learning models is compared to baseline models that were trained on one year’s worth of data from the target wind *** results of the tests conducted in this study indicate that models trained on data of multiple wind turbines do not improve the anomaly detection capability compared to models trained on data of one source wind *** addition,modifying the model’s threshold can lead to comparable or even superior performance compared to the baseline,whereas fine-tuning the decoder or autoencoder further enhances the models’performance.

关键词： Condition monitoring Transfer learning Autoencoder Anomaly detecti on Wind turbines Fault detection

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Methodology for the assessment of the friction torque of ball slewing bearings considering preload scatter

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Friction 2024年第8期12卷 1838-1857页

作者： Iñigo ESCANCIANO Iker HERAS Florian SCHLEICH Josu AGUIRREBEITIA Department of Mechanical Engineering University of the Basque CountryBilbao 48080Spain fraunhofer-Institute for Wind Energy Systems IWES Hamburg 27572Germany

This manuscript presents an innovative methodology for the assessment of the friction torque of ball slewing *** methodology aims to overcome the limitations of state-of-the-art approaches,especially when the friction torque is conditioned by the preload of the *** this end,the authors propose to simulate the preload scatter when solving the load distribution problem,prior to the friction torque *** preload scatter allows to simulate a progressive transition of the balls from a four-point contact state to a two-point contact *** implementing this capability into an analytical model,the authors achieve a successful correlation with experimental ***,depending on the stiffness of the structures to which the bearing is assembled,it is demonstrated that the rigid ring assumption can lead to inaccurate friction torque results when a tilting moment is *** methodology described in this research work is meant to have a practical ***,the manuscript provides guidelines about how to use and tune the analytical model to get a reliable friction torque prediction tool.

关键词： slewing bearing ball bearing friction torque preload scatter

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Dependence of impact regime boundaries on the initial temperatures of projectiles and targets

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Defence Technology（防务技术） 2024年第1期31卷 49-57页

作者： Stefano Signetti Andreas Heine fraunhofer-Institut für Kurzzeitdynamik Ernst-Mach-InstitutEMIErnst-Zermelo-Str.479104 Freiburg im BreisgauGermany

Towards higher impact velocities,ballistic events are increasingly determined by the material *** effects might range from moderate thermal softening to full phase *** particular,it is of great interest to quantify the conditions for incipient or full melting of metals during impact interactions,which result in a transition from still strength-affected to hydrodynamic material *** this work,we investigate to which extent the respective melting thresholds are also dependent on the initial,and generally elevated,temperatures of projectiles and targets before *** is studied through the application of a model developed recently by the authors to characterize the transition regime between high-velocity and hypervelocity impact,for which the melting thresholds of materials were used as the defining *** obtained results are expected to be of general interest for ballistic application cases where projectiles or targets are *** conditions might result,for example,from aerodynamic forces acting onto a projectile during atmospheric flight,explosive shapedcharge-jet formation or armor exposure to environmental *** performed analyses also broaden the scientific understanding of the relevance of temperature in penetration events,generally known since the 1960s,but often not considered thoroughly in impact studies.

关键词： Ballistic impact Thermal effects Metallic targets Energy partitioning Homologous temperature

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Pressurized environments directly influence friction and wear of dry steel contacts—Investigations in a novel high fluid pressure tribometer

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Friction 2024年第7期12卷 1599-1617页

作者： Paul REICHLE Jakob BARZ Georg UMLAUF Günter E.M.TOVAR Institute of Interfacial Process Engineering and Plasma Technology(IGVP) University of StuttgartStuttgart 70569Germany fraunhofer Institute for Interfacial Engineering and Biotechnology(IGB) Stuttgart 70569Germany

To reduce the usage of classical lubricants in deep drawing,a new tribological system based on volatile lubricants was ***,a volatile medium is injected under high pressure into the interstice between drawing tool and sheet *** on temperature and pressure,the temporary lubricant may exist in its gaseous or liquid *** this study,a novel high fluid pressure tribometer was designed to investigate the friction and wear of dry steel contacts under comparable conditions like in dry deep ***,a new ball-on-disc tribometer was designed and integrated into a high-pressure *** specifically investigate the effects of different environments(technical air,liquid and gaseous carbon dioxide,nitrogen,argon)at atmospheric and high pressure(0.1 MPa,6 MPa)on tribology,the specimens and all components were operating *** the experiments,the friction was measured *** show that the highest friction occurs in air and the lowest in carbon dioxide *** to the experiments,the wear of the specimens was assessed along with changes in surface chemistry related to tribochemical ***,the tribology of the dry sliding contacts is correlated to changes of the surface *** differences as well as similarities regarding the different fluid environments are *** the results show,the differences between the media used are most pronounced at elevated ***,this work gives clear indications on the suitability of volatile lubricants in dry friction or rather gas lubrication,especially for dry deep drawing.

关键词： dry friction and dry wear gas lubrication carbon dioxide tribo-layer dry metal forming

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Fatty acids derived from oviposition systems guide female black soldier flies(Hermetia illucens)toward egg deposition sites

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Insect Science 2024年第4期31卷 1231-1248页

作者： Patrick Klüber Emna Arous Jeanny Jerschow Marco Fraatz Daniel Bakonyi Martin Rühl Holger Zorn Department Bioresources Fraunhofer Institute for Molecular Biology and Applied EcologyGiessenGermany Institute of Food Chemistry and Food Biotechnology Justus Liebig University GiessenGiessenGermany

The black soldier fly,Hermetia illucens,comes with big promises for industrial purposes since its larvae feed polyphagously on a broad spectrum of organic ***,research focusing on adult flies is scarce,which is inconsistent with their reproductive relevance within the rearing *** particular,directed oviposition is a challenge in artificial ***,decomposing organic matter is commonly used as oviposition substrate,which has extensive potential for improvement in view of the lack of standardization and the risk of microbial ***,we identified three fatty acids and one fatty acid methyl ester derived from the surface of old oviposition sites and targeted to elucidate their effect on preference behavior and oviposition site selection using Y-olfactometry and prepared oviposition sites,*** to tetradecanoic acid attracted gravid females and stimulated oviposition most strongly,while decanoic acid demonstrated a repulsive *** kept in mixed-sex populations were attracted by tetradecanoic acid,resulting in a higher egg mass found in the compound box(3.0–11.4 fold),a≥2.3 fold reduction of nonspecifically deposited eggs,and the highest total egg ***,decanoic and dodecanoic acid caused females to lay a greater proportion of eggs nonspecifically outside both *** data suggest that fatty acids,especially tetradecanoic acid,are important cues for oviposition site selection in black soldier *** order to achieve a directed oviposition behavior,the role of further short-and long-chain fatty acids as attractants should be examined.

关键词： black soldier fly Hermetia illucens fatty acids insects as food and feed oviposition oviposition site selection tetradecanoic acid

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Energy Disaggregation of Industrial Machinery Utilizing Artificial Neural Networks for Non-intrusive Load Monitoring

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Energy and AI 2024年第3期17卷 342-356页

作者： Philipp Pelger Johannes Steinleitner Alexander Sauer fraunhofer Institute for Manufacturing Engineering and Automation IPA Stuttgart 70569Germany Institute for Energy Efficiency in Production(EEP) University of StuttgartStuttgart 70569Germany

This paper explores the application of non-intrusive load monitoring techniques in the industrial sector for disaggregating the energy consumption of machinery in manufacturing processes. With an increasing focus on energy efficiency and decarbonization measures, achieving energy transparency in production becomes crucial. Utilizing non-intrusive load monitoring, energy data analysis and processing can provide valuable insights for informed decision-making on energy efficiency improvements and emission reductions. While non-intrusive load monitoring has been extensively researched in the building and residential sectors, the application in the industrial manufacturing domain needs to be further explored. This paper addresses this research gap by adapting established non-intrusive load monitoring techniques to an industrial dataset. By employing artificial neural networks for energy disaggregation, the determination of energy consumption of industrial machinery is made possible. Therefore, a generally applicable cross-energy carrier method to disaggregate the energy consumption of machinery in manufacturing processes is developed using a design science research approach and validated through a practical case study utilizing a compressed air demonstrator. The results show that the utilization of artificial neural networks is well-suited for energy disaggregation of industrial data, effectively identifying on and off states, multi-level states and continuously variable states. Non-intrusive load monitoring should be further considered in the research of emerging artificial intelligence technologies in energy consumption evaluation. It can be a viable alternative for intrusive load monitoring and is a prerequisite to installing energy meters for every machine.

关键词： Non-intrusive load monitoring Energy transparency Energy consumption evaluation Industrial manufacturing Artificial neural networks

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Deep learning-based prediction of 3-dimensional silver contact shapes enabling improved quality control in solar cell metallization

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Energy and AI 2024年第3期17卷 513-524页

作者： Marius Singler Akshay Patil Linda Ney Andreas Lorenz Sebastian Tepner Florian Clement fraunhofer Institute for Solar Energy Systems(ISE) Heidenhofstr.279110 FreiburgGermany EKRA Automatisierungstechnik GmbH Zeppelinstraße 1674357 BonnigheimGermany

The industrial metallization of Si solar cells predominantly relies on screen printing,with silver as the preferred electrode ***,the design of commercial screens often leads to suboptimal silver usage and increased electrical resistance due to print-related inhomogeneities like mesh marks,constrictions and ***-time monitoring of quality parameters during production has thus become increasingly *** inline optical quality control systems usually only include 2D visualizations of the printed layout,which limits their effectiveness in quality *** that allow 3D measurements are usually slow,expensive,and therefore not worth considering in most *** research focuses on the development of a model that can estimate the three-dimensional shape of printed contact fingers from a single 2D image without the need of additional hardware using deep ***,a workflow for the generation of training data,which involves the creation of image pairs from a 2D microscope and a 3D confocal laser scanning microscope(CLSM)to accurately represent solar cell fingers,is *** model training,the predicted height maps are compared with the ground truth height maps,and the robustness of the model with respect to a paste variation and screen parameter variation is *** results confirm the feasibility and reliability of deep learning-based 3D shape estimation,extending its applicability to new,previously unseen data from screen-printed contact *** a structural similarity index(SSIM)score of 0.76,a strong correlation between the estimated and ground truth height maps is *** summary,our deep learning-based approach for height map estimation offers an effective and reliable solution for fast inline detection and analysis of the cross-sectional area of the printed contact fingers.

关键词： Deep Learning Front-side metallization Image2Heigth Solar cell Screen-printing

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