 |
 |
Journal articles
Parametrically excited helicopter ground resonance dynamics with high blade asymmetries
Abstract : The present work is aimed at verifying the influence of high asymmetries in the variation of in-plane lead-lag stiffness of one blade on the ground resonance phenomenon in helicopters. The periodical equations of motions are analyzed by using Floquet's Theory (FM) and the boundaries of instabilities predicted. The stability chart obtained as a function of asymmetry parameters and rotor speed reveals a complex evolution of critical zones and the existence of bifurcation points at low rotor speed values. Additionally, it is known that when treated as parametric excitations; periodic terms may cause parametric resonances in dynamic systems, some of which can become unstable. Therefore, the helicopter is later considered as a parametrically excited system and the equations are treated analytically by applying the Method of Multiple Scales (MMS). A stability analysis is used to verify the existence of unstable parametric resonances with first and second-order sets of equations. The results are compared and validated with those obtained by Floquet's Theory. Moreover, an explanation is given for the presence of unstable motion at low rotor speeds due to parametric instabilities of the second order.
Keywords :
Ground resonance
Cited literature [17 references]
https://hal.archives-ouvertes.fr/hal-00772189
Contributor : Open Archive Toulouse Archive Ouverte (oatao) <>
Submitted on : Thursday, January 10, 2013 - 10:54:30 AM
Last modification on : Tuesday, September 8, 2020 - 6:28:05 PM
Long-term archiving on: : Thursday, April 11, 2013 - 3:53:59 AM
Contributor : Open Archive Toulouse Archive Ouverte (oatao) <>
Submitted on : Thursday, January 10, 2013 - 10:54:30 AM
Last modification on : Tuesday, September 8, 2020 - 6:28:05 PM
Long-term archiving on: : Thursday, April 11, 2013 - 3:53:59 AM
File
Alazard_8076.pdf
Files produced by the author(s)