scholarly journals Research into Correlation between the Lubrication Mode of Contact Surfaces and Dynamic Parameters of Turbo-Generator Transmissions

2019 ◽  
Vol 2019 ◽  
pp. 1-10
Author(s):  
Marek Kočiško ◽  
Petr Baron ◽  
Monika Telíšková ◽  
Jozef Török ◽  
Anna Bašistová
Keyword(s):  
Acoustic Emission ◽  
High Frequency ◽  
High Speed ◽  
Oil Quality ◽  
The State ◽  
Dynamic Parameters ◽  
High Frequency Vibration ◽  
Turbo Generator ◽  
Friction Mode ◽  
Contact Surfaces

The paper presents the results of an experimental study aimed at assessing the correlation between the measurement of dynamic parameters (vibration, high-frequency vibration, and acoustic emission) and the analysis of friction mode and the state of lubrication of the contact surfaces of two gearboxes in the turbo-generator assembly (high-speed single-body steam turbine—gearbox—generator) with the transmission power of no more than 50 MW. The analysis confirmed the assumption of a significant correlation of the monitored high-frequency vibration signal with the unsatisfactory engagement of the gear teeth. Through vibration analysis, an increased level of the tooth vibration component and vibration multiples with increased acoustic emission were identified in gearbox operation. The gear oil of one of the gearboxes examined showed a loss of additive elements in the real operation of the contact surfaces of the teeth engagement. The trend analysis confirmed the complexity of the monitored transmission operation in terms of the friction mode and the influence of the oil quality on the state of the tooth flank microgeometry.

EFFECT OF A HIGH-FREQUENCY VIBRATION BOUNDARY ON RBC

2018 ◽  
Vol 18 (08) ◽  
pp. 1840032
Author(s):  
ZHONG YUN ◽  
CHUANG XIANG ◽  
LIANG WANG
Keyword(s):  
High Frequency ◽  
High Speed ◽  
Blood Pump ◽  
Vibration Velocity ◽  
Immersed Boundary ◽  
High Frequency Vibration ◽  
Rbc Membrane ◽  
Spring Network Model ◽  
Boltzmann Method ◽  
The Impact

The vibrations in blood pumps were often caused by high speed, suspension structure, viscoelastic implantation environment and other factors in practical application. Red blood cell (RBC) was modeled using a nonlinear spring network model. The immersed boundary-lattice Boltzmann method (IB-LBM) was used to investigate the impact of high-frequency vibration boundary on RBC. To confirm the RBC model, the simulation results of RBC stretching were compared with experimental results. We examined the force acting on RBC membrane nodes; moreover, we determined whether RBC energy was affected by different frequencies, amplitudes, and vibration models of the boundary. Furthermore, we examined whether RBC energy was affected by the distance between the top and bottom boundaries. The energy of RBCs in shear flow disturbed by the vibration boundary was also investigated. The results indicate that larger amplitude (Am), frequency (Fr), and opposite vibration velocity of top and bottom boundary produced a larger force that acted on RBC membrane nodes and larger energy changes in RBCs. The vibration boundary may cause turbulence and alter RBC energy. When the blood pump was designed and optimized, the vibration frequency and amplitude of the blood pump body and impeller should be reduced, the phase of the blood pump body and impeller vibration velocity should be close. To alleviate the free energy of RBCs and to reduce RBC injury in the blood pump, the distance between RBCs and the boundary should not be less than 20[Formula: see text][Formula: see text]m.

scholarly journals Fatigue Performance of the CA Mortar Used in CRTS I Ballastless Slab Track under Simulated Servicing Condition

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2259 ◽  
Author(s):  
Yuchuan Shan ◽  
Shuguang Zheng ◽  
Xuefeng Zhang ◽  
Wei Luo ◽  
Jingda Mao ◽  
...  
Keyword(s):  
Fatigue Test ◽  
High Frequency ◽  
High Speed ◽  
Comfort Level ◽  
Polymer Emulsion ◽  
High Speed Railway ◽  
High Frequency Vibration ◽  
Vibration Load ◽  
Slab Track ◽  
Ca Mortar

The cement and asphalt mortar (CA mortar) used in the China Railway Track System (CRTS) I ballastless slab track may encounter a coupling fatigue effect under the high-frequency vibration, load and high-and-low temperature cycles, and the deterioration under fatigue may happen during service of the high-speed railway. In this study, the performance degradation and its mechanism of the CA mortar with and without polymer emulsion incorporated under the coupling fatigue effects of the high-frequency vibration, load and temperature were studied by using an anti-fatigue testing device specially developed for the CA mortar used in the ballastless slab track of the high-speed railway. The results showed that the deformation capacity of the CA mortar for CRTS I slab ballastless slab track decreased after fatigue test under simulated service environment, presenting a typical brittle characteristic and an obvious reduction of the ductility and toughness. The Scanning Electron Microscopy (SEM) observation and the mercury intrusion porosimetry (MIP) analysis showed that the volume of the macropore decreased whereas that of the micropore increased after the fatigue test. The asphalt in the hardened CA mortar revealed a softening and migration from the bulk paste to fill the pore and make the structure denser and even ooze out of the CA mortar under the high-frequency vibration and high temperature. Through incorporating the polymer emulsion, the anti-fatigue property of the CA mortar was obviously improved, which can prevent the CA mortar from losing its elastic adjustment function too early. Though increase of the strength and elastic modulus for the CA mortar after severe service is beneficial to the stability of train running, the comfort level and safety of the train operation may decline due to the gradual reduction of the ductility & toughness and the gradual loss of the elastic damping adjustment function of the CA mortar between the base concrete slab and the track slab.

scholarly journals High-speed End Milling of Extruded Aluminum Alloys Using Articulated Robot

1999 ◽  
Vol 11 (5) ◽  
pp. 399-403
Author(s):  
Kazunori Shimizu ◽  
◽  
Shin-ichi Matsuoka ◽  
Nobuyuki Yamazaki ◽  
Yoshinari Oki ◽  
...  
Keyword(s):  
Aluminum Alloys ◽  
Cutting Force ◽  
High Frequency ◽  
High Speed ◽  
End Milling ◽  
Small Diameter ◽  
Work Piece ◽  
High Frequency Vibration ◽  
Low Stiffness ◽  
Articulated Robot

This study describes the end milling operation using an articulated robot that is the new machining for extruded aluminum alloys. The most important characteristic of this operation is using the small diameter of endmill and the high-speed spindle in order to reduce a cutting force and improve the low stiffness of an articulated robot. However, the behavior of end milling with super-fast spindle speed for extruded aluminum alloys was still unclear. In this paper, in order to clear it, the basic end milling experiments and structural analysis were done. Consquently, it was proved that the high frequency vibration proper to high-speed end milling had a close relation to the stiffness (natural frequency) of machine tools or work piece, and great affected the cutting force and the cutting surface. On the other hand, it was confirmed that the articulated robot had few effects on the high frequency vibration of end milling because of low stiffness, and that the cutting force was 50 to 70% down compared with the fluting machine. Therefore, it is thought that the end milling using an articulated robot is effective for the improvement of high-speed end milling performance.

scholarly journals Re-Design of Machine Tool Joint Components Based on Polymer Fillings for High-Speed Performance

Materials ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 6913
Author(s):  
Zuzana Murčinková ◽  
Pavel Adamčík ◽  
Jozef Živčák
Keyword(s):  
Acoustic Emission ◽  
High Frequency ◽  
High Speed ◽  
Dynamic Properties ◽  
Hybrid Structure ◽  
Particulate Composites ◽  
High Frequency Signal ◽  
Structural Modifications ◽  
Speed Performance

In this paper, we report the results of an experimental study of a re-design approach using filling polymers and particulate composites with a polymer matrix, thus creating a macroscopic hybrid structure. The re-design is focused on the joint of a textile machine. It is a re-design of already existing machine parts of a joint in order to increase the damping of components, reduce the amplitudes of high-frequency vibrations and acoustic emission for high-speed operation of textile rotors, and to compare individual structural modifications of the rotor housing body and absorber of high-speed textile rotor in a spinning unit with respect to dynamic properties of that measured mechanical system. The experiments included a bump test, determination of logarithmic decrement, measurement of vibration acceleration, a wavelet analysis, and measurement of acoustic emission. When excited by high frequency signal amplitudes up to 5 g, the benefits of polymer filling were manifested by an approximately 50% reduction in amplitude vibrations, a 66% reduction in acoustic emission amplitude, and an 85% reduction of the maximum peak in the acoustic emission FFT spectrum. In the area above 10 g, the stiffness of the component dominated to reduce the magnitude of vibrations.

scholarly journals 1212 Analysis on High Frequency Vibration Characteristic of Passenger-Seat in High Speed Railway Vehicle

2011 ◽  
Vol 2011.20 (0) ◽  
pp. 111-114
Author(s):  
Sotaro SAITO ◽  
Ryuzo HAYASHI ◽  
Masao NAGAI ◽  
Ryohei SHIMAMUNE ◽  
Masahiko MIZUGUCHI ◽  
...  
Keyword(s):  
High Frequency ◽  
High Speed ◽  
Railway Vehicle ◽  
Vibration Characteristic ◽  
High Speed Railway ◽  
High Frequency Vibration ◽  
Passenger Seat

APPLICATION OF THE EARLY DAMAGE DIAGNOSTICS TECHNIQUE TO EXAMINATION OF THE AVIATION PANEL

2019 ◽  
Vol 85 (6) ◽  
pp. 53-63 ◽  
Author(s):  
I. E. Vasil’ev ◽  
Yu. G. Matvienko ◽  
A. V. Pankov ◽  
A. G. Kalinin
Keyword(s):  
Acoustic Emission ◽  
Damage Detection ◽  
High Speed ◽  
Early Stage ◽  
Video Data ◽  
High Speed Video ◽  
Damage Diagnostics ◽  
Subsurface Defect ◽  
Sensitive Coating ◽  
Early Damage

The results of using early damage diagnostics technique (developed in the Mechanical Engineering Research Institute of the Russian Academy of Sciences (IMASH RAN) for detecting the latent damage of an aviation panel made of composite material upon bench tensile tests are presented. We have assessed the capabilities of the developed technique and software regarding damage detection at the early stage of panel loading in conditions of elastic strain of the material using brittle strain-sensitive coating and simultaneous crack detection in the coating with a high-speed video camera “Video-print” and acoustic emission system “A-Line 32D.” When revealing a subsurface defect (a notch of the middle stringer) of the aviation panel, the general concept of damage detection at the early stage of loading in conditions of elastic behavior of the material was also tested in the course of the experiment, as well as the software specially developed for cluster analysis and classification of detected location pulses along with the equipment and software for simultaneous recording of video data flows and arrays of acoustic emission (AE) data. Synchronous recording of video images and AE pulses ensured precise control of the cracking process in the brittle strain-sensitive coating (tensocoating)at all stages of the experiment, whereas the use of structural-phenomenological approach kept track of the main trends in damage accumulation at different structural levels and identify the sources of their origin when classifying recorded AE data arrays. The combined use of oxide tensocoatings and high-speed video recording synchronized with the AE control system, provide the possibility of definite determination of the subsurface defect, reveal the maximum principal strains in the area of crack formation, quantify them and identify the main sources of AE signals upon monitoring the state of the aviation panel under loading P = 90 kN, which is about 12% of the critical load.

Cyclone Bomb hits Southern Brazil in 2020

2020 ◽  
Vol 3 (3) ◽  
Author(s):  
Ricardo Gobato ◽  
Alireza Heidari
Keyword(s):  
High Pressure ◽  
Atmospheric Pressure ◽  
High Speed ◽  
Satellite Images ◽  
The State ◽  
Southern Brazil ◽  
Santa Catarina ◽  
High Area ◽  
South Of Brazil ◽  
Rapid Drop

An “explosive extratropical cyclone” is an atmospheric phenomenon that occurs when there is a very rapid drop in central atmospheric pressure. This phenomenon, with its characteristic of rapidly lowering the pressure in its interior, generates very intense winds and for this reason it is called explosive cyclone, bomb cyclone. With gusts recorded of 116 km/h, atmospheric phenomenon – “cyclone bomb” (CB) hit southern Brazil on June 30, the beginning of winter 2020, causing destruction in its influence over. One of the cities most affected was Chapecó, west of the state of Santa Catarina. The satellite images show that the CB generated a low pressure (976 mbar) inside it, generating two atmospheric currents that moved at high speed. In a northwest-southeast direction, Bolivia and Paraguay, crossing the states of Parana and Santa Catarina, and this draft that hit the south of Brazil, which caused the destruction of the affected states.  Another moving to Argentina, southwest-northeast direction, due to high area of high pressure (1022 mbar). Both enhanced the phenomenon.

Tool wear analysis in high-frequency vibration-assisted drilling of additive manufactured Ti6Al4V alloy

Wear ◽  
2021 ◽  
pp. 203814
Author(s):  
Marco Sorgato ◽  
Rachele Bertolini ◽  
Andrea Ghiotti ◽  
Stefania Bruschi
Keyword(s):  
Tool Wear ◽  
High Frequency ◽  
Ti6al4v Alloy ◽  
High Frequency Vibration ◽  
Wear Analysis
Sign in / Sign up

Export Citation Format

Share Document