Non-Linear Flutter in Fan Stator Vanes With Time Dependent Fixity

2010 ◽  
Author(s):  
R. Srivastava ◽  
J. Panovsky ◽  
R. Kielb ◽  
L. Virgin ◽  
K. Ekici
Keyword(s):  
Natural Frequency ◽  
High Speed ◽  
External Source ◽  
High Amplitude ◽  
Time Dependent ◽  
Test Results ◽  
Turbofan Engines ◽  
Lower Natural Frequency ◽  
Stator Vane

A new mechanism for fan stator vane failure in turbofan engines at high speed and high loading has been identified and reported in this paper. Highly destructive vane failures have been encountered at Honeywell in one of the development fans with composite stator vanes. Measured data indicated nonlinear high amplitude vibratory response in fan stator vanes on stall side of the fan map at high speeds. Analysis showed that under certain vane steady loading vane fixity at hub could change, significantly reducing the vane natural frequency. At lower natural frequency the vane was found to be aeroelastically unstable and calculated response exhibited behavior observed during failure. An engine test was conducted to validate the role of hub fixity in vane failures. Test results showed failure to be a self-excited phenomenon and not driven by an external source of excitation. It was also shown that failures occur in vanes that are not rigidly fixed, validating the role of hub fixity in vane failures. Test results along with the analysis confirm the role of time dependent hub fixity leading to the highly destructive flutter responsible for vane failures.

Nonlinear Flutter in Fan Stator Vanes With Time Dependent Fixity

2011 ◽  
Vol 134 (2) ◽  
Author(s):  
R. Srivastava ◽  
J. Panovsky ◽  
R. Kielb ◽  
L. Virgin ◽  
K. Ekici
Keyword(s):  
Natural Frequency ◽  
High Speed ◽  
External Source ◽  
High Amplitude ◽  
Time Dependent ◽  
Turbofan Engines ◽  
Lower Natural Frequency ◽  
High Speeds ◽  
Stator Vane

A new mechanism for fan stator vane failure in turbofan engines at high speed and high loading has been identified and reported in this paper. Highly destructive vane failures have been encountered at Honeywell in a development fan with composite stator vanes. Measured data indicated nonlinear high amplitude vibratory response in fan stator vanes on the stall side of the fan map at high speeds. Analysis showed that under certain steady loading, vane fixity at the hub could change, significantly reducing the vane natural frequency. At this lower natural frequency, the vane was found to be aeroelastically unstable, and calculated response exhibited characteristics similar to those observed during failure. An engine test conducted to validate the role of hub fixity in vane failures showed the failure to be a self-excited phenomenon and not driven by an external source of excitation. It was also shown that failures occur in vanes that are not rigidly fixed, validating the role of hub fixity in vane failures. Test results along with analysis confirm the role of time dependent hub fixity leading to the highly destructive flutter responsible for vane failures.

Finite Element Modal Analysis of Ball Screws Linear Guide Feed Unit

2013 ◽  
Vol 433-435 ◽  
pp. 67-71 ◽  
Author(s):  
Xiang Rong Xu ◽  
Xian Chun Song ◽  
Hong Kui Jiang ◽  
Yan Feng Li
Keyword(s):  
Finite Element ◽  
Modal Analysis ◽  
Natural Frequency ◽  
High Speed ◽  
Element Model ◽  
Ball Screw ◽  
Test Results ◽  
Cnc Machine ◽  
Linear Guide ◽  
Feed Unit

With the high-speed and high-precision development of CNC machine tool, the vibration problem of ball screws linear guide feed unit has become more and more prominent. The dynamic characteristics was analyzed for ball screws linear guide feed unit, the 3D finite element model was built, the finite element modal analysis was discussed, the natural frequency and vibration modes were obtained, which were compared with the test results. The vibration weaknesses of ball screws linear guide feed unit were found out. The results show that the vibration weaknesses of ball screws linear guide feed unit occur mainly in the ball screws and its connection part with the worktable, its natural frequency are affected by its supporting pattern, and more close to the test results compared with those of ball screw feed unit without considering linear guide, which provide theoretical basis for the structure optimization of ball screws linear guide feed unit.

A Statistical Study of Process Variables to Optimize a High Speed Curtain Coater: Part I

TAPPI Journal ◽  
2009 ◽  
Vol 8 (1) ◽  
pp. 20-26 ◽  
Author(s):  
PEEYUSH TRIPATHI ◽  
MARGARET JOYCE ◽  
PAUL D. FLEMING ◽  
MASAHIRO SUGIHARA
Keyword(s):  
Boundary Layer ◽  
Experimental Design ◽  
High Speed ◽  
Statistical Study ◽  
Process Variables ◽  
High Speeds ◽  
The Stability ◽  
Air Removal ◽  
Removal System

Using an experimental design approach, researchers altered process parameters and material prop-erties to stabilize the curtain of a pilot curtain coater at high speeds. Part I of this paper identifies the four significant variables that influence curtain stability. The boundary layer air removal system was critical to the stability of the curtain and base sheet roughness was found to be very important. A shear thinning coating rheology and higher curtain heights improved the curtain stability at high speeds. The sizing of the base sheet affected coverage and cur-tain stability because of its effect on base sheet wettability. The role of surfactant was inconclusive. Part II of this paper will report on further optimization of curtain stability with these four variables using a D-optimal partial-facto-rial design.

LANDSLIDE RISK MANAGEMENT IN THE COASTAL ZONE OF THE KUIBYSHEV RESERVOIR DUE THE DESIGN OF HIGH-SPEED LINE "MOSCOW-KAZAN"

2017 ◽  
Author(s):  
Nikolai Petrov ◽  
Nikolai Petrov ◽  
Inna Nikonorova ◽  
Inna Nikonorova ◽  
Vladimir Mashin ◽  
...  
Keyword(s):  
High Speed ◽  
Computational Models ◽  
Stable State ◽  
Landslide Risk ◽  
Kuibyshev Reservoir ◽  
Stepped Surface ◽  
The Stability ◽  
Landslide Slope ◽  
The Village

High-speed railway "Moscow-Kazan" by the draft crosses the Volga (Kuibyshev reservoir) in Chuvashia region 500 m below the village of New Kushnikovo. The crossing plot is a right-bank landslide slope with a stepped surface. Its height is 80 m; the slope steepness -15-16o. The authors should assess the risk of landslides and recommend anti-landslide measures to ensure the safety of the future bridge. For this landslide factors have been analyzed, slope stability assessment has been performed and recommendations have been suggested. The role of the following factors have been analyzed: 1) hydrologic - erosion and abrasion reservoir and runoff role; 2) lithologyc (the presence of Urzhum and Northern Dvina horizons of plastically deformable rocks, displacement areas); 3) hydrogeological (the role of perched, ground and interstratal water); 4) geomorphological (presence of the elemental composition of sliding systems and their structure in the relief); 5) exogeodynamic (cycles and stages of landslide systems development, mechanisms and relationship between landslide tiers of different generations and blocks contained in tiers). As a result 6-7 computational models at each of the three engineering-geological sections were made. The stability was evaluated by the method “of the leaning slope”. It is proved that the slope is in a very stable state and requires the following measures: 1) unloading (truncation) of active heads blocks of landslide tiers) and the edge of the plateau, 2) regulation of the surface and groundwater flow, 3) concrete dam, if necessary.

Development Of Spine Mobility And Muscle Elasticity Through The Pilates Method

2019 ◽  
pp. 71-77
Author(s):  
Irene-Teodora Nica
Keyword(s):  
Target Group ◽  
Test Results ◽  
Muscle Elasticity ◽  
Spine Mobility ◽  
Pilates Method ◽  
Anterior Plane

The present study aims to emphasize the role of pilates method in the improvement of the mobility of the spine in the anterior plane and the elasticity of the posterior muscles of the thigh. In this purpose, we have developed a set of appropriate exercises destined to obtain improved results of the spine mobility and muscle elasticity. Subsequent, we applied the exercises to a target group of woman and presented the comparation between the initial and final results. The interpretation of the mobility and elasticity test results are reported in the conclusions of the present study.

scholarly journals High-Speed Video Analysis of the Process Stability in Plasma Spraying

2021 ◽  
Author(s):  
K. Bobzin ◽  
M. Öte ◽  
M. A. Knoch ◽  
I. Alkhasli ◽  
H. Heinemann
Keyword(s):  
Plasma Spraying ◽  
High Speed ◽  
Plasma Jet ◽  
Plasma Jets ◽  
Time Dependent ◽  
Acquisition Time ◽  
Fast Fourier Transformation ◽  
Frequency Spectra ◽  
Dependent Signal ◽  
The Stability

AbstractIn plasma spraying, instabilities and fluctuations of the plasma jet have a significant influence on the particle in-flight temperatures and velocities, thus affecting the coating properties. This work introduces a new method to analyze the stability of plasma jets using high-speed videography. An approach is presented, which digitally examines the images to determine the size of the plasma jet core. By correlating this jet size with the acquisition time, a time-dependent signal of the plasma jet size is generated. In order to evaluate the stability of the plasma jet, this signal is analyzed by calculating its coefficient of variation cv. The method is validated by measuring the known difference in stability between a single-cathode and a cascaded multi-cathode plasma generator. For this purpose, a design of experiment, covering a variety of parameters, is conducted. To identify the cause of the plasma jet fluctuations, the frequency spectra are obtained and subsequently interpreted by means of the fast Fourier transformation. To quantify the significance of the fluctuations on the particle in-flight properties, a new single numerical parameter is introduced. This parameter is based on the fraction of the time-dependent signal of the plasma jet in the relevant frequency range.

Role of secondary phase particles in fatigue behavior of high-speed railway gearbox material

2020 ◽  
Vol 131 ◽  
pp. 105336 ◽  
Author(s):  
Yinan Jiao ◽  
Yifan Zhang ◽  
Shiqing Ma ◽  
Deli Sang ◽  
Yang Zhang ◽  
...  
Keyword(s):  
High Speed ◽  
Fatigue Behavior ◽  
Secondary Phase ◽  
High Speed Railway

scholarly journals Towards a Glass New World: The Role of Ion-Exchange in Modern Technology

2021 ◽  
Vol 11 (10) ◽  
pp. 4610
Author(s):  
Simone Berneschi ◽  
Giancarlo C. Righini ◽  
Stefano Pelli
Keyword(s):  
Ion Exchange ◽  
Communication Networks ◽  
High Speed ◽  
High Performance ◽  
Low Cost ◽  
Modern Technology ◽  
Historical Background ◽  
Wide Range ◽  
Happy Marriage

Glasses, in their different forms and compositions, have special properties that are not found in other materials. The combination of transparency and hardness at room temperature, combined with a suitable mechanical strength and excellent chemical durability, makes this material indispensable for many applications in different technological fields (as, for instance, the optical fibres which constitute the physical carrier for high-speed communication networks as well as the transducer for a wide range of high-performance sensors). For its part, ion-exchange from molten salts is a well-established, low-cost technology capable of modifying the chemical-physical properties of glass. The synergy between ion-exchange and glass has always been a happy marriage, from its ancient historical background for the realisation of wonderful artefacts, to the discovery of novel and fascinating solutions for modern technology (e.g., integrated optics). Getting inspiration from some hot topics related to the application context of this technique, the goal of this critical review is to show how ion-exchange in glass, far from being an obsolete process, can still have an important impact in everyday life, both at a merely commercial level as well as at that of frontier research.

scholarly journals Design and Fabrication of a High-Speed Atomic Force Microscope Scan-Head

Sensors ◽  
2021 ◽  
Vol 21 (2) ◽  
pp. 362
Author(s):  
Luke Oduor Otieno ◽  
Bernard Ouma Alunda ◽  
Jaehyun Kim ◽  
Yong Joong Lee
Keyword(s):  
Atomic Force Microscope ◽  
Natural Frequency ◽  
High Speed ◽  
Contact Mode ◽  
Ongoing Process ◽  
Atomic Force ◽  
Constant Height ◽  
Mode Tracking

A high-speed atomic force microscope (HS-AFM) requires a specialized set of hardware and software and therefore improving video-rate HS-AFMs for general applications is an ongoing process. To improve the imaging rate of an AFM, all components have to be carefully redesigned since the slowest component determines the overall bandwidth of the instrument. In this work, we present a design of a compact HS-AFM scan-head featuring minimal loading on the Z-scanner. Using a custom-programmed controller and a high-speed lateral scanner, we demonstrate its working by obtaining topographic images of Blu-ray disk data tracks in contact- and tapping-modes. Images acquired using a contact-mode cantilever with a natural frequency of 60 kHz in constant deflection mode show good tracking of topography at 400 Hz. In constant height mode, tracking of topography is demonstrated at rates up to 1.9 kHz for the scan size of 1μm×1μm with 100×100 pixels.

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