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Articles 1 - 12 of 12
Full-Text Articles in Engineering
Application Of Vibration Measurements And Finite Element Model Updating For Structural Health Monitoring Of Ballasted Railtrack Sleepers With Voids And Pockets, Sakdirat Kaewunruen, Alexander Remennikov
Application Of Vibration Measurements And Finite Element Model Updating For Structural Health Monitoring Of Ballasted Railtrack Sleepers With Voids And Pockets, Sakdirat Kaewunruen, Alexander Remennikov
Alex Remennikov
Although vibration measurements are very useful and common in practice nowadays in many applications related to mechanical, civil, and aerospace engineering, the utilisation in railtrack infrastructure and facilities is not widely established. This chapter deals with the application of vibration measurements and finite element model updating to the assessment of ballasted railtrack sleepers, in particular with a void and pocket condition. It describes the concept of vibration measurements and the understanding into the dynamic behaviour of ballasted railtrack sleepers. It discusses briefly on the development of finite element model of in-situ sleeper and its updating. Then, the application to structural …
Trends In Vibration-Based Structural Health Monitoring Of Railway Sleepers, Sakdirat Kaewunruen, Alexander Remennikov
Trends In Vibration-Based Structural Health Monitoring Of Railway Sleepers, Sakdirat Kaewunruen, Alexander Remennikov
Alex Remennikov
Today vibration-based structural health monitoring (SHM) has been widely used in many applications, i.e. mechanical, civil, or aerospace engineering. Over last decades, SHM has been investigated for uses in those applications as an alternative tool to the costly visual inspections. Most of the SMH applications make effective use of experimental modal analysis and finite element model updating whereas this approach consumes reasonable cost for instrumentation and device (generally only a few accelerometers installed on the structure). In railway communities however, SHM technologies have not been widely adopted as the rail track engineers lack efficient tools and instrumentation to process the …
Real Time Prediction Of Vehicle Mirror Vibration, Antoine Larchez, Fazel Naghdy
Real Time Prediction Of Vehicle Mirror Vibration, Antoine Larchez, Fazel Naghdy
Professor Fazel Naghdy
The external and internal mirrors used particularly in high mass recreational and commercial vehicles are prone to vibrations. Under certain conditions, this leads to blurring of the reflected images above the tolerable levels for the human vision. While such vibrations are quite disturbing, they can compromise the driver's safety on the road. A hybrid adaptive predictive method is under development to dynamically compensate for the mirror vibrations under different driving conditions. The first stage of the work which consists of the development of an Auto-Regressive-Integrated-Moving-Average (ARIMA) model is reported. The progress made and the results obtained so far are provided.
Raman Spectroscopic Study Of Solid Solution Spinel Oxides, Brian D. Hosterman
Raman Spectroscopic Study Of Solid Solution Spinel Oxides, Brian D. Hosterman
UNLV Theses, Dissertations, Professional Papers, and Capstones
Solid solution spinel oxides of composition MgxNi1−xCr2O4, NiFexCr2−xO4, and FexCr3−xO4 were synthesized and characterized using x-ray diffraction and Raman spectroscopy. Frequencies of the Raman-active modes are tracked as the metal cations within the spinel lattice are exchanged. This gives information about the dependence of the lattice vibrations on the tetrahedral and octahedral cations. The highest-frequency Raman-active mode, A1g, is unaffected by substitution of the divalent tetrahedral cation, whereas the lower frequency vibrations are more strongly affected by substitution of the tetrahedral cation. The change in wavenumber of many phonons is nonlinear upon cation exchange. All detected modes of MgxNi1−xCr2O4 and …
Experimental Characterization Of Baffle Plate Influence On Turbulent And Cavitation Induced Vibrations In Pipe Flow, Gavin J. Holt
Experimental Characterization Of Baffle Plate Influence On Turbulent And Cavitation Induced Vibrations In Pipe Flow, Gavin J. Holt
Theses and Dissertations
Turbulent and cavitation induced pipe vibration is a large problem in industry often resulting in pipe failures. This thesis provides an experimental investigation on turbulent flow and cavitation induced pipe vibration caused by sharp edged baffle plates. Due to large pressure losses across a baffle plate, cavitation can result. Cavitation can be destructive to pipe flow in the form of induced pipe wall vibration and cavitation inception. Incipient and critical cavitation numbers are design points that are often used in designing baffle plate type geometries. This investigation presents how these design limits vary with the influencing parameters by exploring a …
Method For Determination Of Complex Moduli Associated With Viscoelastic Material, Russell Scott Garner
Method For Determination Of Complex Moduli Associated With Viscoelastic Material, Russell Scott Garner
Masters Theses
The aerospace industry is utilizing low cost miniature inertial measurement units (IMUs) that employ Micro Electro-Mechanical Systems (MEMS) technology in an effort to reduce size, weight, and cost of systems. A drawback of these MEMS devices is they are sensitive to vibration, shock and acoustic environments, which limits the usefulness of such devices in the severe environments imposed by many aerospace applications. In an effort to reduce the vibration, shock and acoustic environments experienced by these MEMS devices, the desire to develop passive damping treatments to structural components used to mount these devices. The damping treatments can be applied at …
Method Of Tolerance Allocation To Maintain Rotary Balance Of Multi-Component Bodies, Lindsay Louise Rogers
Method Of Tolerance Allocation To Maintain Rotary Balance Of Multi-Component Bodies, Lindsay Louise Rogers
Master's Theses (2009 -)
Vibration of rotating machinery caused by mass imbalance is the most frequent source of unwanted disturbing forces and also the most preventable. In the case of a CT scanner, unwanted vibration in the equipment causes artifacts to the X-ray image, and therefore all measures are taken to eliminate imbalance. The CT scanner is a multi-component rotating body, therefore making it a challenge to account for many discrete components, each with unique variation. This research developed the equations for static and dynamic balance including considerations for inertia. The variation of the components was studied using two models: a sensitivity analysis and …
Vibratory Behavior Of Rolling Element Bearings: A Lagrangian Approach, Phani Krishna Kalapala
Vibratory Behavior Of Rolling Element Bearings: A Lagrangian Approach, Phani Krishna Kalapala
ETD Archive
Vibratory behavior of a rolling element bearing on a horizontal rotor is studied in this work. This Thesis analyzes the dynamics of a typical roller bearing as a result of internal excitations. These internal excitations stem from the geometric deviations of the interacting surfaces from their ideal geometry. Such deviations in turn are the results of either manufacturing limitations or normal wear of the bearing surfaces. Lagrangian approach is implemented to derive the dynamic equations of motion. Matlab is used to solve the equation of motion of governing the vibrations of the system. Parametric studies are conducted to provide results …
Application Of Active Magnetic Force Actuator For Control Of Flexible Rotor System Vibrations, Volodymyr Mykhaylyshyn
Application Of Active Magnetic Force Actuator For Control Of Flexible Rotor System Vibrations, Volodymyr Mykhaylyshyn
ETD Archive
The purpose of this work was to develop and experimentally demonstrate a novel approach to minimize lateral vibrations of flexible rotor. The applied feed forward control approach employed magnetic force actuator to inject a specially designed force to counteract the rotor unbalance force. By specific selection of frequency and phase as functions of the rotor running speed and rotor natural frequency, the proposed simplified injection waveform has been shown to be effective both in reducing the rotor's vibrations and for hardware implementation. A model of the test rig was constructed using the finite element (FE) method and was validated using …
Evaluation Methods For Health Monitoring Of Aerospace Structure Rotary Joints, Sergio Armando Navarro
Evaluation Methods For Health Monitoring Of Aerospace Structure Rotary Joints, Sergio Armando Navarro
Open Access Theses & Dissertations
In September 2007, the excessive vibrations played a significant role in the station operation since one of the rotary joints, which provides the station electrical energy, presented an anomaly. The replacement of its bearing components and re-lubrication were necessary to reduce the problem. To avoid a new anomaly, the inspection of the rotary joints performance continues by using the accelerometers data. This thesis presents three new approaches to monitor the vibrations at the International Space Station based on Root-Mean-Square, kurtosis, and Approximate Entropy (ApEn). MATLAB functions and codes were necessary to implement the three monitoring techniques results from the provided …
Active Vibration Control Of Seismic Excited Structural System Using Lmi-Based Mixed H_2/H_{\Infty} State Feedback Controller, Hakan Yazici, Rahmi̇ Güçlü
Active Vibration Control Of Seismic Excited Structural System Using Lmi-Based Mixed H_2/H_{\Infty} State Feedback Controller, Hakan Yazici, Rahmi̇ Güçlü
Turkish Journal of Electrical Engineering and Computer Sciences
This paper is concerned with the active vibration control of a four-degree-of-freedom structure, which is effected by earthquake. To obtain desired time history and frequency responses for solution of active vibration control problem, Linear Matrix Inequality (LMI) based state-feedback mixed H_2/H_{\infty} controller is designed in this study. The time history of ground motion of the Kobe earthquake in 1995, which is a disturbance input, is applied to modeled structure. At the end of the study, the time history of the storey displacements, velocities and frequency responses of both controlled and uncontrolled cases are presented and results are discussed. Performance of …
Vibrational Analysis Of Soloflex Whole Body Vibration Platform, Zachary Croatt, Josh Robers
Vibrational Analysis Of Soloflex Whole Body Vibration Platform, Zachary Croatt, Josh Robers
The Journal of Undergraduate Research
A Soloflex Whole Body Vibration (WBV) Platform was tested for its frequency and magnitude of vibration at multiple settings on the supplied dial. An accelerometer was used to measure the vibrations on different points mapped across the platform. The motor attached to the board was also tested for its frequency using a high-speed camera. The amplitude measurements found from the accelerometer data was compared to the readings on the supplied control module to “calibrate” the platform for medical testing.