Author: Michael J. Rutkowski
Publisher:
ISBN:
Category : Helicopters
Languages : en
Pages : 86
Book Description
The dynamic coupling between the rotor system and the fuselage of a simplified helicopter model in hover is analytically investigated. Mass, aerodynamic damping, and elastic and centrifugal stiffness matrices are presented for the analytical model; the model is based on a beam finite element, with polynomial mass and stiffness distributions for both the rotor and fuselage representations. For this analytical model, only symmetric fuselage and collective blade degrees of freedom are treated. Real and complex eigen-analyses are carried out to obtain coupled rotor-fuselage natural modes and frequencies as a function of rotor speed. Vibration response results are obtained are the coupled system subjected to a radially uniform, harmonic blade loading. The coupled response results are compared with response results from an uncoupled analysis in which hub loads for an isolated rotor system subjected to the same sinusoidal blade loading as the coupled system are applied to a free-free fuselage. It is shown that although the fuselage response as a function of forcing frequency and rotor speed is similar in the two cases, the responses resulting from the approximate, uncoupled analysis are significantly greater than those resulting from the coupled analysis.
The Vibration Characteristics of a Coupled Helicopter Rotor-fuselage by a Finite Element Analysis
Author: Michael J. Rutkowski
Publisher:
ISBN:
Category : Helicopters
Languages : en
Pages : 86
Book Description
The dynamic coupling between the rotor system and the fuselage of a simplified helicopter model in hover is analytically investigated. Mass, aerodynamic damping, and elastic and centrifugal stiffness matrices are presented for the analytical model; the model is based on a beam finite element, with polynomial mass and stiffness distributions for both the rotor and fuselage representations. For this analytical model, only symmetric fuselage and collective blade degrees of freedom are treated. Real and complex eigen-analyses are carried out to obtain coupled rotor-fuselage natural modes and frequencies as a function of rotor speed. Vibration response results are obtained are the coupled system subjected to a radially uniform, harmonic blade loading. The coupled response results are compared with response results from an uncoupled analysis in which hub loads for an isolated rotor system subjected to the same sinusoidal blade loading as the coupled system are applied to a free-free fuselage. It is shown that although the fuselage response as a function of forcing frequency and rotor speed is similar in the two cases, the responses resulting from the approximate, uncoupled analysis are significantly greater than those resulting from the coupled analysis.
Publisher:
ISBN:
Category : Helicopters
Languages : en
Pages : 86
Book Description
The dynamic coupling between the rotor system and the fuselage of a simplified helicopter model in hover is analytically investigated. Mass, aerodynamic damping, and elastic and centrifugal stiffness matrices are presented for the analytical model; the model is based on a beam finite element, with polynomial mass and stiffness distributions for both the rotor and fuselage representations. For this analytical model, only symmetric fuselage and collective blade degrees of freedom are treated. Real and complex eigen-analyses are carried out to obtain coupled rotor-fuselage natural modes and frequencies as a function of rotor speed. Vibration response results are obtained are the coupled system subjected to a radially uniform, harmonic blade loading. The coupled response results are compared with response results from an uncoupled analysis in which hub loads for an isolated rotor system subjected to the same sinusoidal blade loading as the coupled system are applied to a free-free fuselage. It is shown that although the fuselage response as a function of forcing frequency and rotor speed is similar in the two cases, the responses resulting from the approximate, uncoupled analysis are significantly greater than those resulting from the coupled analysis.
The Vibration Characteristics of a Coupled Helicopter Rotor-fuselage by a Finite Element Analysis
Author: Michael J. Rutkowski
Publisher:
ISBN:
Category : Helicopters
Languages : en
Pages : 84
Book Description
Publisher:
ISBN:
Category : Helicopters
Languages : en
Pages : 84
Book Description
Sensitivity Analysis of Torsional Vibration Characteristics of Helicopter Rotor Blades. Part 1: Structural Dynamics Analysis
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 54
Book Description
A theoretical investigation of structural vibration characteristics of rotor blades was carried out. Coupled equations of motion for flapwise bending and torsion were formulated for rotor blades with noncollinear elastic and mass axes. The finite element method was applied for a detailed representation of blade structural properties. Coupled structural mass and stiffness coefficients were evaluated. The range of validity of a set of coupled equations of motion linearized with respect to eccentricity between elastic and mass axes was investigated. The sensitivity of blade vibration characteristics to torsion were evaluated by varying blade geometric properties, boundary conditions, and eccentricities between mass and elastic axes.
Publisher:
ISBN:
Category :
Languages : en
Pages : 54
Book Description
A theoretical investigation of structural vibration characteristics of rotor blades was carried out. Coupled equations of motion for flapwise bending and torsion were formulated for rotor blades with noncollinear elastic and mass axes. The finite element method was applied for a detailed representation of blade structural properties. Coupled structural mass and stiffness coefficients were evaluated. The range of validity of a set of coupled equations of motion linearized with respect to eccentricity between elastic and mass axes was investigated. The sensitivity of blade vibration characteristics to torsion were evaluated by varying blade geometric properties, boundary conditions, and eccentricities between mass and elastic axes.
The Shock and Vibration Digest
Author:
Publisher:
ISBN:
Category : Shock (Mechanics)
Languages : en
Pages : 84
Book Description
Publisher:
ISBN:
Category : Shock (Mechanics)
Languages : en
Pages : 84
Book Description
Sensitivity Analysis of Torsional Vibration Characteristics of Helicopter Rotor Blades
Author: Theodore Bratanow
Publisher:
ISBN:
Category : Rotors (Helicopters)
Languages : en
Pages : 52
Book Description
Publisher:
ISBN:
Category : Rotors (Helicopters)
Languages : en
Pages : 52
Book Description
NASA Technical Paper
Author:
Publisher:
ISBN:
Category : Science
Languages : en
Pages : 84
Book Description
Publisher:
ISBN:
Category : Science
Languages : en
Pages : 84
Book Description
A Coupled Rotor-fuselage Vibration Analysis for Helicopter Rotor System Fault Detection
Author: Mao Yang
Publisher:
ISBN:
Category : Fault location (Engineering)
Languages : en
Pages : 564
Book Description
Publisher:
ISBN:
Category : Fault location (Engineering)
Languages : en
Pages : 564
Book Description
Correlation of Ah-1g Airframe Flight Vibration Data with a Coupled Rotor-Fuselage Analysis
Author: National Aeronautics and Space Administration (NASA)
Publisher: Createspace Independent Publishing Platform
ISBN: 9781723548345
Category :
Languages : en
Pages : 228
Book Description
The formulation and features of the Rotor-Airframe Comprehensive Analysis Program (RACAP) is described. The analysis employs a frequency domain, transfer matrix approach for the blade structural model, a time domain wake or momentum theory aerodynamic model, and impedance matching for rotor-fuselage coupling. The analysis is applied to the AH-1G helicopter, and a correlation study is conducted on fuselage vibration predictions. The purpose of the study is to evaluate the state-of-the-art in helicopter fuselage vibration prediction technology. The fuselage vibration predicted using RACAP are fairly good in the vertical direction and somewhat deficient in the lateral/longitudinal directions. Some of these deficiencies are traced to the fuselage finite element model. Sangha, K. and Shamie, J. Unspecified Center NASA-CR-181974, NAS 1.26:181974 NAS1-17498; RTOP 505-63-51-01...
Publisher: Createspace Independent Publishing Platform
ISBN: 9781723548345
Category :
Languages : en
Pages : 228
Book Description
The formulation and features of the Rotor-Airframe Comprehensive Analysis Program (RACAP) is described. The analysis employs a frequency domain, transfer matrix approach for the blade structural model, a time domain wake or momentum theory aerodynamic model, and impedance matching for rotor-fuselage coupling. The analysis is applied to the AH-1G helicopter, and a correlation study is conducted on fuselage vibration predictions. The purpose of the study is to evaluate the state-of-the-art in helicopter fuselage vibration prediction technology. The fuselage vibration predicted using RACAP are fairly good in the vertical direction and somewhat deficient in the lateral/longitudinal directions. Some of these deficiencies are traced to the fuselage finite element model. Sangha, K. and Shamie, J. Unspecified Center NASA-CR-181974, NAS 1.26:181974 NAS1-17498; RTOP 505-63-51-01...
The Rotating Beam Problem in Helicopter Dynamics
Author: Ranjan Ganguli
Publisher: Springer
ISBN: 9811060983
Category : Technology & Engineering
Languages : en
Pages : 109
Book Description
The book addresses computational methods for solving the problem of vibration, response, loads and stability of a helicopter rotor blade modeled as a rotating beam with flap or out-of-plane bending. The focus is on explaining the implementation of the finite element method in the space and time domain for the free vibration, aeroelastic response and stability problems. The use of Floquet analysis for the aeroelastic stability analysis of rotor blades is also shown. The contents of the book will be useful to researchers in aerodynamics and applied mechanics, and will also serve well professionals working in the aerospace industry.
Publisher: Springer
ISBN: 9811060983
Category : Technology & Engineering
Languages : en
Pages : 109
Book Description
The book addresses computational methods for solving the problem of vibration, response, loads and stability of a helicopter rotor blade modeled as a rotating beam with flap or out-of-plane bending. The focus is on explaining the implementation of the finite element method in the space and time domain for the free vibration, aeroelastic response and stability problems. The use of Floquet analysis for the aeroelastic stability analysis of rotor blades is also shown. The contents of the book will be useful to researchers in aerodynamics and applied mechanics, and will also serve well professionals working in the aerospace industry.
Coupled Rotor/fuselage Dynamic Analysis of the AH-1G Helicopter and Correlation with Flight Vibrations Data
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 156
Book Description
Publisher:
ISBN:
Category :
Languages : en
Pages : 156
Book Description