Experimental Investigation on the Modal Characteristics of Rolling Thick Disk

2012 ◽  
Author(s):  
S. Bashmal ◽  
R. Bhat ◽  
S. Rakheja
Keyword(s):  
Boundary Conditions ◽  
Travelling Waves ◽  
Three Dimensional ◽  
Thick Disk ◽  
Combined Effect ◽  
Experimental Investigations ◽  
Three Dimensional Model ◽  
Annular Disk ◽  
Modal Characteristics ◽  
Non Linear

Analytical and experimental investigations are carried out to study the combined effect of rotation and support non-uniformity on the modal characteristics of circular thick disks. A three-dimensional model is implemented to study the coupled in-plane and out-of-plane modes of a thick disk and present the variations of the travelling waves with respect to rotating and fixed coordinates. The initial stiffening due to rotation is introduced by developing a non-linear model that permits the coupling between static and dynamic problems. The present formulation is generalized to account for the stiffening effects for disks subject to non-uniform boundary conditions, where the initial displacement cannot be considered as axisymmetric. The general non-linear problem of a rotating annular disk subject to non-uniform boundary conditions is, then, investigated. The laboratory experiments on stationary and rotating circular disks under selected boundary conditions are carried out to demonstrate the validity of the analytical methods in terms of vibration and acoustic emission behaviour. The experimental results examine the combined effect of rotation and point support on the disk. The experimental study confirms the split in natural frequencies of the disk that was observed in the analytical results due to both rotation and support non-uniformity.

In-Plane Vibration Modes of Arbitrarily Thick Disks

1997 ◽  
Author(s):  
Kevin I. Tzou ◽  
Jonathan A. Wickert ◽  
Adnan Akay
Keyword(s):  
Natural Frequencies ◽  
Arbitrary Dimension ◽  
Three Dimensional ◽  
Mode Shapes ◽  
Vibration Modes ◽  
Three Dimensional Model ◽  
Bending Vibration ◽  
Annular Disk ◽  
Out Of Plane ◽  
Plane Bending

Abstract The three-dimensional vibration of an arbitrarily thick annular disk is investigated for two classes of boundary conditions: all surfaces traction-free, and all free except for the clamped inner radius. These two models represent limiting cases of such common engineering components as automotive and aircraft disk brakes, for which existing models focus on out-of-plane bending vibration. For a disk of significant thickness, vibration modes in which motion occurs within the disk’s equilibrium plane can play a substantial role in setting its dynamic response. Laboratory experiments demonstrate that in-plane modes exist at frequencies comparable to those of out-of-plane bending even for thickness-to-diameter ratios as small as 10−1. The equations for three-dimensional motion are discretized through the Ritz technique, yielding natural frequencies and mode shapes for coupled axial, radial, and circumferential deformations. This treatment is applicable to “disks” of arbitrary dimension, and encompasses classical models for plates, bars, cylinders, rings, and shells. The solutions so obtained converge in the limiting cases to the values expected from the classical theories, and to ones that account for shear deformation and rotary inertia. The three-dimensional model demonstrates that for geometries within the technologically-important range, the natural frequencies of certain in- and out-of-plane modes can be close to one another, or even identically repeated.

Investigation of Dynamic Photoelasticity Based on a Three-Dimensional Model

2011 ◽  
Vol 83 ◽  
pp. 261-266
Author(s):  
Bin Li ◽  
Guo Biao Yang ◽  
Fan Ni ◽  
Qi Rong Zhu
Keyword(s):  
Boundary Conditions ◽  
High Speed ◽  
Three Dimensional ◽  
Green Laser ◽  
Structure Design ◽  
Dynamic Photoelasticity ◽  
Three Dimensional Model ◽  
Design And Optimization ◽  
True Value ◽  
Dimensional Models

Dynamic photoelasticity has been widely utilized to investigate the phenomena generated by impact loading. The dynamic parameters of structures, such as propagation of stress wave and stress concentration, are obtained through this method, which provide guidelines for structure design and optimization. In the previous studies, two-dimensional models are wildly used by researchers. In these models, the inaccuracy of the boundary conditions leads to error amplification during the conversion of the tested results into real ones. In this study of dynamic photoelasticity, three-dimensional models are used. An improved digital dynamic photoelastic system is also adopted to calculate elastic wave propagation in the medium, where the diode-pumped solid-state green laser and high-speed CCD are used as light source luminaries and recording system respectively. Based on these models, where the boundary conditions approach to true value, the resulting data are higher in resolution than is possible with other experimental techniques. This method has been adopted and tested successfully by generating better results with less amplification of errors.

A Numerical Investigation of Automobile Environment Through Cooling Period and Condensation

2009 ◽  
Author(s):  
Md. Faisal Kader ◽  
Kang Hyu Goo ◽  
Yong-Du Jun ◽  
Kum-Bae Lee
Keyword(s):  
Fluid Flow ◽  
Initial Period ◽  
Three Dimensional ◽  
Practical Significance ◽  
Scale Model ◽  
Design Parameters ◽  
Experimental Investigations ◽  
Three Dimensional Model ◽  
Cooling Period ◽  
Initial Stage

Understanding the fluid flow and heat transfer characteristics within a vehicle compartment is very important for controlling the effect of major design parameters. Also, adequate visibility through the vehicle windshield over the entire driving period is of paramount practical significance. The numerical solution was done by an operation friendly, fast and accurate CFD code — SC/Tetra with a full scale model of a SM3 car and turbulence was modeled by the standard k-ε equation. Numerical analysis of the three-dimensional model predicts a detailed description of fluid flow and temperature distribution in the passenger compartment and on the inside windshield screen. During the cooling period, the lowest temperature is observed in the lower part of the windshield and in the vicinity of the defroster griller. It was found that the temperature dropped down to a comfortable range almost linearly at the initial stage. The initial period to achieve this comfortable range is dependent on the inlet velocity. Experimental investigations are performed to determine the localized thermal comfort and further validation of the numerical results.

A three-dimensional model of Hamilton Harbour incorporating spatial distribution of transient surface drag

1978 ◽  
Vol 5 (4) ◽  
pp. 479-488 ◽  
Author(s):  
William James ◽  
Basem Eid
Keyword(s):  
Boundary Conditions ◽  
Transport Model ◽  
Three Dimensional ◽  
Layered System ◽  
Surface Boundary ◽  
Hydrodynamic Equations ◽  
Three Dimensional Model ◽  
Surface Drag ◽  
Hamilton Harbour ◽  
Surface Boundary Conditions

This paper discusses the formulation of surface boundary conditions for a three-dimensional transport model for shallow lakes, specifically for Hamilton Harbour. The same hydrodynamic equations that describe the circulation of the ocean and the Great Lakes were used in this study. However, the boundary conditions (bed topography, shoreline configuration, and surface and bottom shear stress fields) have bigger effects on circulation in shallow enclosed lakes.In this study the flow is assumed to be incompressible and in hydrostatic equilibrium. A layered system is used in which the lake is considered to consist of a number of unequal layers in the vertical. The hydrodynamic equations are integrated vertically over each layer, and both vertical and horizontal eddy viscosities are introduced.The over-water wind stress is determined using the logarithmic wind velocity distribution and Von Karman's integral equation for turbulent flow over a rough movable surface of variable roughness, in conjunction with equations for wind–wave generation. Thus the wind drag coefficient is determined as a function of wind and wave characteristics, and is time- and space-dependent.

Simulation Research on Micro-Cavity Flow Field Characteristics of Liquid Floating Rotor Gyro

2013 ◽  
Vol 562-565 ◽  
pp. 490-495 ◽  
Author(s):  
Yu Peng Shi ◽  
Fei Tang ◽  
Xiao Hao Wang
Keyword(s):  
Flow Field ◽  
Boundary Conditions ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Cavity Flow ◽  
Three Dimensional Model ◽  
Simulation Research ◽  
Resistance Torque ◽  
Flow Field Characteristics ◽  
Micro Cavity

The liquid floating rotor gyro is a gyroscope using electrostatic or electromagnetic forces to levitate rotor, and filling rotor-stator cavities with liquid in order to improve stability of motion. Under influence of the relative surface roughness, rotor velocity, dimension of flow field and fluid nature, flow characteristics of cavity flow field vary under different boundary conditions and geometrical conditions. This paper adopts three-dimensional model and periodic boundary conditions to conduct numerical modeling on cavity flow field. Its results show that, with velocity rising, distribution of flow field speed and pressure manifests partial fluctuations in turbulent-flow-intensive area; resistance torque amid rotor rotation is nonlinearly correlated with velocity, whose rules can be obtained through high-order curve fitting.

In-Plane Vibration Modes of Arbitrarily Thick Disks

1998 ◽  
Vol 120 (2) ◽  
pp. 384-391 ◽  
Author(s):  
K. I. Tzou ◽  
J. A. Wickert ◽  
A. Akay
Keyword(s):  
Natural Frequencies ◽  
Arbitrary Dimension ◽  
Three Dimensional ◽  
Mode Shapes ◽  
Vibration Modes ◽  
Three Dimensional Model ◽  
Bending Vibration ◽  
Annular Disk ◽  
Out Of Plane ◽  
Plane Bending

The three-dimensional vibration of an arbitrarily thick annular disk is investigated for two classes of boundary conditions: all surfaces traction-free, and all free except for the clamped inner radius. These two models represent limiting cases of such common engineering components as automotive and aircraft disk brakes, for which existing models focus on out-of-plane bending vibration. For a disk of significant thickness, vibration modes in which motion occurs within the disk’s equilibrium plane can play a substantial role in-setting its dynamic response. Laboratory experiments demonstrate that in-plane modes exist at frequencies comparable to those of out-of-plane bending even for thickness-to-diameter ratios as small as 10−1. The equations for three-dimensional motion are discretized through the Ritz technique, yielding natural frequencies and mode shapes for coupled axial, radial, and circumferential deformations. This treatment is applicable to “disks” of arbitrary dimension, and encompasses classical models for plates, bars, cylinders, rings, and shells. The solutions so obtained converge in the limiting cases to the values expected from the classical theories, and to ones that account for shear deformation and rotary inertia. The three-dimensional model demonstrates that for geometries within the technologically-important range, the natural frequencies of certain in- and out-of-plane modes can be close to one another, or even identically repeated.

scholarly journals Investigation of the use of silicone pads to reduce the effects on the human face of classical face masks used to prevent from COVID-19 and other infections

2021 ◽  
pp. 095440892110195
Author(s):  
Kadir Gok
Keyword(s):  
Chronic Disease ◽  
Boundary Conditions ◽  
Virus Vaccine ◽  
Three Dimensional ◽  
Face Mask ◽  
Human Face ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Alternative Method ◽  
Computer Aided

Viruses spreads very quickly and has a fatal risk in people with chronic disease. As the virus vaccine and medications to be used for treatment are not fully developed, alternative ways to protect it from the virus are being investigated. In this study, the effects of a classical face mask on human face were investigated and computer-aided analyses were performed. Three-dimensional model of the classical face mask was performed with the SolidWorks software. The analyses were performed using AnsysWorkbench Static Structural module. The load, boundary conditions and material were defined in the AnsysWorkbench. As a result of the analyses, it has been determined that classical masks influence human face. The classical masks have a negative effective in terms of irritation on the human face. The occurred stresses cause irritation on one's skin. The use of silicone pads has been shown to reduce these effects. It was proved by this study that silicon pads can be used as an alternative method to reduce these stresses. In the future, it is planned to conduct studies investigating mask materials that do not irritate the human face.

The Numerical Simulation on the Atomization Process of Fluid Movement in the Jet Exhausting Atomization Nozzle

2012 ◽  
Vol 182-183 ◽  
pp. 1408-1412
Author(s):  
Yan Song Zhu
Keyword(s):  
Numerical Simulation ◽  
Liquid Droplet ◽  
Three Dimensional ◽  
Experimental Investigations ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Atomization Process ◽  
Related Factors ◽  
Fluid Movement ◽  
Atomization Nozzle

The atomization process of liquid droplet is an important stage in the fluid movement process in the jet exhausting atomization nozzle. This stage is directly influenced on the diameter and desperation of water droplet. Today two-dimensional model is often used in the most common simulation framework. But the atomization process in nozzle is usually happened in the three-dimensional model, so the results are not quite agreed with the practice. In this paper, a new three-dimensional model was proposed to study the mechanism of the atomization process. After applying the VOF method and turbulent model in CFD software Fluent, a numerical simulation was performed to analyze the mechanism of atomization process and some related factors affecting the atomization. Results indicated that the shapes of atomization were accorded with experimental investigations. According to the results, the necessity of further characteristic parameters on the atomization process was analyzed.

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