Determination of resonant stresses is an important step in the life estimation of turbomachine blades. Resonance may occur either at a steady operating speed or under transient conditions of operation when the blade passes through a critical speed. Damping plays a significant role in limiting the amplitudes of vibration and stress values. The blade damping mechanism is very complex in nature, because of interfacial slip, material hysteresis, and gas dynamic damping occurring simultaneously. In this paper, a numerical technique to compute the stress response of a turbine blade with nonlinear damping characteristics, during steady and transient operations of the rotor, is presented. Damping is defined as a function of vibratory mode, rotor speed, and strain amplitude. The technique is illustrated by computing the stress levels at resonant rotor speeds for typical operation of a turbomachine.
Issue Section:
Gas Turbines: Structures and Dynamics
Topics:
Blades,
Damping,
Stress,
Transients (Dynamics),
Resonance,
Rotors,
Turbomachinery,
Turbine blades,
Vibration
1.
Carnegie
W.
1957
, “Static Bending of Pre-twisted Cantilever Blading
,” Proc. Instn. Mech. Engrs.
, Vol. 171
, p. 873
873
.2.
Carnegie
W.
1967
, “The Application of the Variational Method to Derive the Equations of Motion of Vibrating Cantilever Blading Under Rotation
,” BMEE
, Vol. 6
, p. 29
29
.3.
Crawley
E. F.
1983
, “Aerodynamic Damping Measurement in a Transonic Fan
,” ASME JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER
, Vol. 105
, p. 575
575
.4.
Dym, C. L., and Shames, I. H., 1973, Solid Mechanics, A Variational Approach, McGraw-Hill, New York.
5.
Griffin, J. H., and Bielak, J., 1984, “Research on Friction Damping in Jet Engines at Carnegie Mellon University,” Proc. Vib. Damping Workshop, Long Beach, AD-A152, p. M-1.
6.
Hammons, T. J., 1982, “Electrical Damping and Its Effect on Accumulative Fatigue Life Expenditure of Turbine-Generator Shafts Following Worst Case Supply System Disturbances,” University of Glasgow, United Kingdom, IEEE.
7.
Irretier, H., 1986, “Transient Vibrations of Turbine Blades Due to Passage Through Partial Admission and Nozzle Excitation Resonances,” Proc. IFToMM Intl. Conf. Rotor Dynamics, Tokyo, p. 301.
8.
Jones, D. I. G., and Muszynska, A., 1983, “A Discrete Model of a Multiple Blade System With Interblade Slip,” Vibrations of Blades and Bladed Disk Assemblies, ASME, p. 137.
9.
Lagnese, T. J., and Jones, D. I. G., 1983, “Measurement and Analysis of Platform Damping in Advanced Turbine Blade Response,” Proc. Shock Vib. Bull., US Naval Res. Labs., Proc. 53, Pt. 4, p. 19.
10.
Lazan, B. T., 1968, Damping of Materials and Members in Structural Mechanics, Pergamon Press, New York.
11.
MacBain
J. C.
Whaley
P. W.
1984
, “Maximum Resonant Response of Mistuned Bladed Disks
,” ASME Journal of Vibration, Acoustics, Stress, and Reliability in Design
, Vol. 106
, p. 218
218
.12.
Ostachowics, W., and Szwedowic, D., 1986, “Vibrations of Beams With Elastic Contact,” Computers Struc., p. 763.
13.
Providakis, C. P., and Beskos, D. E., 1986, “Dynamic Analysis of Beams by the Boundary Element Method,” Computers Struc., p. 957.
14.
Rao, J. S., Gupta, K., and Vyas, N. S., 1986a, “Blade Damping Measurement in a Spin Rig With Nozzle Passing Excitation Simulated by Electromagnets,” Proc. Shock Vib. Bull., US Naval Res. Labs., Proc. 56, Pt. 2, p. 109.
15.
Rao, J. S., Gupta, K., and Vyas, N. S., 1986b, “Analytical and Experimental Investigations on Vibratory Stresses of a Rotating Steam Turbine Blade Under NPF Excitation,” Proc. IFToMM Intl. Conf. Rotor Dynamics, Tokyo, p. 269.
16.
Rieger, N. F., and Beck, L. C., 1980, “Dynamic Tests on Turbine Blades,” EPRI Project Report, RP-1185-2.
17.
Rieger, N. F., 1984, “Damping Properties of Steam Turbine Blades,” Proc. Vib. Damping Workshop, Long Beach, AD-A152, 547, p. 2-1.
18.
Roark, R. J., and Young, W. C., 1976, “Formulas for Stress and Strain,” McGraw-Hill, New York.
19.
Sinha
A.
Griffin
J. H.
1984
, “Effects of Static Friction on the Forced Response of Frictionally Damped Turbine Blades
,” ASME JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER
, Vol. 106
, p. 65
65
.20.
Srinivasan
A. V.
Cutts
D. G.
1983
, “Dry Friction Damping Mechanisms in Engine Blades
,” ASME JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER
, Vol. 105
, p. 332
332
.21.
Usmani, M. A. W., 1986, “Interface Damping in Blade Attachment Region,” Ph.D. Thesis, IIT, New Delhi, India.
22.
Vyas, N. S., 1986, “Vibratory Stress Analysis and Fatigue Life Estimation of Turbine Blades,” Ph.D. Thesis, IIT, New Delhi, India.
23.
Vyas, N. S., Gupta, K., and Rao, J. S., 1987, “Transient Response of Turbine Blade,” Proc. 7th IFToMM World Congress, Sevilla, Spain, p. 697.
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