Effect of Friction on the Performance of an Octostrut Vibration Isolation Platform

2008 ◽  
Vol 130 (5) ◽  
Author(s):  
L. He ◽  
L. K. Liu ◽  
L. Liang ◽  
G. T. Zheng
Keyword(s):  
Friction Force ◽  
Harmonic Balance ◽  
Vibration Isolation ◽  
Dynamic Environment ◽  
Harmonic Balance Method ◽  
Excitation Amplitude ◽  
Experimental Results ◽  
Force Model ◽  
Hysteresis Model ◽  
Isolation Frequency

To improve the dynamic environment of a spacecraft, an octostrut vibration isolation platform is designed to replace the payload attach fitting, which can significantly attenuate the vibration transmitted to payload except that an extra isolation frequency is introduced. However, it is found from the experimental results that when the excitation amplitude is lower than a certain level, the first resonance occurs at a higher frequency (i.e., the isolation frequency). This is caused by the nonlinearity that is a result of the friction existing in every actuator. Therefore, in this paper, the friction force of the single actuator is taken into account and is described by a bilinear hysteresis model. With this friction force model, a new nonlinear model of the octostrut vibration isolation platform is established. Meanwhile, the harmonic balance method is used to solve the nonlinear equations. The theoretical and experimental results indicate that the friction plays an important role in the performance of the platform. It is identified from the study that to ensure the performance of an isolator, in its design, either the maximum friction force or the minimum excitation should be restricted.

Forced Response Prediction of Blades With Loosely Assembled Dovetail Attachment by HBM

2009 ◽  
Author(s):  
Shangguan Bo ◽  
Zili Xu ◽  
Qilin Wu ◽  
XianDing Zhou ◽  
ShouHong Cao
Keyword(s):  
Friction Force ◽  
Centrifugal Force ◽  
Dry Friction ◽  
Harmonic Balance ◽  
Harmonic Balance Method ◽  
Forced Response ◽  
Balance Method ◽  
Force Model ◽  
Equivalent Stiffness ◽  
Equivalent Damping

To understand the mechanism of interfacial damping of axial loosely assembled dovetail to suppress blade vibration, a dry friction force model is presented by the Coulomb friction law and the macroslip model, and the mathematical expression of the friction force is derived. The nonlinear friction force is linearized as an equivalent stiffness and an equivalent damping through the one-term harmonic balance method. The effect of centrifugal force on the equivalent stiffness and the equivalent damping is studied. The forced response of one simplified blade with loosely assembled dovetail attachment is predicted by the harmonic balance method, in which the blade is described by the lumped mass and spring model, and the friction contact joints is simplified as a ideal friction damper. The results show that the equivalent stiffness of loosely assembled dovetail attachment increases with blade centrifugal force, gradually reaches a certain value, and there exists the maximum value for the equivalent stiffness. The equivalent damping increases at the beginning and then decreases with blade centrifugal force increasing, there exists a maximum too. The resonant frequency of blade rises with blade centrifugal force, but it no longer increases when the centrifugal force exceed a certain value. There exists a special centrifugal force on which the effect of dry friction damping is the best.

scholarly journals Validation of Friction Model Parameters Identified Using the IHB Method Using Finite Element Method

2019 ◽  
Vol 2019 ◽  
pp. 1-19
Author(s):  
Abdallah Hadji ◽  
Njuki Mureithi
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Friction Force ◽  
Harmonic Balance ◽  
Harmonic Balance Method ◽  
Friction Model ◽  
Balance Method ◽  
Model Parameters ◽  
Friction Models ◽  
Element Method

A hybrid friction model was recently developed by Azizian and Mureithi (2013) to simulate the friction behavior of tube-support interaction. However, identification and validation of the model parameters remains unresolved. In previous work, the friction model parameters were identified using the reverse harmonic method, where the following quantities were indirectly obtained by measuring the vibration response of a beam: friction force, sliding speed of the force of impact, and local displacement at the contact point. In the present work, the numerical simulation by the finite element method (FEM) of a beam clamped at one end and simply supported with the consideration of friction effect at the other is conducted. This beam is used to validate the inverse harmonic balance method and the parameters of the friction models identified previously. Two static friction models (the Coulomb model and Stribeck model) are tested. The two models produce friction forces of the correct order of magnitude compared to the friction force calculated using the inverse harmonic balance method. However, the models cannot accurately reproduce the beam response; the Stribeck friction model is shown to give the response closest to experiments. The results demonstrate some of the challenges associated with accurate friction model parameter identification using the inverse harmonic balance method. The present work is an intermediate step toward identification of the hybrid friction model parameters and, longer-term, improved analysis of tube-support dynamic behavior under the influence of friction.

scholarly journals Numerical simulation of the non-uniform flow in a full-annulus multi-stage axial compressor with the harmonic balance method

2020 ◽  
Vol 12 (3) ◽  
pp. 168781401989721 ◽  
Author(s):  
Haiou Sun ◽  
Meng Wang ◽  
Zhongyi Wang ◽  
Song Wang ◽  
Franco Magagnato
Keyword(s):  
Flow Field ◽  
Harmonic Balance ◽  
Axial Compressor ◽  
Harmonic Balance Method ◽  
Internal Flow ◽  
Uniform Flow ◽  
Experimental Results ◽  
Balance Method ◽  
Operating Characteristics ◽  
Multi Stage

To improve the understanding of unsteady flow in modern advanced axial compressor, unsteady simulations on full-annulus multi-stage axial compressor are carried out with the harmonic balance method. Since the internal flow in turbomachinery is naturally periodic, the harmonic balance method can be used to reduce the computational cost. In order to verify the accuracy of the harmonic balance method, the numerical results are first compared with the experimental results. The results show that the internal flow field and the operating characteristics of the multi-stage axial compressor obtained by the harmonic balance method coincide with the experimental results with the relative error in the range of 3%. Through the analysis of the internal flow field of the axial compressor, it can be found that the airflow in the clearance of adjacent blade rows gradually changes from axisymmetric to non-axisymmetric and then returns to almost completely axisymmetric distribution before the downstream blade inlet, with only a slight non-axisymmetric distribution, which can be ignored. Moreover, the slight non-axisymmetric distribution will continue to accumulate with the development of the flow and, finally, form a distinct circumferential non-uniform flow field in latter stages, which may be the reason why the traditional single-passage numerical method will cause certain errors in multi-stage axial compressor simulations.

scholarly journals Modeling of Friction Contact and its Application to the Design of Shroud Contact

1996 ◽  
Author(s):  
Been-Der Yang ◽  
Chia-Hsiang Menq
Keyword(s):  
Friction Force ◽  
Normal Load ◽  
Turbine Blades ◽  
Harmonic Balance Method ◽  
Forced Response ◽  
Effective Stiffness ◽  
Force Model ◽  
Friction Forces ◽  
Friction Joint ◽  
Stiffness And Damping

Designers of aircraft engines frequently employ shrouds in turbine design. In this paper, a variable normal load friction force model is proposed to investigate the influence of shroud-like contact kinematics on the forced response of frictionally constrained turbine blades. Analytical criteria are formulated to predict the transitions between slick, slip, and separation of the interface so as to assess the induced friction forces. When considering cyclic loading, the induced friction forces are combined with the variable normal load so as to determine the effective stiffness and damping of the friction joint over a cycle of motion. The harmonic balance method is then used to impose the effective stiffness and damping of the friction joint on the linear structure. The solution procedure for the nonlinear response nf a two-degree-of-freedom oscillator is demonstrated. As an application, this procedure is used to study the coupling effect of two constrained forces, friction force and variable normal load, on the optimization of the shroud contact design.

Characterization of Contact Kinematics and Application to the Design of Wedge Dampers in Turbomachinery Blading: Part 1—Stick-Slip Contact Kinematics

1998 ◽  
Vol 120 (2) ◽  
pp. 410-417 ◽  
Author(s):  
B. D. Yang ◽  
C. H. Menq
Keyword(s):  
Friction Force ◽  
Harmonic Balance Method ◽  
Forced Response ◽  
Operating Conditions ◽  
Force Model ◽  
Blade Vibration ◽  
Stick Slip ◽  
Friction Forces ◽  
Contact Kinematics ◽  
Stiffness And Damping

Friction dampers are often used in turbine design to attenuate blade vibration to acceptable levels so as to prolong blades’ service life. A wedge damper, also called a self-centering, blade-to-blade damper, can provide more design flexibility to meet various needs in different operating conditions when compared with conventional platform dampers. However, direct coupling of the two inclined friction interfaces of the wedge damper often leads to very complex contact kinematics. In Part I of this two-part paper, a dual-interface friction force model is proposed to investigate the coupling contact kinematics. The key issue of the model formulation is to derive analytical criteria for the stick-slip transitions that can be used to precisely simulate the complex stick-slip motion and, thus, the induced friction force as well. When considering cyclic loading, the induced periodic friction forces can be obtained to determine the effective stiffness and damping of the interfaces over a cycle of motion. In Part II of this paper, the estimated stiffness and damping are then incorporated with the harmonic balance method to predict the forced response of a blade constrained by wedge dampers.

scholarly journals Dynamic analysis and experiment of QZS system with nonlinear hysteretic damping

2021 ◽  
Author(s):  
Xiaoying Hu ◽  
Chunyan Zhou
Keyword(s):  
Vibration Isolation ◽  
Harmonic Balance Method ◽  
Nonlinear Damping ◽  
Primary Response ◽  
Nonlinear Phenomena ◽  
Isolation Frequency ◽  
Hysteretic Damping ◽  
Isolation Systems ◽  
The One ◽  
Vibration Tests

Abstract Nonlinear Quasi-zero-stiffness (QZS) vibration isolation systems with linear damping cannot lead to displacement isolation with different excitation levels. In this study, a QZS system with nonlinear hysteretic damping was investigated. The Duffing-Ueda equation with a coupling nonlinear parameter 𝜂 was proposed to describe the dynamic motion of the QZS system. By using the harmonic balance method (HBM), the primary and secondary harmonic responses were obtained and verified by numerical simulations. The results indicated that nonlinear damping can guarantee a bounded response for different excitation levels. The one-third subharmonic response was found to affect the isolation frequency range even when the primary response was stable. To evaluate the performance of the QZS system, the effective isolation frequency Ω𝑒 and maximum transmissibility 𝑇𝑝 were proposed to represent the vibration isolation range and isolation effect, respectively. By discussing the effect of 𝜂 on Ω𝑒 and 𝑇𝑝, the conditions to avoid nonlinear phenomena and improve the isolation performance are provided. A prototype of the QZS system was then constructed for vibration tests, which verified the theoretical analysis.

Validation of Friction Model Parameters Identified Using the Inverse Harmonic Balance Method

2015 ◽  
Author(s):  
Abdallah Hadji ◽  
Njuki Mureithi
Keyword(s):  
Friction Force ◽  
Harmonic Balance ◽  
Contact Point ◽  
Harmonic Balance Method ◽  
Friction Model ◽  
Balance Method ◽  
Model Parameters ◽  
Intermediate Step ◽  
Friction Forces ◽  
Friction Models

A hybrid friction model was recently developed by Azizian and Mureithi [1] to simulate the friction behavior of tube-support interaction. However, identification of the model parameters remains unresolved. In previous work, the friction model parameters were identified using reverse the harmonic method, where the following quantities were indirectly obtained by measuring the vibration response of a beam: friction force, sliding speed of the force of impact and local displacement at the contact point. In the present work, the simulation by the finite element method (FEM) of a beam clamped at one end and simply supported with the consideration of friction effect at the other is conducted. This beam is used to validate the inverse harmonic balance method and the parameters of the friction models identified previously. Two static friction models (the Coulomb model and Stribeck model) are tested. The two models produce friction forces of the correct order of magnitude compared to the friction force calculated using the inverse harmonic balance method. However, the models cannot accurately reproduce the beam response; the Stribeck friction model is shown to give the response closer to experiments. The results demonstrate some of the challenges associated with accurate friction model parameter identification using the inverse harmonic balance method. The present work is an intermediate step toward identification of the hybrid friction model parameters and, longer term, improved analysis of tube-support dynamic behavior under the influence of friction.

Performance of a friction ring DVA for vibration control of a flywheel

2021 ◽  
Vol 263 (4) ◽  
pp. 2449-2457
Author(s):  
Xiaodong He ◽  
Xiuchang Huang ◽  
Hongxing Hua
Keyword(s):  
Friction Force ◽  
Harmonic Balance ◽  
Degrees Of Freedom ◽  
Critical Frequency ◽  
Turning Point ◽  
Harmonic Balance Method ◽  
Damping Force ◽  
Vibration Absorption ◽  
Dynamic Vibration ◽  
Spring Force

A flexible ring DVA with friction contact interfaces (essentially a viscoelastic-friction DVA) is proposed to suppress vibration of a flywheel, two other cases are also studied, i.e., viscoelastic DVA and friction DVA. Based on an equivalent 3 degrees of freedom (DOFs) dynamic model, displacement response of the flywheel-DVA are obtained by using harmonic balance method (HBM). It is shown that all three types of DVA can suppress vibration of the flywheel effectively, bandwidth of the viscoelastic-friction DVA is enlarged due to the existence of friction interface. Performances of the DVA are evaluated by analyzing the displacement responses and forces (i.e., spring force, damping force and friction force). It is shown that the frequency corresponding to the turning point on the response curve is the critical frequency at which dynamic vibration absorption takes place, and it is also the frequency at which the friction force begins to take effect. In the process of emergence and disappearance of the dynamic vibration absorption, the friction force plays a role similar to a "switch"

Analysis of Chaotic Characteristics of the Strong Nonlinear Vibration Isolation System Based on Harmonic Balance Method

2014 ◽  
Vol 635-637 ◽  
pp. 117-122
Author(s):  
Wei Min Mao ◽  
Hui Zhang ◽  
Jing Jun Lou
Keyword(s):  
Nonlinear Equations ◽  
Harmonic Balance ◽  
Vibration Isolation ◽  
Harmonic Balance Method ◽  
Period Doubling ◽  
Isolation System ◽  
Runge Kutta Method ◽  
Chaotic Region ◽  
Response Range ◽  
Subharmonic Response

The key of studying the nonlinear system of the stationary period solutions by the HBM is solving a group of higher order multi-degree-of-freedom nonlinear equations. Aiming at this difficulty, this paper can easily get a higher harmonic balance truncation order expression of solution using a powerful symbolic computation software, and avoid the tedious derivation process. And the main subharmonic response range was accurately obtained by the EACM for solving the nonlinear equations. Meanwhile, the chaotic region was estimated through subharmonic cascade regions combined with the bifurcation of the Feigenbaum rule by solving the system. And, numerical results calculated by the Runge-Kutta method were given to verify the results of the period doubling bifurcations and chaotic region obtained by this method. It has been shown that they are in good agreement.

scholarly journals Characterization of Contact Kinematics and Application to the Design of Wedge Dampers in Turbomachinery Blading: Part I — Stick-Slip Contact Kinematics

1997 ◽  
Author(s):  
B. D. Yang ◽  
C. H. Menq
Keyword(s):  
Friction Force ◽  
Harmonic Balance Method ◽  
Forced Response ◽  
Operating Conditions ◽  
Force Model ◽  
Blade Vibration ◽  
Stick Slip ◽  
Friction Forces ◽  
Contact Kinematics ◽  
Stiffness And Damping

Friction dampers are often used in turbine design to attenuate blade vibration to acceptable levels so as to prolong blades’ service life. A wedge damper, also called a self-centering blade-to-blade damper, can provide more design flexibility to meet various needs in different operating conditions when compared with conventional platform dampers. However, direct coupling of the two inclined friction interfaces of the wedge damper often leads to very complex contact kinematics. In Part I of this two-part paper, a dual-interface friction force model is proposed to investigate the coupling contact kinematics. The key issue of the model formulation is to derive analytical criteria for the stick-slip transitions that can be used to precisely simulate the complex stick-slip motion and, thus, the induced friction force as well. When considering cyclic loading, the induced periodic friction forces can be obtained to determine the effective stiffness and damping of the interfaces over a cycle of motion. In Part II of this paper, the estimated stiffness and damping are then incorporated with the harmonic balance method to predict the forced response of a blade constrained by wedge dampers.

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