Whirl of High-Speed Rotors Driven by Dry or Lubricated Rollers

1985 ◽  
Vol 107 (2) ◽  
pp. 312-319
Author(s):  
S. Wang ◽  
A. Seireg
Keyword(s):  
Coefficient Of Friction ◽  
Dynamic Load ◽  
High Speed ◽  
Contact Forces ◽  
Contact Compliance ◽  
Computer Based ◽  
Load Conditions

This paper presents a computer-based simulation of the vibration and dynamic load conditions in rotors driven by dry or lubricated Hertzian contacts. The effect of clearance coefficient of friction, elastohydrodynamic film, number of drive rollers, and contact compliance on the rotor movement and the contact forces is investigated.

Modeling of Tread Block Contact Mechanics Using Linear Viscoelastic Theory3

2008 ◽  
Vol 36 (3) ◽  
pp. 211-226 ◽  
Author(s):  
F. Liu ◽  
M. P. F. Sutcliffe ◽  
W. R. Graham
Keyword(s):  
High Speed ◽  
Slip Rate ◽  
Material Model ◽  
Contact Forces ◽  
Block Modeling ◽  
Rate Dependent ◽  
Linear Viscoelastic Material ◽  
Linear Viscoelastic ◽  
The Impact ◽  
Good Agreement

Abstract In an effort to understand the dynamic hub forces on road vehicles, an advanced free-rolling tire-model is being developed in which the tread blocks and tire belt are modeled separately. This paper presents the interim results for the tread block modeling. The finite element code ABAQUS/Explicit is used to predict the contact forces on the tread blocks based on a linear viscoelastic material model. Special attention is paid to investigating the forces on the tread blocks during the impact and release motions. A pressure and slip-rate-dependent frictional law is applied in the analysis. A simplified numerical model is also proposed where the tread blocks are discretized into linear viscoelastic spring elements. The results from both models are validated via experiments in a high-speed rolling test rig and found to be in good agreement.

A Nonlinear Rail Vehicle Dynamics Computer Program SAMS/Rail: Part 1—Theory and Formulations

2009 ◽  
Author(s):  
Khaled E. Zaazaa ◽  
Brian Whitten ◽  
Brian Marquis ◽  
Erik Curtis ◽  
Magdy El-Sibaie ◽  
...  
Keyword(s):  
High Speed ◽  
Dynamic Performance ◽  
Three Dimensional ◽  
Contact Element ◽  
Contact Forces ◽  
Simulation Code ◽  
Vehicle Performance ◽  
Normal Contact ◽  
Advantages And Disadvantages ◽  
High Speed Trains

Accurate prediction of railroad vehicle performance requires detailed formulations of wheel-rail contact models. In the past, most dynamic simulation tools used an offline wheel-rail contact element based on look-up tables that are used by the main simulation solver. Nowadays, the use of an online nonlinear three-dimensional wheel-rail contact element is necessary in order to accurately predict the dynamic performance of high speed trains. Recently, the Federal Railroad Administration, Office of Research and Development has sponsored a project to develop a general multibody simulation code that uses an online nonlinear three-dimensional wheel-rail contact element to predict the contact forces between wheel and rail. In this paper, several nonlinear wheel-rail contact formulations are presented, each using the online three-dimensional approach. The methods presented are divided into two contact approaches. In the first Constraint Approach, the wheel is assumed to remain in contact with the rail. In this approach, the normal contact forces are determined by using the technique of Lagrange multipliers. In the second Elastic Approach, wheel/rail separation and penetration are allowed, and the normal contact forces are determined by using Hertz’s Theory. The advantages and disadvantages of each method are presented in this paper. In addition, this paper discusses future developments and improvements for the multibody system code. Some of these improvements are currently being implemented by the University of Illinois at Chicago (UIC). In the accompanying “Part 2” and “Part 3” to this paper, numerical examples are presented in order to demonstrate the results obtained from this research.

scholarly journals Cutting Force Prediction Models by FEA and RSM When Machining X56 Steel with Single Diamond Grit

Micromachines ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 326
Author(s):  
Lan Zhang ◽  
Xianbin Sha ◽  
Ming Liu ◽  
Liquan Wang ◽  
Yongyin Pang
Keyword(s):  
Cutting Force ◽  
Coefficient Of Friction ◽  
High Speed ◽  
Prediction Models ◽  
Pipeline Steel ◽  
Cutting Speed ◽  
Depth Of Cut ◽  
Cutting Force Prediction ◽  
Force Prediction ◽  
Diamond Wire Saw

In the field of underwater emergency maintenance, submarine pipeline cutting is generally performed by a diamond wire saw. The process, in essence, involves diamond grits distributed on the surface of the beads cutting X56 pipeline steel bit by bit at high speed. To find the effect of the different parameters (cutting speed, coefficient of friction and depth of cut) on cutting force, the finite element (FEA) method and response surface method (RSM) were adopted to obtain cutting force prediction models. The former was based on 64 simulations; the latter was designed according to DoE (Design of Experiments). Confirmation experiments were executed to validate the regression models. The results indicate that most of the prediction errors were within 10%, which were acceptable in engineering. Based on variance analyses of the RSM models, it could be concluded that the depth of the cut played the most important role in determining the cutting force and coefficient the of friction was less influential. Despite making little direct contribution to the cutting force, the cutting speed is not supposed to be high for reducing the coefficient of friction. The cutting force models are instructive in manufacturing the diamond beads by determining the protrusion height of the diamond grits and the future planning of the cutting parameters.

scholarly journals Client Aware Scalable Cloudlet to Augment Edge Computing with Mobile Cloud Migration Service

2020 ◽  
Vol 14 (12) ◽  
pp. 165
Author(s):  
Uma Nandhini D ◽  
Udhayakumar S ◽  
Latha Tamilselvan ◽  
Silviya Nancy J
Keyword(s):  
Wireless Lan ◽  
High Speed ◽  
Virtual Machines ◽  
Linear Regression Analysis ◽  
Mobile Cloud ◽  
Cloud Data Center ◽  
Cloud Data ◽  
Battery Lifetime ◽  
Network Bandwidth ◽  
Load Conditions

<p class="0abstract">Computing with mobile is still in its infancy due to its limitations of computational power, battery lifetime and storage capacity. These limitations hinder the growth of mobile computing, which in-turn affects the growth of computationally intensive applications developed for the mobile devices. So in-order to help execute complex applications within the mobile device, mobile cloud computing (MCC) emerged as a feasible solution. The job of offloading the task to the cloud data center for storage and execution from the mobile seems to gain popularity, however, issues related to network bandwidth, loss of mobile data connectivity, and connection setup does not augment well to extend the benefits offered by MCC. Cloudlet servers filled this gab by assisting the mobile cloud environment as an edge device, offering compute power to the connected devices with high speed wireless LAN connectivity. Implementation constraints of cloudlet faces severe challenges in-terms of its storage, network sharing, and VM provisioning. Moreover, the number of connected devices of the cloudlet and its load conditions vary drastically leading to unexpected bottleneck, in which case the availability to server becomes an issue. Therefore, a scalable cloudlet, Client Aware Scalable Cloudlet (CASC) is proposed with linear regression analysis, predicting the knowledge of expected load conditions for provisioning new virtual machines and to perform resource migration.</p>

LCL Filter with Active Damping using PI and SSI Regulators in Synchronous Rotating Reference Frame Current Controller for DSTATCOM

2013 ◽  
Vol 14 (4) ◽  
pp. 309-326
Author(s):  
Nagesh Geddada ◽  
Mahesh Kumar Mishra
Keyword(s):  
Steady State ◽  
Dynamic Load ◽  
Distribution System ◽  
Voltage Drop ◽  
Active Damping ◽  
Voltage Source ◽  
Lcl Filter ◽  
Load Compensation ◽  
Current Controller ◽  
Load Conditions

Abstract This article proposes a distribution static compensator (DSTATCOM) with interface LCL (inductor-capacitor-inductor) filter for load compensation in three-phase four-wire distribution system. DSTATCOM, consisting of voltage source inverter (VSI), is connected in parallel to the load and injects currents corresponding to load reactive, harmonic powers. But this injected current consists of unnecessary high-frequency switching ripple generated by VSI. This LCL filter has superior switching ripple attenuation capability compared to L filter. Moreover, this can be achieved with small value of overall LCL filter inductance than L filter. Thus providing high slew rate for output current to track the desired reference current closely, reducing voltage drop across it, as well as cost and size of filter. However, one major concern with LCL filter is its resonating frequency (determined from its L, C, L values), which can create high-resonance oscillating currents and results in improper load compensation. Therefore, in this study, proper design of LCL filter with high switching ripple attenuation and a current controller with proportional integral (PI) plus harmonic compensation (HC) regulators along with active damping feature of LCL filter in synchronous rotating reference (dq0) frame are presented. HC regulator minimizes the steady-state error in the non-sinusoidal filter currents (fundamental and harmonic) which are tracked by the VSI. Active damping feature (obtained by capacitor current feedback control of LCL filter) is used to overcome resonance oscillations and provides proper control, operation of DSTATCOM under steady-state and dynamic load conditions. Stability studies for designed LCL filter and current controller using Bode and root locus plots are also performed and presented. Extensive simulation study, to understand the compensation performance of LCL filter DSTATCOM with two types of current controllers (PI and PI plus HC) under steady-state and dynamic load conditions, is carried out in PSCAD simulator and the corresponding results along with THDs of various parameters are presented.

Analysis on Vehicle-Bridge Coupled Vibration of a Rigid-Frame Arch Bridge Based on Measured Road Roughness

2011 ◽  
Vol 255-260 ◽  
pp. 1775-1780
Author(s):  
Wan Shui Han ◽  
Su Jing Yuan ◽  
Bing Wang
Keyword(s):  
High Speed ◽  
Contact Forces ◽  
Dynamic Responses ◽  
Coupled Vibration ◽  
Arch Bridge ◽  
Rigid Frame ◽  
Road Roughness ◽  
Left And Right ◽  
Spectrum Characteristics ◽  
Bridge System

Firstly, synchronous field measurements were carried out for the road roughness of the left and right wheels to obtain the roughness profile using a high speed laser roadway testing vehicle. Secondly, programming idea of multi-girder vehicle-bridge coupled vibration analysis module was presented briefly. Finally, a three-axle heavy truck crossing a rigid-frame arch bridge was taken as an example, detailed comparing and analyzing was carried out for the influence on the dynamic responses and spectrum characteristics of the vehicle-bridge system from three excitation cases which include using measured road roughness corresponding respectively to left and right wheels, using measured road roughness of left wheels and right wheels simultaneously. The analysis shows that when the differences in road roughness between left and right wheels are significant, the responses computed with inconsistent excitation is smaller than that with both of the latter two excitation cases, and there are some differences between the vertical contact forces of wheels and the spectrum characteristics of the vehicle-bridge system.

Study on the Application of Marine Biodiesel on High Speed Diesel Engines

2011 ◽  
Vol 287-290 ◽  
pp. 1976-1979
Author(s):  
Lin Cai Ma ◽  
Zhi Guo Zhou ◽  
Liang Yao Xia ◽  
Da Xue Liu ◽  
Xiao Li Yu
Keyword(s):  
Diesel Engine ◽  
High Speed ◽  
Consumption Rate ◽  
Effective Power ◽  
Engine Load ◽  
Bench Tests ◽  
Fuel Consumption Rate ◽  
High Speed Diesel ◽  
Hc Emissions ◽  
Load Conditions

A bench tests were carried out on an YC6J190 diesel engine fueled with B20 marine biodiesel. The results showed that the engine’s effective power decreased by 1.8%, the fuel consumption rate increased by 0.07%, HC emissions decreased by 19.17% and the soot decreased by 25% as average under full engine load conditions. HC decreased by 23.4% and the soot decreased by 23% as average under part engine load conditions. The soot emissions decreased by 28.8% as average under the free acceleration conditions.

Railway Truck Response to Random Rail Irregularities

1975 ◽  
Vol 97 (3) ◽  
pp. 957-964 ◽  
Author(s):  
Neil K. Cooperrider
Keyword(s):  
High Speed ◽  
Degrees Of Freedom ◽  
Equations Of Motion ◽  
Tangential Force ◽  
Contact Forces ◽  
Guidance Force ◽  
Power Spectral ◽  
Power Spectral Densities ◽  
Rail Irregularities ◽  
Frequency Domain Techniques

This paper discusses the random response of a seven degree of freedom, passenger truck model to lateral rail irregularities. Power spectral densities and root mean square levels of component displacements and contact forces are reported. The truck model used in the study allows lateral and yaw degrees of freedom for each wheelset, and lateral, yaw and roll freedoms for the truck frame. Linear creep relations are utilized for the rail-wheel contact forces. The lateral rail irregularities enter the analysis through the creep expressions. The results described in the paper were obtained using frequency domain techniques to solve the equations of motion. The reported results demonstrate that the guidance force needed when traveling over irregular rail at high speed utilizes a significant portion of the total available tangential force between wheel and rail.

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