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Controllable suspension design using magnetorheological fluid
Dissertation (MEng)--University of Pretoria, 2013.
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| Format: | Thesis |
| Language: | English |
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University of Pretoria
2013
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| _version_ | 1867613662443732992 |
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| access_status_str | Open Access |
| author2 | Els, P.S. (Pieter Schalk) |
| author_browse | Els, P.S. (Pieter Schalk) |
| author_facet | Els, P.S. (Pieter Schalk) |
| collection | Thesis |
| dc_rights_str_mv | © 2013 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. |
| description | Dissertation (MEng)--University of Pretoria, 2013. |
| format | Thesis |
| id | oai:repository.up.ac.za:2263/32545 |
| institution | University of Pretoria (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:39:42.666Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UPSpace — University of Pretoria Institutional Repository |
| publishDate | 2013 |
| publishDateRange | 2013 |
| publishDateSort | 2013 |
| publisher | University of Pretoria |
| publisherStr | University of Pretoria |
| record_format | dspace |
| source_str | UPSpace — University of Pretoria Institutional Repository |
| spelling | oai:repository.up.ac.za:2263/32545 Controllable suspension design using magnetorheological fluid Els, P.S. (Pieter Schalk) Kaul, Sudhir Strydom, Anria Vehicle Dynamics UCTD Controllable magnetorheological (MR) dampers Passive hydro-pneumatic spring-damper units Dissertation (MEng)--University of Pretoria, 2013. The purpose of this study is to mitigate the compromise between ride comfort and handling of a small single seat off-road vehicle known as a Baja. This has been achieved by semi-active control of the suspension system containing controllable magnetorheological (MR) dampers and passive hydro-pneumatic spring-damper units. MR fluid is a viscous fluid whose rheological properties depend on the strength of the magnetic field surrounding the fluid, and typically consists of iron particles suspended in silicone oil. When a magnetic field is applied to the fluid, the iron particles become aligned and change the effective viscosity of the fluid. The use of MR fluid in dampers provides variable damping that can be changed quickly by controlling the intensity of the magnetic field around the fluid. Various benefits associated with the use of MR dampers have led to their widespread implementation in automotive engineering. Many studies on conventional vehicles in the existing literature have demonstrated the conflicting suspension requirements for favourable ride comfort and handling. Generally, soft springs with low damping are ideal for improved ride comfort, while stiff springs with high damping are required for enhanced handling. This has resulted in the development of passive suspension systems that provide either an enhanced ride quality or good drivability, often targeting one at the expense of the other. The test vehicle used for this study is distinct in many ways with multiple characteristics that are not commonly observed in the existing literature. For instance, the absence of a differential in the test vehicle driveline causes drivability issues that are aggravated by increased damping. The majority of existing MR damper models in the literature are developed for uniform excitation and re-characterisation of model parameters is required for changes in input conditions. Although recursive models are more accurate and applicable to a wider range of input conditions, these models require measured force feedback which may not always be available due to limitations such as packaging constraints. These constraints required the development of alternative MR damper models that can be used to prescribe the current input to the damper. In this study parametric, nonparametric and recursive MR damper models have been developed and evaluated in terms of accuracy, invertibility and applicability to random excitation. The MR damper is used in parallel with passive damping as a certain amount of passive damping is always present in suspension systems due to friction and elastomeric parts. Most of the existing studies on suspension systems have been performed using linear two degree of freedom vehicle models that are constrained to specific conditions. Usually these models are implemented without an indication of the ability of these models to accurately represent the vehicles that these studies are intended for. For this study, a nonlinear, three-dimensional, 12 degrees of freedom vehicle model has been developed to represent the test vehicle. This model is validated against experimental results for ride comfort and handling. The MR damper models are combined with the model of the test vehicle, and used in ride comfort and handling simulations at various levels of passive damping and control gains in order to assess the potential impact of suspension control on the ride quality and drivability of the test vehicle. Simulation results show that lower passive damping levels can significantly improve the ride comfort as well as the handling characteristics of the test vehicle. Furthermore, it is observed that additional improvements that may be obtained by the implementation of continuous damping control may not be justifiable due to the associated cost and complexity. Mechanical and Aeronautical Engineering unrestricted 2013-11-21T06:26:37Z 2013-11-21T06:26:37Z 2013 2013 Dissertation Strydom, A. 2013. Controllable Suspension Design Using Magnetorheological Fluid, MEng dissertation, University of Pretoria, Pretoria, viewed yymmdd<http://hdl.handle.net/2263/32545> http://hdl.handle.net/2263/32545 en © 2013 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. application/pdf University of Pretoria |
| spellingShingle | Vehicle Dynamics UCTD Controllable magnetorheological (MR) dampers Passive hydro-pneumatic spring-damper units Controllable suspension design using magnetorheological fluid |
| title | Controllable suspension design using magnetorheological fluid |
| title_full | Controllable suspension design using magnetorheological fluid |
| title_fullStr | Controllable suspension design using magnetorheological fluid |
| title_full_unstemmed | Controllable suspension design using magnetorheological fluid |
| title_short | Controllable suspension design using magnetorheological fluid |
| title_sort | controllable suspension design using magnetorheological fluid |
| topic | Vehicle Dynamics UCTD Controllable magnetorheological (MR) dampers Passive hydro-pneumatic spring-damper units |
| url | http://hdl.handle.net/2263/32545 |