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 Research on Human Erythrocyte’s Threshold Free Energy for Hemolysis and Damage from Coupling Effect of Shear and Impact Based on Immersed Boundary-Lattice Boltzmann Method

2020 ◽  
Vol 2020 ◽  
pp. 1-7
Author(s):  
Zhong Yun ◽  
Chuang Xiang ◽  
Liang Wang
Keyword(s):  
Free Energy ◽  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Coupling Effect ◽  
Threshold Value ◽  
Blood Pump ◽  
Immersed Boundary ◽  
Threshold Limit ◽  
Spring Network Model ◽  
Boltzmann Method

Researches on the principle of human red blood cell’s (RBC) injuring and judgment basis play an important role in decreasing the hemolysis in a blood pump. In the current study, the judgment of hemolysis in a blood pump study was through some experiment data and empirical formula. The paper forms a criterion of RBC’s mechanical injury in the aspect of RBC’s free energy. First, the paper introduces the nonlinear spring network model of RBC in the frame of immersed boundary-lattice Boltzmann method (IB-LBM). Then, the shape, free energy, and time needed for erythrocyte to be shorn in different shear flow and impacted in different impact flow are simulated. Combining existing research on RBC’s threshold limit for hemolysis in shear and impact flow with this paper’s, the RBC’s free energy of the threshold limit for hemolysis is found to be 3.46 × 10 − 15  J. The threshold impact velocity of RBC for hemolysis is 8.68 m/s. The threshold value of RBC can be used for judgment of RBC’s damage when the RBC is having a complicated flow of blood pumps such as coupling effect of shear and impact flow. According to the change law of RBC’s free energy in the process of being shorn and impacted, this paper proposed a judging criterion for hemolysis when the RBC is under the coupling effect of shear and impact based on the increased free energy of RBC.

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.

An Ultrasonic Knife System for MEMS Packaging

2012 ◽  
Vol 190-191 ◽  
pp. 23-27
Author(s):  
Jin Sha ◽  
Zhi Yuan Yao ◽  
Yang Jiao
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
High Temperature ◽  
High Frequency ◽  
Ultrasonic Transducer ◽  
The Finite Element Method ◽  
Structure Amplitude ◽  
High Frequency Vibration ◽  
Mems Packaging ◽  
The Impact

This paper proposes an ultrasonic knife system for MEMS packaging. The ultrasonic knife system is consisted of an ultrasonic transducer, a cutter and a gripper feeder. The ultrasonic transducer engenders high frequency vibration, which lead to the resonance of the structure. Amplitude transformer can magnify the amplitude. By the impact and collision of the cutter, the material can be cut through, and the high temperature created by high-frequency vibration can do the welding. The structure is designed and optimized by the finite element method, and a model machine is produced. According to the experimental results, the ultrasonic knife system has the virtues of high cutting force and better wedding feature, which are suitable for MEMS packaging.

On Vibrational and Dynamic Characteristics of Engines with Deactivated Cylinders

2020 ◽  
pp. 26-34
Author(s):  
A.I. Yamanin
Keyword(s):  
Dynamic Characteristics ◽  
High Frequency ◽  
Low Frequency ◽  
Vibration Velocity ◽  
Toxic Substances ◽  
Vibration Displacement ◽  
Engine Torque ◽  
High Frequency Vibration ◽  
Low Frequency Vibration ◽  
Loading Modes

The article examines some features of dynamics of engines with shut-off cylinders. This technology can promote reduction of fuel consumption and emission of toxic substances with exhaust fumes at partial speed and loading modes. However, the dynamics of such engines have hardly been considered in previous works. Using calculations (solid state modeling, simulation of motion using software for studying dynamics of mechanisms, as well as the finite element method), the indicators of uniformity of stroke and torque, vibration displacement and vibration velocity of various points of the structure at low- and high-frequency vibration are determined. It is shown that when deactivating a different number of cylinders, the uniformity of the engine torque worsens (to a varying degree) and the load on the crankshaft bearings increases. The average quadratic values of vibration velocity of the bearings at low-frequency vibration and the vibration velocity of the lateral walls of the housing parts at high-frequency vibration increases as well. While engines with deactivated cylinders definitely have advantages in efficiency and environmental performance, they do not improve vibrational and dynamic characteristics, which is particularly evident at low rotational speeds of the shaft and at small loads.

Impacts of using wide bandgap transistors on electronics and motors

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Mathieu Gerber ◽  
Guillaume Callerant ◽  
Christophe Espanet ◽  
Farid Meibody-Tabar ◽  
Noureddine Takorabet
Keyword(s):  
High Frequency ◽  
High Speed ◽  
Wide Bandgap ◽  
Switching Frequency ◽  
Switching Speed ◽  
Content Type ◽  
Parasitic Element ◽  
Fast Switching ◽  
Electronic Model ◽  
The Impact

Purpose The purpose of this paper is to study the high-frequency impacts of fast switching wide-bandgap transistors on electronic and motor designs. The high-frequency power converters, dedicated to driving high-speed motors, require specific models to design predictively electronic and motors. Design/methodology/approach From magnetic and electric models, the high-frequency parasitic elements for both electronics and motor are determined. Then, high-frequency circuit models accounting for of parasitic element extractions are built to study the wide bandgap transistors commutations and their impacts on motor windings. Findings The results of the models, for electronics and motors, are promising. The high-frequency commutation cell study is used to optimize the layouts and to improve the commutation behaviours and performances. The impact of the switching speed is highlighted on the winding voltage susceptibility. Then, the switching frequency and commutation rapidity can be both optimized to increase the performance of motor and electronics. The electronic model is validated by experimentations. Research limitations/implications The method can be only applied to the existing motor and electronic designs. It is not taken into account in an automized global high-frequency optimizer. Originality/value Helped by magnetic and electric FEA calculations where the parasitic element extractions are performed. The switching frequency and commutation rapidity can be both optimized to increase the performance of motor and electronics.

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.

Crucial Factors Analysis of 5×5 Grid Flow-Induced Vibration Test

2017 ◽  
Author(s):  
C. Z. Zhang ◽  
J. Ding ◽  
Y. X. Zheng ◽  
F. J. Gan ◽  
S. J. Gong ◽  
...  
Keyword(s):  
Fuel Assembly ◽  
Flow Rate ◽  
High Frequency ◽  
Vibration Velocity ◽  
Small Scale ◽  
Laser Vibrometer ◽  
Flowing Water ◽  
Flow Induced Vibration ◽  
High Frequency Vibration ◽  
Test Assembly

5×5 small-scale test fuel assembly was manufactured to carry out flow-induced vibration tests, aiming to obtain the vibration responses of new designed grid subjected to axial-flowing water. This test was carried out in a hydraulic loop with the maximum flow rate of 65 m3/h and room temperature and pressure. Laser vibrometer was used to measure the vibrating velocity of grid straps. The vibration peaks were generally distributed in three domains of the frequency spectrum. The first domain is from zero to decades of Hz, in which the vibration may be turbulence-buffeting-induced test assembly vibration as an integer entity. The second domain is from decades to hundreds of Hz, in which the vibration may also be test assembly vibration as an integer entity due to turbopump-induced pressure wave. The third domain is above 1000Hz, in which the vibration may be local strap vibration mainly due to vortex shedding along the edges of the straps. Series of tests were accomplished to figure out the characteristics of the trend of maximum high-frequency vibration velocity and related frequency with increasing flow rate. The high-frequency vibration characteristics of the grid in axial-flowing water are crucial for the fuel assembly designers when evaluating the anti-abrasion performance of fuel rods under reactor flow rate conditions.

scholarly journals Numerical modeling of the process of high-frequency vibration extraction of sheet piles in conditions of water-saturated dusty-sandy and silt-loam soil

2021 ◽  
Vol 18 (2) ◽  
pp. 94-101
Author(s):  
V. M. Polunin ◽  
◽  
I. K. Lobov ◽  
A. V. Gurskiy ◽  
◽  
...  
Keyword(s):  
High Frequency ◽  
Field Experiments ◽  
Calculated Data ◽  
Vibration Velocity ◽  
Sheet Pile ◽  
Influence Zone ◽  
Work Production ◽  
Loam Soil ◽  
Water Saturated ◽  
The Impact

The most common excavation walls are sheet piles, which are often sunk by vibration machines. In conditions of big thickness of water-saturated dispersed soils, one of the regulated safety criteria for the use of dynamic technology is the magnitude of soil vibrations and the structures that come to be located in the influence zone. The article presents the measured vibrations of the soil near the pile space in the process of vibration extraction of sheet piles. A characteristic oscillogram of vibration velocity with the characteristic stages of work production is added. Spectral analysis of the impact was performed to assess the prevailing frequency of the impact. The description of the process of numerical simulation of vibration extraction of a pile is given. As for the simulation results, there were obtained calculated oscillograms of the sheet piles located at 1.4 and 2.8 m distance from the sheet pile, and the influence zone was estimated. The calculated data obtained were compared with the results of field experiments.

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.

Vibration monitoring and strength of structural elements taking into account the inertial properties of materials under broadband vibration

2020 ◽  
Author(s):  
О.B. Skvortsov
Keyword(s):  
High Frequency ◽  
Cyclic Strength ◽  
Vibration Monitoring ◽  
Structural Elements ◽  
High Frequency Vibration ◽  
Latent Defects ◽  
Current State ◽  
Properties Of Materials ◽  
High Frequency Vibrations ◽  
The Impact

The paper considers influence of the inertial properties of structural materials on mechanical stresses under high-frequency vibrations. The necessity of considering acceleration estimates when creating vibration monitoring systems focused on the incorporating cyclic strength is proved. The importance of the effects of high-frequency vibration in the local areas of the structural material is noted, taking into account the formation of latent defects and reducing the fatigue limit during gigacycle fatigue. Recommendations are given concerning supplement to the vibration monitoring system, taking into account the decrease in strength under high-frequency vibration when solving problems of diagnostics, forecasting and protection with new innovative solutions. It provides increased reliability of the diagnosis and protection of equipment. In addition to evaluating the current state of the unit based on the results of vibration intensity measuring, the proposed solutions allow additional assessing the degree of wear and taking into account the impact of fatigue processes in the operation of a multi-level automatic protection system of the equipment.

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