The sensitivity analysis of a suspension seat dynamic model
The sensitivity analysis of a suspension seat dynamic model
The key objectives of this thesis were to develop a general non-linear theoretical model of a suspension seat and to use this model to quantify the effect of the seat component parts on the performance of a conventional suspension seat design using a relevant range of frequencies and magnitudes.
Wheeled off-road vehicles are capable of subjecting the operator to substantial amounts of whole-body vibration. Suspension seats are often fitted to this type of vehicle to reduce the vibration transmitted to the operator. Unfortunately, the need to limit the relative movement between the operator and the vehicle controls requires the seat stroke to be limited, usually using rubber buffers. The impacts as the suspension contacts these end-stops can result in more vibration on the seat surface than on the cab floor.
Non-linear simulation studies are potentially useful for investigating the performances of complex systems, but previous suspension seat simulations were tested over a limited range of conditions. This thesis describes the development of a non-linear theoretical model of a specific suspension seat and investigates the model performance in response to a systematic range of input frequencies, magnitudes and durations of realistic test motions.
Test motions were derived from cab floor vibration measurements from three off-road machines (an agricultural tractor, a forestry forwarder and an earthmover) in situations that commonly led to seat suspension end-stop impact events. The motions were observed to result in similar occurrence of end-stop impacts in the laboratory as observed in the field with the three vehicle seats. Laboratory tests also identified that the accepted procedure for measuring seat surface vibration can result in artefactual measurements on suspension seats if the occupant loses contact with the seat surface.
A general theoretical suspension seat model was developed using a non-linear lumped parameter approach. The dynamics of the component parts of the three seats were measured and a non-linear parameter optimisation process was developed to estimate the friction from the dynamic behaviour of the complete seat. The results of this process gave confidence in the performance of the model of the earthmover seat. The performance of the earthmover seat model was quantified by comparison with 673 laboratory measurements of the seat performance using the anthropodynamic dummy as the seat load. The model was found to predict the seat transmissibility (using the VDV-based SEAT value) to within 15% of the measured value in 81% of the tests.
University of Southampton
Gunston, Thomas Peter
25b3637a-856a-40fe-87dd-ff80eccbe753
2002
Gunston, Thomas Peter
25b3637a-856a-40fe-87dd-ff80eccbe753
Gunston, Thomas Peter
(2002)
The sensitivity analysis of a suspension seat dynamic model.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
The key objectives of this thesis were to develop a general non-linear theoretical model of a suspension seat and to use this model to quantify the effect of the seat component parts on the performance of a conventional suspension seat design using a relevant range of frequencies and magnitudes.
Wheeled off-road vehicles are capable of subjecting the operator to substantial amounts of whole-body vibration. Suspension seats are often fitted to this type of vehicle to reduce the vibration transmitted to the operator. Unfortunately, the need to limit the relative movement between the operator and the vehicle controls requires the seat stroke to be limited, usually using rubber buffers. The impacts as the suspension contacts these end-stops can result in more vibration on the seat surface than on the cab floor.
Non-linear simulation studies are potentially useful for investigating the performances of complex systems, but previous suspension seat simulations were tested over a limited range of conditions. This thesis describes the development of a non-linear theoretical model of a specific suspension seat and investigates the model performance in response to a systematic range of input frequencies, magnitudes and durations of realistic test motions.
Test motions were derived from cab floor vibration measurements from three off-road machines (an agricultural tractor, a forestry forwarder and an earthmover) in situations that commonly led to seat suspension end-stop impact events. The motions were observed to result in similar occurrence of end-stop impacts in the laboratory as observed in the field with the three vehicle seats. Laboratory tests also identified that the accepted procedure for measuring seat surface vibration can result in artefactual measurements on suspension seats if the occupant loses contact with the seat surface.
A general theoretical suspension seat model was developed using a non-linear lumped parameter approach. The dynamics of the component parts of the three seats were measured and a non-linear parameter optimisation process was developed to estimate the friction from the dynamic behaviour of the complete seat. The results of this process gave confidence in the performance of the model of the earthmover seat. The performance of the earthmover seat model was quantified by comparison with 673 laboratory measurements of the seat performance using the anthropodynamic dummy as the seat load. The model was found to predict the seat transmissibility (using the VDV-based SEAT value) to within 15% of the measured value in 81% of the tests.
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Published date: 2002
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Local EPrints ID: 464935
URI: http://eprints.soton.ac.uk/id/eprint/464935
PURE UUID: 2944e3d8-ca7b-46b1-90c2-587dc3c0bbe1
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Date deposited: 05 Jul 2022 00:12
Last modified: 16 Mar 2024 19:50
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Author:
Thomas Peter Gunston
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