scholarly journals Prediction of Room Noise Caused by Vibration of High Power Elevator Traction Machine

2021 ◽  
Vol 8 ◽  
pp. 16-20
Author(s):  
Shinichi Noda ◽  
Yoshitake Kamijo ◽  
Sueyoshi Mizuno ◽  
Makoto Matsushita
Keyword(s):  
Natural Frequency ◽  
High Power ◽  
Wave Motion ◽  
Acoustic Noise ◽  
Frequency Mode ◽  
Design Stage ◽  
Wave Phase ◽  
Phase Interference

Total simulation from vibration of elevator motor to noise at sitting room with anti-vibration measures is confirmed in design stage. This procedure also presents decrease of acoustic noise in sitting room. In this simulation, FEM calculates wave motion, such as wave phase, interference, diffraction and natural frequency mode of sitting room wall. These procedures yield the ration between vibration of elevator motor and acoustic noise in sitting-room.

Similitudes for vibration characteristic of composite laminated plates

2021 ◽  
pp. 107754632110377
Author(s):  
Fengxia He ◽  
Zhong Luo ◽  
Lei Li ◽  
Xiaoxia Zhang
Keyword(s):  
Natural Frequency ◽  
Prediction Accuracy ◽  
Laminated Plates ◽  
Frequency Mode ◽  
Mode Shapes ◽  
Vibration Characteristic ◽  
Modal Assurance Criterion ◽  
Full Size ◽  
Composite Laminated Plates ◽  
Scaled Models

Similitude laws can be used to extrapolate the vibration characteristic of a small, inexpensive, and easily tested model into structural behavior for the full-size prototype. In this article, a systematic similitude approach is proposed to predict the natural frequency, mode shape, and vibration response of composite laminated plates. The emphasis of this article is to predict the vibration characteristic of composite laminated plates in an effective and convenient way. Sensitivity analysis (SA) is introduced to improve the prediction accuracy of natural frequency. For distortion similarity, the prediction accuracy is improved close to 5%. Modal assurance criterion (MAC) measures the consistency of mode shapes of the full-size prototype and scaled models. The influence of stacking sequence on mode consistency is investigated. Similitude based on virtual mode and statistical energy (SVMSE) is proposed to extrapolate the transient response of the prototype to simulate the shock environment, such as satellite–rocket separation, etc. In conclusion, the prediction accuracy of natural frequency, mode consistency, and response coincidence are considered comprehensively to extrapolate the vibration characteristic of the full-size laminated plates.

Springing Responses Analysis and Segmented Model Testing on a 550,000 DWT Ore Carrier

2016 ◽  
Author(s):  
Hui Li ◽  
Di Wang ◽  
Cheng Ming Zhou ◽  
Kaihong Zhang ◽  
Huilong Ren
Keyword(s):  
Natural Frequency ◽  
Design Stage ◽  
Resonant Vibration ◽  
Bending Moments ◽  
Wave Loads ◽  
Regular Waves ◽  
Segmented Model ◽  
Ship Model ◽  
Hull Structure ◽  
Stiffness Distribution

For ultra large ore carriers, springing response should be analyzed in the design stage since springing is the steady-state resonant vibration and has an important effect on the fatigue strength of hull structure. The springing response of a 550,000 DWT ultra large ore carrier has been studied by using experimental and numerical methods. A flexible ship model composed of nine segments was used in the experiment. The model segments were connected by a backbone with varying section, which can satisfy the request of natural frequency and stiffness distribution. The experiments in regular waves were performed and the motions and wave loads of the ship were measured. The experimental results showed that springing could be excited when the wave encounter frequency coincides with half or one-third the flexural natural frequency of the ship. In this paper, the analysis of the hydroelastic responses of the ultra large ore carrier was also carried out using a 3-D hydroelastic method. Comparisons between experimental and numerical results showed that the 3-D hydroelastic method could predict the motions and the vertical bending moments quite well. Based on this numerical method, the fatigue damage was estimated and the contribution of springing was analyzed.

The Underwater Effects of High Power, High Frequency Acoustic Noise on MEMS Gyroscopes

2011 ◽  
Author(s):  
William N. Yunker ◽  
Pregassen Soobramaney ◽  
Meagan Black ◽  
Robert N. Dean ◽  
George T. Flowers ◽  
...  
Keyword(s):  
High Power ◽  
High Frequency ◽  
Proof Mass ◽  
Acoustic Noise ◽  
Angular Rate ◽  
Autonomous Underwater Vehicles ◽  
Mechanical Shock ◽  
Negative Effects ◽  
Mems Gyroscopes ◽  
New Applications

Unlike their macroscale counterparts, MEMS gyroscopes use a vibrating proof mass rather than a rotational mass to sense changes in angular rate. They are also smaller and less expensive than traditional gyroscopes. For this reason, MEMS gyroscopes are being used in many new applications, some of which include operation in harsh environments. There has been much research on the negative effects of the performance of MEMS gyroscopes in environments that experience mechanical shock, high frequency vibration, and high frequency acoustic noise in air. However, MEMS gyroscopes are beginning to be used in underwater applications such as autonomous underwater vehicles, digital compasses, and torpedo guidance systems. The results of this experiment demonstrate that MEMS gyroscopes submerged in water are susceptible to high power, high frequency acoustic noise at and near the resonant frequency of the proof mass. These effects are demonstrated using the ADXRS300 MEMS gyroscope.

Natural Frequency Region – Fluid-Structural-Interaction approach for dynamic impact predictions and experimental verification of rubber–metal bonded systems with fluid

2018 ◽  
Vol 233 (2) ◽  
pp. 211-219 ◽  
Author(s):  
Robert K Luo ◽  
Ping Lou ◽  
Weidong Wang ◽  
Naizheng Guo
Keyword(s):  
Natural Frequency ◽  
Experimental Verification ◽  
Time Frame ◽  
Frequency Region ◽  
Design Stage ◽  
Dynamic Impact ◽  
Structural Interaction ◽  
Central Processing ◽  
Interaction Approach ◽  
Impact Predictions

This paper presents an integrated procedure for dynamic impact predictions and an experimental verification of rubber–metal bonded components with fluid to be used as a potential application in rail vehicle suspensions. There are three steps involved in the procedure. First, a quasi-static analysis was performed to verify the elastic properties of the rubber material using hyperelastic models. Second, a dynamic impact evaluation on selected hydro-mounts without fluid was conducted using the Natural Frequency Region (NFR) approach. Finally, a coupled NFR (with Fluid-Structural-Interaction) approach, different from the usual viscoelastic methods, was initiated to predict the dynamic impact responses of these components with the fluid in time domain. All the analyses have been validated with experimental data. The first two stages have been briefly described and the third stage is detailed in this paper. It should be noted that a powerful computer with multi-central processing units is essential to obtain a reasonable result within an acceptable time frame. It took approximately 40 h wall-clock time to complete the analysis using a workstation with 10 central processing units. It has been suggested that the natural frequency region–fluid–structure interaction methodology is reliable and could be used at the design stage and for engineering applications.

Enhanced Miniature Loop Heat Pipe Cooling System for High Power Density Electronics

2012 ◽  
Vol 4 (2) ◽  
Author(s):  
J. H. Choi ◽  
B. H. Sung ◽  
J. H. Yoo ◽  
C. J. Kim ◽  
D.-A. Borca-Tasciuc
Keyword(s):  
Heat Transfer ◽  
Thermal Resistance ◽  
Power Density ◽  
Thermal Performance ◽  
High Power ◽  
Design Stage ◽  
Working Fluid ◽  
High Power Density ◽  
Graphic Processing Units ◽  
Maximum Heat

The implementation of high power density, multicore central and graphic processing units (CPUs and GPUs) coupled with higher clock rates of the high-end computing hardware requires enhanced cooling technologies able to attend high heat fluxes while meeting strict design constrains associated with system volume and weight. Miniature loop heat pipes (mLHP) emerge as one of the technologies best suited to meet all these demands. Nonetheless, operational problems, such as instable behavior during startup on evaporator side, have stunted the advent of commercialization. This paper investigates experimentally two types of mLHP systems designed for workstation CPUs employing disk shaped and rectangular evaporators, respectively. Since there is a strong demand for miniaturization in commercial applications, emphasis was also placed on physical size during the design stage of the new systems. One of the mLHP system investigated here is demonstrated to have an increased thermal performance at a reduced system weight. Specifically, it is shown that the system can reach a maximum heat transfer rate of 170 W with an overall thermal resistance of 0.12 K/W. The corresponding heat flux is 18.9 W/cm2, approximately 30% higher than that of larger size commercial systems. The studies carried out here also suggest that decreasing the thermal resistance between the heat source and the working fluid and maximizing the area for heat transfer are keys for obtaining an enhanced thermal performance.

Liquid sloshing and wave breaking in circular and square-base cylindrical containers

2007 ◽  
Vol 577 ◽  
pp. 467-494 ◽  
Author(s):  
A. ROYON-LEBEAUD ◽  
E. J. HOPFINGER ◽  
A. CARTELLIER
Keyword(s):  
Natural Frequency ◽  
Wave Breaking ◽  
Wave Motion ◽  
Wave Amplitude ◽  
Variable Parameter ◽  
Frequency Offset ◽  
Vortical Flow ◽  
Wave Crest ◽  
Wide Range ◽  
Planar Wave

Near resonance sloshing in containers, filled with a liquid to a given depthh, depends on three parameters, which are the viscous damping, the frequency offset that contains the forcing amplitude and the fluid depth. Experiments have been conducted with low-viscosity liquids mainly in circular cylindrical containers of radiusRsubjected to harmonic horizontal forcing; complementary experiments on wave breaking have been performed in a square-base container. The fluid depth was kept large (h/R> 1) so that it was no longer a variable parameter. The bounds of existence of the different wave regimes, namely planar waves, swirling waves, chaotic sloshing as well as breaking waves, have been determined as a function of forcing frequencies relative to the lowest natural frequency ω1and for a wide range of forcing amplitudes. It is shown that when the forcing frequency ω is slightly larger than the lowest natural frequency ω1, planar wave motion bifurcates to a swirling wave mode at finite wave amplitude, the value of which depends on the offset parameter. The swirl wave amplitude grows exponentially and saturates at a certain value. The swirl has a hard-spring behaviour, is very robust and can generate a vortical flow of the liquid column. Chaotic sloshing and wave breaking occur quasi-periodically: growth of planar wave amplitude at a rate depending on the forcing amplitude, collapse, irregular swirl and again growth of planar wave amplitude. The details and periodicity of the chaotic behaviour and breaking depend on the frequency-offset parameter. Close to the natural frequency, chaotic wave motion is possible without breaking. Planar wave breaking is, in general, associated with spilling caused by the encounter of nearly freely falling lumps of fluid with the upward moving wave crest, in a way demonstrated previously in two-dimensional wave breaking. In three dimensions, the wave crest is destabilized in the crosswise direction so that spilling is not uniform along the wave crest and an irregular swirl is generated following breaking; free fall of fluid lumps occurs over many wave periods. The complementary experiments, performed in a square-base container of base dimensionL, show four different wave patterns of wavelengthsLandL/2 crosswise to the primary wave. This cross-wave instability is interpreted in terms of parametric instability.

Influence of equipment rigidity on the natural bending frequency of the EMU train car body

2018 ◽  
Vol 77 (4) ◽  
pp. 251-255
Author(s):  
R. V. Guchinsky
Keyword(s):  
Natural Frequency ◽  
Specific Weight ◽  
The Body ◽  
Design Stage ◽  
Static Characteristics ◽  
Bending Vibrations ◽  
Car Body ◽  
Design Documentation ◽  
Normalized Parameters ◽  
Concentrated Masses

The first frequency of the own bending vibrations of the car body of the EMU train is one of the main normalized parameters associated with smooth running. Estimation of this parameter at the design stage allows to accelerate the process of development of design documentation and to reduce further number of tests. Rigidity of the undercarriage and roof equipment of the EMU train cars contributes to the overall rigidity of the body. When simulating the equipment with concentrated masses at the attachment points, underestimating the rigidity of the body results in underestimated values of the first natural frequency of bending vibrations of the body. It is shown that modeling the equipment with a rigid area with subordinate nodes at the attachment points makes it possible to simplify the process of constructing the model and adequately take into account the rigidity of the equipment not only in determining the static characteristics of body deflections, but also in calculating the dynamic characteristic and the first natural frequency. Using subordinate nodes of a rigid area on the surfaces of the fixing holes leads to a reassessment of the natural frequency. Value of the first natural frequency of the body oscillations is linearly dependent on the specific weight of the undercarriage equipment. When designing the bodies of EMU train cars (especially motor cars), in order to increase the frequency value, the equipment boxes should be located, taking into account the compatibility of the deformations of the box frames and the loadbearing structure of the body. Massive boxes for small equipment should be placed as close to the bolster beams as possible. If it is necessary to place largesize boxes under the car equipment, one should consider variants of its location in the central part of the body to include the box frames in the bend of the transverse beams of the frame.

Frequency Domain Structural Optimization of a Flexible Manipulator Incorporating a PD Controller in the Design Stage

1999 ◽  
Author(s):  
Yong Hoon Chang ◽  
Ali Seireg
Keyword(s):  
Structural Optimization ◽  
Natural Frequency ◽  
Dynamic Performance ◽  
Integrated Design ◽  
Flexible Manipulator ◽  
Design Stage ◽  
Pd Controller ◽  
Design Strategies ◽  
Flexible Mode ◽  
Modal Mass

Abstract This study investigates the potential advantages of integrated design strategies for flexible manipulators that utilize a controller in the process of optimizing the structural design. Clamped free and clamped mass beam models are considered in the investigation for the structural optimization with respect to natural frequencies and mass. A PD controller is utilized in the design process with several objective functions that incorporate weighted combinations of the mass of the structure, modal mass, modal stiffness, and the natural frequency of the rigid mode and the dominant natural frequency of the flexible mode. The results show that the objective function, which minimizes the mass and the product of the modal mass and modal stiffness of the rigid mode and maximize the natural frequency of the flexible mode with appropriate weighting factors, gave the best dynamic performance. Although a two link tubular planar manipulator with a PD controller and assumed beam models for the links is considered in the optimization based on modal parameters, the reported approach can be extended to time domain optimization of multi-link spacial robots with complex structures designed to perform particular tasks.

A New Kind of Energy Transfer From the High-Frequency to Low-Frequency Mode in a Composite Laminated Plate

2010 ◽  
Author(s):  
Wei Zhang ◽  
Xiang-Ying Guo ◽  
Qian Wang ◽  
Cui-Cui Liu ◽  
Yun-cheng He
Keyword(s):  
Numerical Simulation ◽  
Natural Frequency ◽  
Thin Plate ◽  
High Frequency ◽  
Low Frequency ◽  
Frequency Mode ◽  
Rectangular Thin Plate ◽  
Chaotic Motions ◽  
Simply Supported ◽  
Low Frequency Mode

This paper focuses on the analysis on a new kind of nonlinear resonant motion with the low-frequency large-amplitude, which can be induced by the high-frequency small-amplitude mode through the mechanism of modulation of amplitude and phase. The system investigated is a simply supported symmetric cross-ply composite laminated rectangular thin plate subjected to parametric excitations. Experimental research has been carried out for the first time. The test plate was excited near the first natural frequency with parametric forces and the above mentioned high-to-low frequency mode has been observed, whose frequency is extremely lower than the first natural frequency. Theoretical job goes to analysis the above phenomenon accordingly. Based on the Reddy’s third-order shear deformation plate theory and the von Karman type equation, the nonlinear governing equations of the simply supported symmetric cross-ply composite laminated rectangular thin plate subjected to parametric excitations are formulated. The Galerkin method is utilized to discretize the governing partial differential equations into a two-degree-of-freedom nonlinear system. Numerical simulation is conducted to investigate this non-autonomous system subsequently. The results of numerical simulation demonstrate that there is a qualitative agreement between the experimental observation and the theoretical result. Besides, the multi-pulse chaotic motions are also reported in numerical simulations.

An Experimental Investigation of the Miniature Loop Heat Pipe Cooling Systems for High Power Density Computer Chips

2011 ◽  
Author(s):  
Jeehoon Choi ◽  
Junghyun Yoo ◽  
Byungho Sung ◽  
Chulju Kim ◽  
Diana-Andra Borca-Tasciuc
Keyword(s):  
Heat Flux ◽  
Heat Pipe ◽  
Power Density ◽  
High Power ◽  
Design Stage ◽  
Loop Heat Pipe ◽  
High Power Density ◽  
Graphic Processing Units ◽  
Maximum Heat ◽  
Maximum Heat Transfer

The implementation of high power density, multi-core central and graphic processing units (CPUs and GPUs) coupled with higher clock rates of the high-end computing hardware requires enhanced cooling technologies able to attend high heat fluxes while meeting strict design constrains associated with system volume and weight. Miniature loop heat pipe (mLHP) systems emerge as one of the technologies best suited to meet all these demands. This paper investigates experimentally a mLHP system designed for workstation CPUs. The system incorporates a two-phase flow loop with capillary driving force. Since there is a strong demand for miniaturization in commercial applications, emphasize was also placed on physical size during the design stage of the new system. Hence system weight is reduced to around 450g, significantly smaller than that of commercial coolers consisting of copper heat sinks that weight around 782g. Experimental characterization shows that the system can reach a maximum heat transfer rate of 170W with an overall thermal resistance of 0.12 K/W. The heat flux is 18.9 W/cm2, approximately 30% higher than that of larger size commercial systems. To further miniaturize the evaporator module while maintaining the same heat flux, a new structure for the porous evaporator is proposed, which consist of a porous bi-layer, with nanopores at the top surface. The role of the nanoporous layer is to provide a larger surface area for phase-change, enhancing the evaporation rate.

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