scholarly journals Dynamic loading of friction disks in automotive transmissions

2020 ◽  
Vol 317 ◽  
pp. 02002
Author(s):  
Alexander Taratorkin ◽  
Victor Derzhanskii ◽  
Igor Taratorkin
Keyword(s):  
High Frequency ◽  
Design Studies ◽  
Plastic Deformations ◽  
High Frequency Oscillations ◽  
Refined Method ◽  
Friction Clutch ◽  
The Stability ◽  
Multicomponent Bodies ◽  
Technical Solutions ◽  
Natural Frequency Spectrum

The article describes a refined method for design studies of friction disks that are integrated into automotive transmissions. A technique is presented to enable finding the natural frequency spectrum exhibited by disks as distributed mass multicomponent bodies. Grounds are given that explicate the necessity to evaluate the stability of oscillations when high-frequency dynamic processes evolve in a nonlinear system after friction clutches are disengaged and when friction clutches are being engaged and wavelike plastic deformations emerge giving rise to overheated spots. The article also sheds light on specific features inherent in the off-design behavior subsequent to the stopping of the clutch booster and pressure unbalance in the clutch booster plenums. The research studies have produced a number of technical solutions that reduce the amplitude of the high-frequency oscillations, which are generated after friction clutches are disengaged and result in plastic deformations of mating surfaces as well as disturbed axial movability of friction disks. They have substantiated the necessity that the relevant linear velocity should be restricted having determined the boundaries of tolerated linear velocities of revolving friction disks. The article presents results of researching into the processes consequent to pressure unbalance in the friction clutch booster plenums and proposes technical solutions to do away with its adverse effects.

Multibody Dynamics and Vibration Analysis for Railcar Wheelset Design Studies

2003 ◽  
Author(s):  
Werner Schiehlen ◽  
Holger Claus
Keyword(s):  
High Frequency ◽  
Bogie Frame ◽  
Design Studies ◽  
Dynamic Analyses ◽  
High Frequency Excitation ◽  
Frequency Excitation ◽  
Railway Passenger ◽  
The Stability ◽  
Dynamics And Vibration ◽  
Unsprung Mass

This paper presents design studies and dynamic analyses of a railway passenger coach. The wheelset excitations are deterministic due to polygonalization generating noise in ICE passenger coaches and stochastic due to track irregularities. The strength of conventional wheelsets against vibrations due to polygonalized wheels is investigated. Radialelastic wheels reduce the unsprung mass and isolate the bogie frame and carbody from the medium and high frequency excitation caused by the wheel/rail interaction. A parameter optimization of such wheels leads to considerably reduced carbody vibrations. Stability tests are performed for various parameter sets of radialand lateralelastic wheels. The results show that designs with increased bending stiffness and improved parameters are feasible, and guarantee the stability of the wheelset motion as well as a noise reduction.

scholarly journals Problems of mining the prospective coal-bearing areas in Donbas

2019 ◽  
Vol 123 ◽  
pp. 01011 ◽  
Author(s):  
Serhii Nehrii ◽  
Tetiana Nehrii ◽  
Leonid Bachurin ◽  
Hanna Piskurska
Keyword(s):  
Compressive Strength ◽  
Energy Security ◽  
Coal Seams ◽  
Plastic Deformations ◽  
Advanced Technologies ◽  
Secondary Support ◽  
The Stability ◽  
Technical Solutions ◽  
Roof Rocks ◽  
Mine Roadways

The prospective coal-bearing areas of Donbas in Ukraine have been identified. Their development will increase the energy security of Ukraine. It has been suggested that the development of these areas will involve mining the coal seams in a weak roof and floor environment, which are characterized by low compressive strength, lower density and a tendency to plastic deformations. The stability has been assessed of the rocks outcrop on the contour of mine roadways for mines operating in these areas. It has been determined that roof rocks in most of these mines belong to a range of groups from very unstable to moderately stable, and the bottom rocks are, in most cases, prone to swelling. This complicates the intensive prospective areas mining with the use of advanced technologies, as well as secondary support for retained goaf-side gateroads with limited yielding property. The mines have been determined, for which this issue is relevant when mining the seams with further increase in the depth. The mechanism of displacement in the secondary supports and has been exemplified and studied using the numerical method. The obtained results allowed us to substantiate the necessity of developing new technical solutions for the protection of gateroads under conditions of prospective Donbas areas.

scholarly journals Can we use intraoperative high‐frequency oscillations to guide tumor‐related epilepsy surgery?

Epilepsia ◽  
2021 ◽  
Author(s):  
Nicole E. C. Klink ◽  
Willemiek J. E. M. Zweiphenning ◽  
Cyrille H. Ferrier ◽  
Peter H. Gosselaar ◽  
Kai J. Miller ◽  
...  
Keyword(s):  
Epilepsy Surgery ◽  
High Frequency ◽  
High Frequency Oscillations

scholarly journals Delay compensation based controller for rotary electrohydraulic servo system

2021 ◽  
Author(s):  
Zakarya Omar ◽  
Xingsong Wang ◽  
Khalid Hussain ◽  
Mingxing Yang
Keyword(s):  
High Frequency ◽  
Dead Time ◽  
Sliding Mode ◽  
Servo System ◽  
Smith Predictor ◽  
Delay Compensation ◽  
Mechanical Parts ◽  
System Output ◽  
Electrohydraulic Servo System ◽  
The Stability

AbstractThe typical power-assisted hip exoskeleton utilizes rotary electrohydraulic actuator to carry out strength augmentation required by many tasks such as running, lifting loads and climbing up. Nevertheless, it is difficult to precisely control it due to the inherent nonlinearity and the large dead time occurring in the output. The presence of large dead time fires undesired fluctuation in the system output. Furthermore, the risk of damaging the mechanical parts of the actuator increases as these high-frequency underdamped oscillations surpass the natural frequency of the system. In addition, system closed-loop performance is degraded and the stability of the system is unenviably affected. In this work, a Sliding Mode Controller enhanced by a Smith predictor (SMC-SP) scheme that counts for the output delay and the inherent parameter nonlinearities is presented. SMC is utilized for its robustness against the uncertainty and nonlinearity of the servo system parameters whereas the Smith predictor alleviates the dead time of the system’s states. Experimental results show smoother response of the proposed scheme regardless of the amount of the existing dead time. The response trajectories of the proposed SMC-SP versus other control methods were compared for a different predefined dead time.

scholarly journals Performance Evaluation of Heading-and-Winning Machines in the Conditions of Potash Mines

2021 ◽  
Vol 11 (8) ◽  
pp. 3444
Author(s):  
Sergey A. Lavrenko ◽  
Dmitriy I. Shishlyannikov
Keyword(s):  
Energy Efficiency ◽  
Experimental Studies ◽  
Efficiency Coefficient ◽  
Mechanized Method ◽  
Methodological Approaches ◽  
The Stability ◽  
Technical Solutions ◽  
Potash Mine ◽  
Complex Indicators ◽  
Potassium Magnesium

The authors focus on the process of potash ore production by a mechanized method. They show that currently there are no approved procedures for assessing the performance of heading-and-winning machines operating in the conditions of potash mines. This causes difficulties in determining the field of application of heading-and-winning machines, complicates the search for implicit technical solutions for the modernisation of existing models of mining units, prohibits real-time monitoring of the stability of stope-based technological processes and makes it difficult to assess the performance of the services concerning mining enterprises. The work represents an aggregate assessment of the performance of heading-and-winning machines for potash mines by determining complex indicators describing the technological and technical levels of organising the work in stopes. Such indicators are the coefficients of productivity and energy efficiency, respectively. Experimental studies have been carried out in the conditions of the potash mine of the Verkhnekamskoye potassium-magnesium salt deposit to assess the performance of the latest and most productive Ural-20R heading-and-winning machines manufactured in Russia. Using the above methodological approaches, this paper shows that the unsatisfactory technological performance of the studied machine is due to the low productivity of the mine district transport. The average productivity coefficient was 0.29. At the same time, high values of the energy efficiency coefficient show that the productivity of the machine is on par with design conditions.

scholarly journals High-frequency oscillations recorded with surface EEG in neonates with seizures

2021 ◽  
Author(s):  
Lotte Noorlag ◽  
Maryse A. van 't Klooster ◽  
Alexander C. van Huffelen ◽  
Nicole E.C. van Klink ◽  
Manon J.N.L. Benders ◽  
...  
Keyword(s):  
High Frequency ◽  
High Frequency Oscillations ◽  
Surface Eeg
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