Experimental and Numerical Analysis of Geometrical Induced Mistuning

2015 ◽  
Author(s):  
Frederik Popig ◽  
Peter Hönisch ◽  
Arnold Kühhorn
Keyword(s):  
Vibration Analysis ◽  
Optical Measurement ◽  
Measurement Data ◽  
Point Of View ◽  
Optical Measurements ◽  
Experimental Point ◽  
Fe Model ◽  
Mode Localization ◽  
Blisk Blade ◽  
The Impact

The application of high pressure compressor (HPC) rotors manufactured as blisk (Blade Integrated Disk) is ever-expanding in modern jet engine designs. Despite the major advantages of less mass and higher efficiency, the most challenging problem is lower mechanical damping due to the loss of damping between blades root’s and the disk. Mistuning is induced by material inhomogeneities, manufacturing tolerances or wear during use and leads to amplitude magnification and mode localization. From the experimental point of view mistuning can be evaluated via experimental vibration analysis in terms of frequency deviations. Furthermore optical measurements can be evaluated in terms of geometrical deviations between the real and designed geometry. From the structural point of view a mistuned blisk model can be obtained by morphing the nodes of the geometrical tuned FE model or by performing blade individual stiffness mistuning due to modification of Young’s modulus. The following work is focused on the numerical prediction of mistuned blisk vibrations. Therefore, the research blisk of the 4 stage research compressor, manufactured as job-production, is analyzed. For this research blisk optical measurement data as well as experimentally obtained frequency patterns are available. In a first part mistuning identification in terms of experimental vibration analysis and Proper Orthogonal Decomposition of the geometrical deviations is presented. In a second part mistuning modeling in terms of stiffness mistuning and geometrical mistuning is applied to the tuned FE-model and the numerical results are evaluated against experimental data regarding accuracy. Furthermore, the impact of geometrical deviations on mistuning is analyzed.

scholarly journals Bending Response and Energy Absorption of Closed-Hat-Section Beams

2016 ◽  
Vol 10 (11) ◽  
pp. 225
Author(s):  
Hafizan Hashim ◽  
Amir Radzi Ab Ghani ◽  
Wahyu Kuntjoro
Keyword(s):  
Energy Absorption ◽  
Plate Thickness ◽  
Point Of View ◽  
Critical Parameters ◽  
Research Report ◽  
Experimental Point ◽  
Fe Model ◽  
Research Information ◽  
Foam Filling ◽  
Energy Absorbers

Many articles on bending collapse but not limited to closed-hat-section beams have been reported mainly from experimental point of view but less in simulation-based approach. Detailed investigation on critical parameters of closed-hat-section beams to examine their energy absorption capability is also less found in the literature. This paper presents the procedure for development and validation of a finite element (FE) model of a closed-hat-section beam under quasi static three-point bending using an explicit nonlinear FE technique. Developed FE models were validated through comparison with existing and present experiment results. Firstly, the existing models were rebulit via present modeling technique using informations provided in the relevant research report. Simulation results of rebuilt model were compared with existing results for verification and validation. Next, to further validate the present model, actual physical experiment replicating the FE model was set up for comparison of results. Validated models were then used in parametric studies in order to investigate the effect of some critical parameters such as plate thickness, flange and web width, and foam filler. Results show that the wall thickness, web width, and filler have direct effect on bending stiffness. Foam filling indicated significant enhancement on the crush and energy absorption of closed-hat-section beams. This study provides detail procedures and research information which will facilitate improvisation of current design as well as the design of foam filled closed-hat-section beams as energy absorbers in impact applications.

scholarly journals Impact of Hydrogen Injection on Natural Gas Measurement

Energies ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 8461
Author(s):  
Marco Dell’Isola ◽  
Giorgio Ficco ◽  
Linda Moretti ◽  
Jacek Jaworski ◽  
Paweł Kułaga ◽  
...  
Keyword(s):  
Natural Gas ◽  
Thermodynamic Properties ◽  
Calorific Value ◽  
Experimental Tests ◽  
Point Of View ◽  
Experimental Point ◽  
Theoretical Point ◽  
Primary Role ◽  
Gas Measurements ◽  
The Impact

Hydrogen is increasingly receiving a primary role as an energy vector in ensuring the achievement of the European decarbonization goals by 2050. In fact, Hydrogen could be produced also by electrolysis of water using renewable sources, such as photovoltaic and wind power, being able to perform the energy storage function, as well as through injection into natural gas infrastructures. However, hydrogen injection directly impacts thermodynamic properties of the gas itself, such as density, calorific value, Wobbe index, sound speed, etc. Consequently, this practice leads to changes in metrological behavior, especially in terms of volume and gas quality measurements. In this paper, the authors present an overview on the impact of hydrogen injection in natural gas measurements. In particular, the changes in thermodynamic properties of the gas mixtures with different H2 contents have been evaluated and the effects on the accuracy of volume conversion at standard conditions have been investigated both on the theoretical point of view and experimentally. To this end, the authors present and discuss the effect of H2 injection in gas networks on static ultrasonic domestic gas meters, both from a theoretical and an experimental point of view. Experimental tests demonstrated that ultrasonic gas meters are not significantly affected by H2 injection up to about 10%.

scholarly journals Study of Shiny Film Coating on Multi-Fluid Flows of a Rotating Disk Suspended with Nano-Sized Silver and Gold Particles: A Comparative Analysis

Coatings ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 422 ◽  
Author(s):  
Rahmat Ellahi ◽  
Ahmed Zeeshan ◽  
Farooq Hussain ◽  
Tehseen Abbas
Keyword(s):  
Spin Coating ◽  
Fluid Flows ◽  
Rotating Disk ◽  
Film Coating ◽  
Point Of View ◽  
Experimental Point ◽  
Silver Alloy ◽  
Current Effort ◽  
Gold Particles ◽  
The Impact

The current effort is devoted to investigate the shiny thin film with a metallic tactile covering of nanoparticles over the surface of a rotating disk. To decorate, glowing silver and gold particles were chosen. Four illustrative base liquids, namely (i) ethanol, (ii) methanol, (iii) ethylene-glycol, and (iv) water were considered with different geometries, which have great importance in industrial usage. An emphasis on comparative multi nanofluid analysis was used to make a sound judgment on which one of the fluids best suited the metallic glittering process of spin coating. The film thickness process highly depends on the process of evaporation, which takes some time to settle on the disk’s surface. It was found that of the base fluids, the best choices were ethanol alloys with silver. Hence, one can conclude that from an experimental point of view, if silver alloy is used for coating, then only those liquids can be considered that exhibit ethanol-like properties. The impact of pertinent parameters with different aspects are graphically illustrated in each case.

Mistuning Identification Approach With Focus on High-Speed Centrifugal Compressors

2018 ◽  
Vol 141 (3) ◽  
Author(s):  
Robby Weber ◽  
Arnold Kühhorn
Keyword(s):  
Experimental Data ◽  
High Speed ◽  
Common Knowledge ◽  
Optical Measurements ◽  
Fe Model ◽  
Blade Vibration ◽  
Mode Localization ◽  
Characteristic Quantity ◽  
Calculation Results ◽  
Geometric Deviations

Blade vibrations are one of the main cost drivers in turbomachinery. Computational blade vibration analysis facilitates an enormous potential to increase the productivity in the design of bladed components. Increasing computing power as well as improved modeling and simulation methods leads to comprehensive calculation results. This allows for a more precise prediction and assessment of experimental data. Usually, in the field of turbomachinery, identical blades are assumed to lower the required computational resources. However, mistuning is unavoidable, since small deviations due to the manufacturing process will lead to slightly different blade behavior. Potential effects such as mode localization and amplification can be treated statistically and have been thoroughly studied in the past. Since then, several reduced order models (ROMs) have been invented in order to calculate the maximum vibration amplitude of a fleet of mistuned blisks. Most commonly, mistuning is thereby modeled by small material deviations from blade to blade, e.g., Young's modulus or density. Nowadays, it is common knowledge that the level of manufacturing imperfection (referred as level of mistuning) significantly influences mode localization as well as vibration amplification effects. Optical measurements of the geometric deviations of manufactured blades and converting to a high-fidelity finite element (FE) model make huge progress. However, to the knowledge of the authors, there is no reliable method that derives a characteristic quantity from the geometric mistuning, that fits into the mentioned statistically approaches. Therefore, experimental data are needed to quantify the level of mistuning. Several approaches, which isolate blade individual parameters, are used to identify the dynamic behavior of axial compressors and turbines. These methods can be applied to medium-speed centrifugal turbine wheels but tend to fail to evaluate high-speed compressor with splitter blades. This paper briefly presents the original approach and discusses the reasons for failure. Thereafter, a new approach is proposed. Finally, the level of mistuning and important quantities to perform a statistical evaluation of a high-speed compressor is shown.

scholarly journals Experimental Research on the Behaviour of Metal Active Gas Tailor Welded Blanks during Single Point Incremental Forming Process

Metals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 198
Author(s):  
Valentin Oleksik ◽  
Dan Dobrota ◽  
Sever-Gabriel Racz ◽  
Gabriela Petruta Rusu ◽  
Mihai Octavian Popp ◽  
...  
Keyword(s):  
Optical Measurement ◽  
Incremental Forming ◽  
Single Point ◽  
Welding Process ◽  
Force Transducer ◽  
Point Of View ◽  
Experimental Point ◽  
Single Point Incremental Forming ◽  
Forming Process ◽  
Tailor Welded Blanks

The present paper aims to study the behaviour of Metal Active Gas (MAG) tailor welded blanks during the single point incremental forming process (SPIF) from an experimental point of view. The single point incremental forming process was chosen for manufacturing truncated cone and truncated pyramid shaped parts. The same material (S355) and the same thickness (0.9 mm) were selected for the joining of blank sheets because the main goal of the paper was to study the influence of the MAG welding process throughout the SPIF process. A Kuka robot, equipped with a force transducer and an optical measurement system were used for manufacturing and evaluating the parts by SPIF. The selected output data were major and minor strain, thickness reduction, forces and springback at the SPIF process. Another line test was performed to evaluate the formability in SPIF. The main conclusion of the paper is that during the SPIF process, fractures occur in one side welded blanks even at moderate wall angles, while in the case of double side welded blanks there is a decrease of formability but parts can still be produced at moderate angles (55 degrees) without any problems.

Impact of Wide-Base Tires on Pavements: A National Study

2018 ◽  
Vol 2672 (40) ◽  
pp. 186-196 ◽  
Author(s):  
Imad L. Al-Qadi ◽  
Jaime A. Hernandez ◽  
Angeli Gamez ◽  
Mojtaba Ziyadi ◽  
Osman Erman Gungor ◽  
...  
Keyword(s):  
Life Cycle ◽  
Permanent Deformation ◽  
Fatigue Cracking ◽  
Point Of View ◽  
Environmental Benefits ◽  
National Study ◽  
Fe Model ◽  
Pavement Structures ◽  
Pavement Damage ◽  
The Impact

This paper summarizes a multi-year effort comparing the new-generation wide-base tires (NG-WBT) and dual-tire assembly from a holistic point of view. The tires were compared considering not only pavement damage but also environmental impact. Numerical modeling, prediction methods, experimental measurements, and life-cycle assessment were combined to provide recommendations about the use of NG-WBT. A finite element (FE) approach considering variables that are usually omitted in the conventional analysis of flexible pavement was used for modeling pavement structures combining layer thickness, material properties, tire load, tire-inflation pressure, and pavement type (interstate and low volume). A prediction tool, ICT-Wide, was developed based on an artificial neural network to obtain critical pavement responses in cases excluded from the FE analysis matrix. Based on the bottom-up fatigue cracking, permanent deformation, and international roughness index, the life-cycle energy consumption, cost, and green-house gas emissions were estimated. To make this research useful for state departments of transportation and practitioners, a modification to AASHTOware is proposed to account for NG-WBT. The revision is based on two adjustment factors, one accounting for the discrepancy between the AASHTOware approach and the FE model of this study, and the other addressing the impact of NG-WBT. Although greater pavement damage may result from NG-WBT, for the analyzed cases, the extra pavement damage may be outweighed by the environmental benefits when NG-WBT market penetration is considered.

scholarly journals The impact of environmental factors on the measurement of the normalized difference vegetation index

2012 ◽  
pp. 141-147
Author(s):  
Attila Dobos ◽  
Róbert Víg ◽  
János Nagy
Keyword(s):  
Relative Humidity ◽  
Chlorophyll Content ◽  
Vegetation Index ◽  
Optical Measurement ◽  
Meteorological Data ◽  
Nitrogen Supply ◽  
Optical Measurements ◽  
Measurement Height ◽  
Weather Parameters ◽  
The Impact

The level of nitrogen supply of a plant population can be quickly measured with non-destructive optical measurement devices and the differentiated determination of nitrogen shortage and the replenishment of nitrogen can also be carried out. The level of nitrogen supply is based on the fact that the chlorophyll content of crops is in close correlation with nitrogen content and that the amount of chlorophyll can be easily measured on the basis of the light absorption of chlorophyll molecules. The successfulness of optical measurements can be influenced by the change of weather  parameters; therefore, it is important to know the correlations between measurement results and weather parameters when it comes to practical use.The GreenSeeker Model 505 measurement device determines the relative chlorophyll content in the form of the Normalized DifferenceVegetation Index (NDVI) calculated on the basis of the intensity of the reflected red and infrared rays of light from the crop population. The measurements were performed in alfalfa population with 10 replications at five measurement heights and four measurement times. The weather parameters were measured by a weather station located in the middle of the alfalfa population and the correlations between the meteorological data and the NDVI values were examined. During the statistical evaluation of the results, it was established that the NDVI measurement is primarily influenced by the relative humidity of the air, secondly by air temperature and thirdly by wind speed. Relative humidity was in strong correlation with the NDVI values which were also influenced by the measurement height and time. Regression was not significant in the case of 20 cm  measurement height, but the measurements above 40 cm height showed significant correlations. The correlation was shown to be strong at each measurement time, but the influence of humidity was the lowest at 11:00 and 14:00. 

The Geosciences Applied to Lunar Exploration

1962 ◽  
Vol 14 ◽  
pp. 169-257 ◽  
Author(s):  
J. Green
Keyword(s):  
Lunar Surface ◽  
Probable Mechanism ◽  
Point Of View ◽  
Lunar Exploration ◽  
Geological Model ◽  
Apply Geophysics ◽  
Surface Features ◽  
The Impact

The term geo-sciences has been used here to include the disciplines geology, geophysics and geochemistry. However, in order to apply geophysics and geochemistry effectively one must begin with a geological model. Therefore, the science of geology should be used as the basis for lunar exploration. From an astronomical point of view, a lunar terrain heavily impacted with meteors appears the more reasonable; although from a geological standpoint, volcanism seems the more probable mechanism. A surface liberally marked with volcanic features has been advocated by such geologists as Bülow, Dana, Suess, von Wolff, Shaler, Spurr, and Kuno. In this paper, both the impact and volcanic hypotheses are considered in the application of the geo-sciences to manned lunar exploration. However, more emphasis is placed on the volcanic, or more correctly the defluidization, hypothesis to account for lunar surface features.

МАРКЕТИНГОВІ АСПЕКТИ ФУНКЦІОНУВАННЯ ЛІТЕРАТУРНИХ КОНКУРСІВ ТА ПРЕМІЙ

2020 ◽  
pp. 90
Author(s):  
O. Bondar
Keyword(s):  
Publishing House ◽  
Target Audience ◽  
Point Of View ◽  
Information Support ◽  
Literary Field ◽  
Non Profit ◽  
Functional Aspects ◽  
The Media ◽  
Literary Prizes ◽  
The Impact

<p><em>In this study, I have collected and summarized the functional aspects of a literary prize, contest, and rating, which indicate their affiliation with the marketing complex of the publishing house for the first time. For this purpose, I have analyzed and summarized the common concepts of the functioning of literary prizes and contests as advertising tools for publishing activity. Because the previous studies are only focused on the fact of the impact of the prize on the promotion of editions but do not explain it, these aspects have been considered and introduced by me from the book production’s point of view. I investigated that the prizes and the contests in the literary field are effective marketing tools, which meet many publisher’s needs at the same time and can be considered a non-profit form of capital. I have reviewed the works of other authors, who accept that the economic success of the book is rising if the author is a winner of the literary prize or contest. I have found out that the book prize activates the demand for the book, and the literary contest is a tool to track the reader’s reaction to a future publication. In this way, literary prizes and contests can be considered as a way of conducting a marketing dialogue with the target audience. I have focused on the information support of literary national and international prizes and contests by the media, which attracts attention to the book and forms the reader’s interest. The literary prizes and contests are also considered as a way of exploring trends and their changes, familiarization the popular genres among the target audience and fixation the current choice of modern readers. Literary prizes and contests motivate the authors to improve their literary excellence, are the source of new authors and works, and assist in increasing sales of books. However, further research is recommended.</em></p><strong><em>Key words:</em></strong><em> book prize, book rating, literary contest, literary prize, functions of the literary prizes.</em>

High-Tc superconductors from the experimental point of view

1988 ◽  
Vol 156 (9) ◽  
pp. 117-135 ◽  
Author(s):  
L.P. Gor'kov ◽  
N.B. Kopnin
Keyword(s):  
Point Of View ◽  
Experimental Point
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