Analysis of High-Speed Rotating Disks With Variable Thickness and Inhomogeneity

1994 ◽  
Vol 61 (1) ◽  
pp. 186-191 ◽  
Author(s):  
Kai-Yuan Yeh ◽  
R. P. S. Han
Keyword(s):  
High Speed ◽  
Elevated Temperatures ◽  
Rotating Disk ◽  
Rotating Disks ◽  
Analytic Expressions ◽  
Inhomogeneous Temperature ◽  
Inhomogeneous Temperature Field ◽  
Thermoelastic Stresses ◽  
Shrink Fit ◽  
Annular Disks

A rotating disk with varying thickness and inhomogeneity, and subjected to a steady, inhomogeneous temperature field is analyzed. To handle the arbitrary profile, the disk is discretized into a series of uniform annular disks possessing constant material properties and then solved by the step-reduction method. Analytic expressions for thermoelastic stresses are given, and based on these results, the formulation is extended to include the calculation of shrink fit, the solving of the inverse problem for equistrength rotating disks, and the computations of plastic stresses and creep at elevated temperatures.

In-Plane Vibration Mode Shapes for Rotating Disks: Exact Solution

2020 ◽  
Author(s):  
Ehsan Sarfaraz ◽  
Hamid R. Hamidzadeh
Keyword(s):  
High Speed ◽  
Angular Speed ◽  
Free Vibrations ◽  
Polar Coordinates ◽  
Mode Shapes ◽  
Rotating Disks ◽  
Stress Theory ◽  
Annular Disks ◽  
Modal Vibration

Abstract An analytical method is developed for the determination of modal vibration characteristics of high speed rotating annular disks. A systematic approach based on established solutions for the linear in-plane free vibrations of the disks which satisfy the displacement and stresses compatibilities is developed. The disk is considered to be a homogeneous, thin and elastic isotropic, and it is rotating at constant angular speed. The developed analytical solution was obtained by implementing the two-dimensional plane stress theory. In this research, fixed-free and free-free boundary conditions for the annular disks are considered, and natural frequencies, as well as mode shapes of the rotating disks, are computed. The mode shapes are represented by eight functions in polar coordinates. The dimensionless natural frequency parameters are depicted for free vibration of the system for a range of dimensionless rotation speed and radius ratios. Also, the results provide several non-dimensional critical speeds.

Optimum Design of Inhomogeneous Rotating Disks for Minimum Creep Induced Radial Displacement

2011 ◽  
Vol 133 (5) ◽  
Author(s):  
Behrooz Farshi ◽  
Jalal Bidabadi
Keyword(s):  
Temperature Gradient ◽  
Thermal Stresses ◽  
Elevated Temperatures ◽  
Thickness Distribution ◽  
Turbine Blades ◽  
Rotating Disk ◽  
Optimization Method ◽  
Rotating Disks ◽  
Power Generators ◽  
Disk Material

Gas turbine disks are subject to mechanical stresses due to centrifugal forces exerted by the blades, as well as thermal stresses due to high temperature gradient. High stresses in the presence of elevated temperatures cause the rotating disk material to undergo considerable creep. This phenomenon is significant particularly in cases of turbine blades for power generators, which run almost continuously. Creep strains, in time, lead to deformations resulting in increase of the disk diameter, causing the clearance between blade tips and the turbine’s outer shell to reduce in time. As the above clearance gap is usually limited, this matter is of concern in the design of such equipment for long life. In this investigation, an optimization method is formulated, which is capable of proportioning the thickness distribution of inhomogeneous rotating disks under temperature gradient, so that their long term radii increase due to creep would be minimum. An example is given, which shows the viability of the method.

Centrifugal and Thermal Stresses in Rotating Disks

1948 ◽  
Vol 15 (4) ◽  
pp. 322-326
Author(s):  
W. R. Leopold
Keyword(s):  
Temperature Gradient ◽  
Thermal Stresses ◽  
Elevated Temperatures ◽  
Rotating Disk ◽  
Heat Transfer Analysis ◽  
Rotating Disks ◽  
Radial Temperature Gradient ◽  
Radial Temperature ◽  
Disk Material ◽  
Method Of Solution

Abstract A general semigraphical method, a combination and continuation of the solutions indicated by Stodola and Timoshenko, was found by which the thermal and centrifugal stresses in a rotating disk of any arbitrary profile could be determined. This relatively simple and rapid method of solution requires for its application elementary arithmetic involved in the completion of a tabular form sheet, a temperature gradient along the radius of the disk, which may be approximated by an exponential function of the radius, and easily accommodates changes in the physical properties of the disk material at elevated temperatures. A disk profile and expected radial temperature gradient, as determined from heat-transfer analysis, were taken as an example, and the complete disk stresses calculated directly to demonstrate the use of the method.

RED CUT COBALT

Alloy Digest ◽  
1980 ◽  
Vol 29 (8) ◽  
Keyword(s):  
Fracture Toughness ◽  
Cast Iron ◽  
High Speed ◽  
Elevated Temperatures ◽  
High Speed Steel ◽  
Heat Treating ◽  
High Speeds ◽  
Red Hardness ◽  
Nonferrous Alloys ◽  
Cutting Point

Abstract RED CUT COBALT steel is made by adding 5% cobalt to the conventional 18% tungsten -4% chromium-1% vanadium high-speed steel. Cobalt increases hot or red hardness and thus enables the tool to maintain a higher hardness at elevated temperatures. This steel is best adapted for hogging cuts or where the temperature of the cutting point of the tool in increased greatly. It is well adapted for tools to be used for reaming cast-iron engine cylinders, turning alloy steel or cast iron and cutting nonferrous alloys at high speeds. This datasheet provides information on composition, physical properties, and hardness as well as fracture toughness. It also includes information on forming, heat treating, and machining. Filing Code: TS-367. Producer or source: Teledyne Vasco.

Vibration Measurement and Monitoring of a Rotating Disk Using Contactless Laser Excitation

2013 ◽  
Author(s):  
Itsuro Kajiwara ◽  
Naoki Hosoya
Keyword(s):  
Laser Doppler Vibrometer ◽  
Rotating Disk ◽  
Disk Drive ◽  
Vibration Characteristics ◽  
Vibration Measurement ◽  
Testing System ◽  
Rotating Disks ◽  
Vibration Testing ◽  
Structural Surface ◽  
Theoretical Analyses

This paper proposes a contactless vibration testing system for rotating disks based on an impulse response excited by a laser ablation. High power YAG pulse laser is used in this system for producing an ideal impulse force on structural surface without contact. The contactless vibration testing system is composed of a YAG laser, laser Doppler vibrometer and spectrum analyzer. This system makes it possible to measure vibration characteristics of structures under operation, such as vibration measurement of a rotating disk. The effectiveness of this system is confirmed by experimental and theoretical analyses. In this paper, a platter of hard disk drive is employed as an experimental object. Vibration characteristics of a rotating and non-rotating platter are measured and compared with the results of theoretical analysis.

Nonlinear Resonant Motion of Traveling Waves in Rotating Disks

2000 ◽  
Author(s):  
Albert C. J. Luo ◽  
Chin An Tan
Keyword(s):  
Traveling Waves ◽  
Rotation Speed ◽  
Rotating Disk ◽  
Disk Drive ◽  
Computer Memory ◽  
Rotating Disks ◽  
Resonant Wave ◽  
Linear And Nonlinear ◽  
Resonant Spectrum ◽  
Disk Drive Industry

Abstract The resonant conditions for traveling waves in rotating disks are derived. The nonlinear resonant spectrum of a rotating disk is computed from the resonant conditions. Such a resonant spectrum is useful for the disk drive industry to determine the range of operational rotation speed. The resonant wave motions for linear and nonlinear, rotating disks are simulated numerically for a 3.5-inch diameter computer memory disk.

Creep Tests of Rotating Disks at Elevated Temperature and Comparison With Theory

1954 ◽  
Vol 21 (3) ◽  
pp. 225-235
Author(s):  
A. M. Wahl ◽  
G. O. Sankey ◽  
M. J. Manjoine ◽  
E. Shoemaker
Keyword(s):  
Elevated Temperatures ◽  
Experimental Program ◽  
Test Results ◽  
Rotating Disks ◽  
Creep Tests ◽  
Shear Theory ◽  
Heat Treated ◽  
Long Time ◽  
Average Tension ◽  
Creep Deformations

Abstract A theoretical and experimental program involving methods of calculating creep in rotating disks at elevated temperatures is described. This program consisted primarily of the following: (a) Obtaining forged disks from the same ingot of 12 per cent chrome steel, all disks being forged and heat-treated in the same manner; (b) making spin tests at 1000 F on three of these disks for periods up to about 1000 hr; ( ) making long-time tension-creep tests at 1000 F on many specimens cut out circumferentially from several of the other disks at stresses approximating those of the spin tests; (d) investigating theoretical methods of calculation of creep deformation in such disks; and (e) comparison of spin-test results with those calculated theoretically using average tension-creep data. It was found that available methods of calculating rotating disks based on the Mises criterion gave creep deformations too low compared to the test values, i.e., on the unsafe side for design. Considerably better agreement between test and theoretical results is obtained if the latter is based on the maximum-shear theory. Some discussion is given of the reasons for the better agreement obtained using the latter theory; these are believed to be related in part to the anisotropy of the forged material tested. Further tests on other materials are necessary before general conclusions can be drawn; however, in the absence of test data it is suggested that a conservative course in design for such disks is to apply the maximum-shear theory.

scholarly journals Recent advancements in shape optimization of aero spiked high speed re-entry vehicle using CFD

2018 ◽  
Vol 172 ◽  
pp. 01007
Author(s):  
Harish Panjagala ◽  
E L N Rohit Madhukar ◽  
I Ravi Kiran
Keyword(s):  
High Speed ◽  
Structural Integrity ◽  
Elevated Temperatures ◽  
Thermal Protection ◽  
Space Vehicle ◽  
Protection Systems ◽  
Ultimate Outcome ◽  
Increasing Demand ◽  
Space Activities ◽  
Intense Heat

Due to increasing demand of High Speed Re-entry vehicles for Space activities within the world, a serious issue associated with the method of deceleration down a vehicle is by the intense heat generated because of development of stronger shocks at the nose. The price of thermal protection systems (TPS) to cut back the warmth generated by the return vehicles is extremely high. In this paper, the ultimate outcome is to cut back the aero heating which is achieved by introducing a spike at frontal region of the nose. Additionally, this spike avoids the deterioration and preserves the structural integrity of space vehicle over elevated temperatures. Further, four totally different geometries of tip specifically Blunt, Slender, Snap and Pan for the aerospike has been introduced and their impact on performance is evaluated and compared with the vehicle having TPS. Hence, usage of aerospike in return vehicles is the most successful and economical over different protection system.

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