Design and analysis of high-frequency periodically layered isolators for helicopter gearbox isolation

Research output: Chapter in Book/Report/Conference proceedingConference contribution

4 Citations (Scopus)

Abstract

Vibration generation by meshing gear pairs is a significant source of vibration and cabin noise in rotorcraft transmissions. This tonal, high-frequency gearbox noise (500 Hz - 2000 Hz) is primarily transmitted to the fuselage through rigid connections, which do not appreciably attenuate vibratory energy. Because periodically-layered elastomer and metal isolators exhibit transmissibility "stop bands", or frequency ranges in which there is very low transmissibility, they may provide an elegant passive vibration control solution. Realistic design constraints associated with helicopter gearbox isolator mass, axial stiffness, and elastomeric fatigue are estimated. An optimization routine is then used in concert with design constraints and an axisymmetric isolator model to determine layered isolator passive performance limits. The optimization results suggest that layered isolators cannot always be designed to meet target frequencies given a certain set of constraints. Therefore, passive performance enhancements to layered isolators are considered. The use of embedded fluid elements in the metal layers results in a combination of advantageous performance benefits, including motion amplification and vibration absorber effects. The enhanced layered isolators are capable of passively providing broadband noise attenuation, as well as dramatic attenuation at discrete problematic tones.

Original languageEnglish (US)
Title of host publication44th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference
StatePublished - Dec 1 2003
Event44th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference 2003 - Norfolk, VA, United States
Duration: Apr 7 2003Apr 10 2003

Publication series

Name44th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference

Other

Other44th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference 2003
CountryUnited States
CityNorfolk, VA
Period4/7/034/10/03

Fingerprint

Helicopters
Fuselages
Vibration control
Metals
Elastomers
Chemical elements
Amplification
Gears
Stiffness
Fatigue of materials
Fluids

All Science Journal Classification (ASJC) codes

  • Civil and Structural Engineering
  • Mechanics of Materials
  • Building and Construction
  • Architecture

Cite this

Szefi, J. T., Smith, E. C., & Lesieutre, G. A. (2003). Design and analysis of high-frequency periodically layered isolators for helicopter gearbox isolation. In 44th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference (44th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference).
Szefi, Joseph T. ; Smith, Edward C. ; Lesieutre, George A. / Design and analysis of high-frequency periodically layered isolators for helicopter gearbox isolation. 44th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference. 2003. (44th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference).
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Szefi, JT, Smith, EC & Lesieutre, GA 2003, Design and analysis of high-frequency periodically layered isolators for helicopter gearbox isolation. in 44th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference. 44th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference, 44th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference 2003, Norfolk, VA, United States, 4/7/03.

Design and analysis of high-frequency periodically layered isolators for helicopter gearbox isolation. / Szefi, Joseph T.; Smith, Edward C.; Lesieutre, George A.

44th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference. 2003. (44th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference).

Research output: Chapter in Book/Report/Conference proceedingConference contribution

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N2 - Vibration generation by meshing gear pairs is a significant source of vibration and cabin noise in rotorcraft transmissions. This tonal, high-frequency gearbox noise (500 Hz - 2000 Hz) is primarily transmitted to the fuselage through rigid connections, which do not appreciably attenuate vibratory energy. Because periodically-layered elastomer and metal isolators exhibit transmissibility "stop bands", or frequency ranges in which there is very low transmissibility, they may provide an elegant passive vibration control solution. Realistic design constraints associated with helicopter gearbox isolator mass, axial stiffness, and elastomeric fatigue are estimated. An optimization routine is then used in concert with design constraints and an axisymmetric isolator model to determine layered isolator passive performance limits. The optimization results suggest that layered isolators cannot always be designed to meet target frequencies given a certain set of constraints. Therefore, passive performance enhancements to layered isolators are considered. The use of embedded fluid elements in the metal layers results in a combination of advantageous performance benefits, including motion amplification and vibration absorber effects. The enhanced layered isolators are capable of passively providing broadband noise attenuation, as well as dramatic attenuation at discrete problematic tones.

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Szefi JT, Smith EC, Lesieutre GA. Design and analysis of high-frequency periodically layered isolators for helicopter gearbox isolation. In 44th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference. 2003. (44th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference).