The effect of underplatform dampers on the forced response of bladed disks by a coupled static/dynamic harmonic balance method

Abstract Friction contacts are often used in turbomachinery design as passive damping systems. In particular, underplatform dampers are mechanical devices used to decrease the vibration amplitudes of bladed disks. Numerical codes are used to optimize during designing the underplatform damper effectiveness in order to limit the resonant stress level of the blades. In such codes, the contact model plays the most relevant role in calculation of the dissipated energy at friction interfaces. One of the most important contact parameters to consider in order to calculate the forced response of blades assembly is the static normal load acting at the contact, since its value strongly affects the area of the hysteresis loop of the tangential force, and therefore the amount of dissipation. A common procedure to estimate the static normal loads acting on underplatform dampers consists in decoupling the static and the dynamic balance of the damper. A preliminary static analysis of the contact is performed in order to get the static contact/gap status to use in the calculation, assuming that it does not change when vibration occurs. In this paper, a novel approach is proposed. The static and the dynamic displacements of the system (bladed disk+underplatform dampers) are coupled together during the forced response calculation. Static loads acting at the contacts follow from static displacements and no preliminary static analysis of the system is necessary. The proposed method is applied to a numerical test case representing a simplified bladed disk with underplatform dampers. Results are compared with those obtained with the classical approach.

[1]  C. Menq,et al.  STICK–SLIP–SEPARATION ANALYSIS AND NON-LINEAR STIFFNESS AND DAMPING CHARACTERIZATION OF FRICTION CONTACTS HAVING VARIABLE NORMAL LOAD , 1998 .

[2]  Jörgen Wildheim.  VIBRATIONS OF ROTATING CIRCUMFERENTIALLY PERIODIC STRUCTURES , 1981 .

[3]  Christian Maria Firrone,et al.  Modeling a friction damper: analysis of the experimental data and comparison with numerical results , 2006 .

[4]  David J. Ewins,et al.  Modal Testing: Theory, Practice, And Application , 2000 .

[5]  D. J. Ewins,et al.  Analytical Formulation of Friction Interface Elements for Analysis of Nonlinear Multi-Harmonic Vibrations of Bladed Disks , 2003 .

[6]  Chia-Hsiang Menq,et al.  Characterization of Contact Kinematics and Application to the Design of Wedge Dampers in Turbomachinery Blading: Part 1—Stick-Slip Contact Kinematics , 1998 .

[7]  Walter Sextro,et al.  Spatial Dynamics of Tuned and Mistuned Bladed Disks with Cylindrical and Wedge-Shaped Friction Dampers , 2003 .

[8]  Stefano Zucca,et al.  Range of variability in the dynamics of semi-cylindrical friction dampers for turbine blades. , 2008 .

[9]  Chia-Hsiang Menq,et al.  Characterization of Contact Kinematics and Application to the Design of Wedge Dampers in Turbomachinery Blading: Part 2—Prediction of Forced Response and Experimental Verification , 1998 .

[10]  E. P. Petrov.  Explicit Finite Element Models of Friction Dampers in Forced Response Analysis of Bladed Discs , 2007 .

[11]  David J. Ewins,et al.  Underplatform Dampers for Turbine Blades: Theoretical Modeling, Analysis, and Comparison With Experimental Data , 2001 .

[12]  Ning An,et al.  Forced Response Prediction of Constrained and Unconstrained Structures Coupled Through Frictional Contacts , 2009 .

[13]  D. J. Ewins,et al.  Advanced Modeling of Underplatform Friction Dampers for Analysis of Bladed Disk Vibration , 2007 .

[14]  Walter Sextro,et al.  Optimization of Interblade Friction Damper Design , 2000 .

[15]  C. Menq,et al.  Characterization of 3D contact kinematics and prediction of resonant response of structures having 3D frictional constraint , 1998 .

[16]  Evgeny Petrov,et al.  Explicit Finite Element Models of Friction Dampers in Forced Response Analysis of Bladed Disks , 2008 .

[17]  E. P. Petrov.  A Method for Use of Cyclic Symmetry Properties in Analysis of Nonlinear Multiharmonic Vibrations of Bladed Disks (2003-GT-38480) , 2004 .

[18]  Herbert Jericha,et al.  Design Concept for Large Output Graz Cycle Gas Turbines , 2006 .

[19]  Walter Sextro,et al.  Asymmetrical Underplatform Dampers in Gas Turbine Bladings: Theory and Application , 2004 .

[20]  Gabor Csaba,et al.  Modelling of a Microslip Friction Damper Subjected to Translation and Rotation , 1999 .

[21]  Jörg Wallaschek,et al.  Multiharmonic Forced Response Analysis of a Turbine Blading Coupled by Nonlinear Contact Forces , 2010 .

[22]  J. Szwedowicz,et al.  Numerical and Experimental Damping Assessment of a Thin-Walled Friction Damper in the Rotating Setup With High Pressure Turbine Blades , 2006 .