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Investigation on plain journal bearings for severe working conditions

Bassani R., Ciulli E., Piccigallo B.

International Journal of Applied Mechanics and Engineering

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2005

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Vol. 10, no 3

423-439

EN

In this paper a theoretical and experimental work for design of plain journal bearing able to work up to severe conditions is reported. The mathematical model and the numerical methods on which a purposely developed computer program is based are firstly described. The program is aimed to the evaluation of the behaviour of hydrodynamic plain journal bearings under heavy static loads, considering the elastic deformation of the bearing members, geometrical errors such as the axis misalignŹment and thermal effects. The experimental apparatus designed and set up for testing plain bearings in several working conditions, by varying speed, load and oil supply up to extremely critical situations, is then briefly described. Theoretical and experimental results obtained at different load, speed and oil flow rate conditions are finally compared showing a good agreement.

2

Experimental research on hydrostatic bearing in hydraulic actuators

Bassani R., Ciulli E, Lorenzetti M.

International Journal of Applied Mechanics and Engineering

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2002

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Vol. 7, no 2

479-489

EN

Low fluid losses associated with low friction are an important target for every kind of sealing, in particular for hydraulic actuators. In this work an experimental study on a device with capillary compensated hydrostatic pistons is reported. Experimental results, mainly concern the flow rate and pressure determination for different conditions, show a quite good agreement with the theoretical ones. A possibility to improve the system has been found out.

3

Hydrostatic lubrication: the principle and applications of flow self-regulation

Bassani R.

Applied Mechanics and Engineering

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1999

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Vol. 4, no 2

291-310

EN

A concise outline is presented of the principle of self-regulated flow rate in hydrostatic lubrication and some interesting applications are described on kinematic pairs and their systems. The principle permits a continuous and automatic distribution of the total flow in partial constant flows in the recesses of hydrostatic bearings due to their special shape. Studies and results obtained and presented here refer to: - generalities of the principle, pointed out by a bearing, - self-regulated hydrostatic screw and nut, - self regulated hydrostatic screw and nut with rectangular threads, - system of self-regulated hydrostatic pads.

4

Analysis of a surface crack in rolling bearings

Bassani R., Ciulli E., Di Puccio F.

Applied Mechanics and Engineering

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1999

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Vol. 4, no spec.

305-310

EN

Surface cracks may be detrimental in rolling bearings life. The paper present a linear elastic fracture mechanics approach, based in the weight function method for evaluating the stress intensity factors history during a load cycle. The real contact problem is simplified to a half-plane with an angled crack, and a load travelling over it, due to ehd or hertzian pressure distribution. Moreover the effect of a tractive force is also considered, with a friction coefficient equal to -0.05. The method is rather simple requiring only nominal stresses in the body, easily achievable also in an analytical form, e.g. Applying kolosov-muskhelishvili complex variable approach. Results show that hertzian and ehd pressure distribution causes similar stress intensity factors cycles, even if the first case crack propagation seems to be favoured.