The University of Southampton
University of Southampton Institutional Repository

Shock isolation systems incorporating Coulomb friction

Shock isolation systems incorporating Coulomb friction
Shock isolation systems incorporating Coulomb friction
This study investigates a novel approach to the problem of shock isolation. The questions considered are whether friction produces a better performance in terms of reduced response during a shock compared to viscous damping and a lower residual response after the shock.

To gain physical insight, a single degree of freedom model with friction applied to the isolated mass is analysed. It serves as a benchmark to the performance of a two degree of freedom model where friction is applied to a secondary mass. The isolation system performance is then quantified. For the two degree of freedom system with an intermediate secondary spring which connects the primary and secondary mass, it is possible to obtain the reduction in the displacement response as good as the single degree of freedom system and at the same time smoother acceleration response compared to the single degree of freedom system. For the purpose of further improvement, a control strategy is introduced to switch on and off friction in both models depending on some response parameters and this is compared to the passive systems. This is the semi active control strategy where friction is changed within a cycle of vibration (discontinuous). The control strategy provides more displacement reduction to ensure the maximum displacement response is much smaller than the base input which cannot be obtained with the passive systems.

The practical implementation and experimental validation is presented only for the first stage of the response during the shock. For the practical implementation of the switchable friction, an electromagnet is applied to separate the friction surfaces. Good agreement with the simple theoretical models for both passive and switchable systems is obtained. The reduced displacement and smooth acceleration response were obtained from the experiments with the system used to represent the two degree of freedom model. The issues and limitations in the practical implementation are identified and discussed.
Ismail, Mohd
e05c5c4a-b671-4d65-b372-0f5836a7aa92
Ismail, Mohd
e05c5c4a-b671-4d65-b372-0f5836a7aa92
Ferguson, Neil
8cb67e30-48e2-491c-9390-d444fa786ac8

(2012) Shock isolation systems incorporating Coulomb friction. University of Southampton, Faculty of Engineering and the Environment, Doctoral Thesis, 243pp.

Record type: Thesis (Doctoral)

Abstract

This study investigates a novel approach to the problem of shock isolation. The questions considered are whether friction produces a better performance in terms of reduced response during a shock compared to viscous damping and a lower residual response after the shock.

To gain physical insight, a single degree of freedom model with friction applied to the isolated mass is analysed. It serves as a benchmark to the performance of a two degree of freedom model where friction is applied to a secondary mass. The isolation system performance is then quantified. For the two degree of freedom system with an intermediate secondary spring which connects the primary and secondary mass, it is possible to obtain the reduction in the displacement response as good as the single degree of freedom system and at the same time smoother acceleration response compared to the single degree of freedom system. For the purpose of further improvement, a control strategy is introduced to switch on and off friction in both models depending on some response parameters and this is compared to the passive systems. This is the semi active control strategy where friction is changed within a cycle of vibration (discontinuous). The control strategy provides more displacement reduction to ensure the maximum displacement response is much smaller than the base input which cannot be obtained with the passive systems.

The practical implementation and experimental validation is presented only for the first stage of the response during the shock. For the practical implementation of the switchable friction, an electromagnet is applied to separate the friction surfaces. Good agreement with the simple theoretical models for both passive and switchable systems is obtained. The reduced displacement and smooth acceleration response were obtained from the experiments with the system used to represent the two degree of freedom model. The issues and limitations in the practical implementation are identified and discussed.

PDF
thesis-Mohd Ikmal Ismail.pdf - Other
Download (4MB)

More information

Published date: July 2012
Organisations: University of Southampton, Inst. Sound & Vibration Research

Identifiers

Local EPrints ID: 348953
URI: http://eprints.soton.ac.uk/id/eprint/348953
PURE UUID: fe0083a0-4e6f-4c0a-8d02-b918928682cd
ORCID for Neil Ferguson: ORCID iD orcid.org/0000-0001-5955-7477

Catalogue record

Date deposited: 06 Mar 2013 14:07
Last modified: 06 Jun 2018 13:18

Export record

Contributors

Author: Mohd Ismail
Thesis advisor: Neil Ferguson ORCID iD

University divisions

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of http://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×