Title page for ETD etd-07022003-102302


Type of Document Master's Thesis
Author Norris, James Alexander
Author's Email Address jnorris@vt.edu
URN etd-07022003-102302
Title Behavior of Magneto-Rheological Fluids Subject to Impact and Shock Loading
Degree Master of Science
Department Mechanical Engineering
Advisory Committee
Advisor Name Title
Ahmadian, Mehdi Committee Chair
Johnson, Martin E. Committee Member
Leo, Donald Committee Member
Keywords
  • mr damper
  • magnetorheological
  • drop tower
  • dynamic response
  • impulsive
  • shock absorber
Date of Defense 2003-06-19
Availability unrestricted
Abstract
Investigations on the design of controllable magnetorheological (MR) fluid devices have focused heavily on low velocity and low frequency applications. The extensive work in this area has led to a good understanding of MR fluid properties at low velocities and frequencies. However, the issues concerning MR fluid behavior in impact and shock applications are relatively unknown.

To investigate MR fluid properties in this regime, MR dampers were subjected to impulsive loads. A drop-tower test facility was developed to simulate the impact events. The design includes a guided drop-mass released from variable heights to achieve different impact energies. Five drop-heights and two fundamental MR damper configurations were tested. The two configurations were a double-ended piston and a mono-tube with nitrogen accumulator. To separate the dynamics of the MR fluid from the dynamics of the current source, each damper received a constant supply current before the impact event. A total of five supply currents were investigated for each impact velocity.

After reviewing the results, it was concluded that the effect of energizing the MR fluid only leads to “controllability” below a certain fluid velocity for the double-ended design. In other words, until the fluid velocity dropped below some threshold, the MR fluid behaved as if it was not energized, regardless of the strength of the magnetic field. Controllability was defined when greater supply currents yielded larger damping forces.

For the mono-tube design, it was shown that the MR fluid was unable to travel through the gap fast enough during the initial impact. Consequently, the damper piston and accumulator piston traveled in unison until the accumulator bottomed out. After which, the fluid was forced through the gap.

In conclusion, the two designs were compared and general recommendations on designing MR dampers for impulsive loading were made. Possible directions for future research were presented as well.

Files
  Filename       Size       Approximate Download Time (Hours:Minutes:Seconds) 
 
 28.8 Modem   56K Modem   ISDN (64 Kb)   ISDN (128 Kb)   Higher-speed Access 
  01_Cover_Page.pdf 47.61 Kb 00:00:13 00:00:06 00:00:05 00:00:02 < 00:00:01
  02_Abstract.pdf 65.42 Kb 00:00:18 00:00:09 00:00:08 00:00:04 < 00:00:01
  03_Acknowledgements.pdf 57.63 Kb 00:00:16 00:00:08 00:00:07 00:00:03 < 00:00:01
  04_Body.pdf 2.78 Mb 00:12:53 00:06:37 00:05:48 00:02:54 00:00:14
  05_Appendix_A.pdf 3.26 Mb 00:15:05 00:07:45 00:06:47 00:03:23 00:00:17
  06_Appendix_B.pdf 2.26 Mb 00:10:28 00:05:23 00:04:42 00:02:21 00:00:12
  07_Appendix_C.pdf 662.06 Kb 00:03:03 00:01:34 00:01:22 00:00:41 00:00:03
  08_Vita.pdf 101.73 Kb 00:00:28 00:00:14 00:00:12 00:00:06 < 00:00:01

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