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The dynamic stiffness of an air-spring

Pelz, Peter F. ; Buttenbender, Johannes (2022)
The dynamic stiffness of an air-spring.
International Conference on Noise and Vibration Engineering 2004. Leuven, Belgium (20.-22.09.2004)
doi: 10.26083/tuprints-00020949
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Item Type: Conference or Workshop Item
Type of entry: Secondary publication
Title: The dynamic stiffness of an air-spring
Language: English
Date: 2022
Place of Publication: Darmstadt
Year of primary publication: 2004
Publisher: Katholieke Univ. Leuven, Dep. Werktuigkunde
Book Title: Proceedings of ISMA2004 : Noise and Vibration Engineering
Event Title: International Conference on Noise and Vibration Engineering 2004
Event Location: Leuven, Belgium
Event Dates: 20.-22.09.2004
DOI: 10.26083/tuprints-00020949
Corresponding Links:
Origin: Secondary publication service

The measurement of the dynamic stiffness of an air spring identifies a behaviour which up until now is not fully understood. Depending on whether the compression is isothermal or adiabatic the dynamic stiffness differs by a factor of 1.4 for a perfect diatomic gas. The frequency band in which the stiffness increase takes place is determined by the heat conduction from the compressed air to the air-spring wall. Since the heat transport is diffusive, the change of stiffness happens to be in a surprisingly low frequency band, ranging between 0.001 Hz and 0.1 Hz for a typical vehicle air spring. To understand this dynamic behaviour in detail, i.e. to find the temperature distribution within the spring, the energy equation must be solved using the momentum and mass balance simultaneously. This is done in an analytic manner by considering only small disturbances from the initial pressure, temperature, and density, when the air is at rest. The results show that an oscillating temperature boundary layer is formed in which the heat conduction takes places. With increasing dimensionless frequency, i.e. Peclet number, the boundary-layer thickness decreases and the stiffness approaches its adiabatic value. In theory there is no need to use a heat transfer coefficient. Furthermore the theory serves as a way to determine the heat transfer coefficient. The dimensionless transfer coefficient, i.e. the Nusselt number, is useful when only the average temperature and pressure are of interest. This is usually the case when the air spring is considered as a connecting part between different masses in a dynamic system. It is found that the Nusselt number for the heat conduction inside the air spring is a constant ( 0.3≈Nu ).

Status: Publisher's Version
URN: urn:nbn:de:tuda-tuprints-209496
Classification DDC: 600 Technology, medicine, applied sciences > 620 Engineering and machine engineering
Divisions: 16 Department of Mechanical Engineering > Institute for Fluid Systems (FST) (since 01.10.2006)
Date Deposited: 09 May 2022 11:08
Last Modified: 29 Mar 2023 12:07
URI: https://tuprints.ulb.tu-darmstadt.de/id/eprint/20949
PPN: 495511919
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