MAGNETO-RHEOLOGICAL (MR) DAMPER FOR
LANDING GEAR SYSTEM
Mahboubeh Khani
A Thesis
in
the Department
of
Mechanical and Industrial Engineering
Presented in Partial Fulfillment of
the
Requirements
for the Degree of Master of Applied Science (Mechanical Engineering) at
Concordia University
Montreal, Quebec, Canada
June 2010
© Mahboubeh Khani, 2010
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ABSTRACT
Magneto-Rheological (MR) Damper for Landing Gear System
Mahboubeh Khani
Depending on the different sink speeds, angles of attack and masses; aircraft
landing gears could face a wide range of impact conditions which may possibly cause
structural damage or failure. Thus, in hard landing scenarios, the landing gear must
absorb sufficient energy in order to minimize dynamic stress on the aircraft airframe.
Semi-active control systems are the recent potential solutions to overcome these
limitations. Among semi-active control strategies, those based on smart fluids such as
magneto-rheological (MR) fluids have received recent attraction as their rheological
properties can be continuously controlled using magnetic or electric field and they are not
sensitive to the contaminants and the temperature variation and also require lower
powers.
This thesis focuses on modeling of a MR damper for landing gear system and
analysis of semi-active controller to attenuate dynamic load and landing impact. First,
passive landing gear of a Navy aircraft is modeled and the forces associated with the
shock strut are formulated. The passive shock strut is then integrated with a MR valve to
design MR shock strut.
Ill
Here, MR shock strut is integrated with the landing gear system modeled as the
2DOF system and governing equations of motion are derived in order to simulate the
dynamics of the system under different impact conditions. Subsequently the inverse
model of the MR shock strut relating MR yield stress to the MR shock strut force and
strut velocity is formulated. Using the developed governing equations and inverse model,
a PID controller is formulated to reduce the acceleration of the system. Controlled
performance of the simulated MR landing gear system is demonstrated and compared
with that of passive system.
IV
ACKNOWLEDGMENTS
First, I would like to pay my great appreciation to my supervisors, Dr. Ion Stiharu and Dr.
Ramin Sedaghati for their endless amount of moral support and encouragement along
with their practical opinions throughout the thesis work.
The financial support by Mechanical and Industrial Engineering Department of
Concordia University is acknowledged.
I also would like to extend my thanks to my colleagues, MR. Arash Firoozrai and MR.
Amin Changizi, for their collaborations.
Finally, I would like to dedicate this thesis to my beloved husband, Majid Fekri, my
parents, Masi Hassan zadeh and Eino Khani and my sisters, Marzi, Leila and Zara Khani
who have always been there for me throughout my life with their love, support, advice
and encouragement.
V