Title page for ETD etd-07032006-175710


Document Type Master's Dissertation
Author Janse van Rensburg, Neil
URN etd-07032006-175710
Document Title Time delay in a semi-active damper
Degree MEng (Mechanical Engineering)
Department Mechanical and Aeronautical Engineering
Supervisor
Advisor Name Title
Prof J L Steyn Committee Chair
Keywords
  • hydraulic valve mathematical models
  • springs and suspension
  • automobiles
Date 2001-04-01
Availability unrestricted
Abstract
In this study the feasibility of two mathematical models of the dynamics of a hydraulic bypass valve used on semi-active suspension systems for heavy vehicles is investigated. It is envisaged that similar models will eventually be incorporated into a full vehicle, three dimensional simulation study. The valve system contains an electro-hydraulic pilot valve circuit, a logic element, a damper and four check valves in a rectifier configuration.

Models were compiled from first principles in the MATLAB environment and with the commercial fluid power simulation software, AMESim. The numerical methods used in the MATLAB model were found to be incapable of solving the stiff, nonlinear and discontinuous governing equations efficiently, while AMESim is very capable of handling detailed and complex fluid power models.

Experimental work was conducted to determine certain steady state model parameters and to obtain dynamic performance data with which to validate model integrity.

Several external factors influenced the valve behaviour during experiments making data extraction challenging. Simple first order assumptions accounting for the external influences on the valve therefore had to be included in the models. If this is done the basic dynamic behaviour of the valve system is matched well by the models. In general, the number of unknown parameters associated with fluid power systems accounted for the largest portion of the error between the simulated and measured response.

The model as developed proved the possibility of creating highly accurate models but also indicated the amount of effort needed for their compilation.

2000, University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria.

Please cite as follows:

Janse van Rensburg, N 2000, Time delay in a semi-active damper, MEng dissertation, University of Pretoria, Pretoria, viewed yymmdd < http://upetd.up.ac.za/thesis/available/etd-07032006-175710/ >

H542/ag

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