The Influence of Porosity on the Dynamic Characteristics of Porous Air Bearings
R.M. Burghoorn (TU Delft - Mechanical Engineering)
R. Van Ostayen – Mentor (TU Delft - Mechatronic Systems Design)
Joep Nijssen – Graduation committee member (ASML)
Jack van der Sanden – Graduation committee member (ASML)
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Abstract
Air bearings are a vital component to high tech machines and have been in widespread use since the 1960s. They provide near frictionless motion, have high stiffness and a near infinite lifetime. When looking at existing literature the influence of the porosity on the dynamic characteristics has not been researched in depth. Especially when looking at porous air bearings with a surface restrictive layer, a discrepancy can be defined between the ideal surface restrictive layers considered in literature and layers that can be realized in reality. This report presents a model to accurately predict the dynamic characteristics of both bearings with and without a surface restrictive layer. An alternative intuitive
approach is presented to explain the dynamic behaviour at low frequencies for these types of bearing based on the amount of stored air inside and underneath the bearing. This model is then used to investigate the influence of the porosity on the dynamic characteristics of a uncoated bearing. Followed by a study on the mechanics behind the surface restrictive layers and the sensitivity of the porosity of the surface restrictive layer. An existing dataset from an experiment is used to asses the viability of the model.