Showing papers by "Terenziano Raparelli published in 1999"
TL;DR: In this paper, the journal equation of motion and the complete Reynolds equation of compressible fluid film are numerically solved and a computer program is developed to obtain journal center trajectories and effects of fluid inertia.
Abstract: The journal equation of motion and the complete Reynolds equation of compressible fluid film are numerically solved and a computer program is developed. The formulas are for externally pressurized bearings, but results are shown only for self-acting bearings. For certain cases, the validity of the theoretical results is verified by comparison with the experimental data available from the literature. Through intensive use of the program, journal center trajectories are obtained and effects of fluid inertia are investigated. New stability parameters are presented and stability diagrams are established for bearings with L/D = 0.25, 0.5, 1, 1.5, and 2. The rotor unbalance effects on bearing stability limits are illustrated for several cases.
36 citations
01 Jan 1999
TL;DR: In this article, a modification of the McKibben pneumatic muscle, following the idea of a research group from the University of Warsaw, is implemented and manufactured, which consists of asilicon bladder that is attached at either end to fittings; it has the shape of a tube.
Abstract: In this paper a modification of the McKibben pneumatic muscle, following the idea of a research group from the University of Warsaw, is implemented and manufactured. The muscle consists of asilicon bladder that is attached at either end to fittings; it has the shape of a tube. Inside the silicon bladder longitudinal high resistance cables are inserted with some circular rings. When the internal bladder is pressurised the actuator shorten. A Finite Element Modelling, using the Mooney-Rivlin formulation with two coefficients for the rubber and with truss elements for the longitudinal cables of the muscle, is used to forecast its behaviour. A prototype has been manufactured. A test bed has been developed to measure the mechanical characteristics of the actuator. The results of the comparison between the model and the prototype are presented and discussed. The F.E. model optimised in this way can be used to design every shape of this kind of pneumatic muscle actuator and to define simplified design procedure.
6 citations
01 Jan 1999
TL;DR: In this paper, a theoretical and experimental investigation of sealless pistons with a special profile for reducing friction in pneumatic cylinders is presented, followed by the flow rate equations written using a one-dimensional flow model.
Abstract: The paper presents a theoretical and experimental investigation of sealless pistons with a special profile for reducing friction in pneumatic cylinders. A description of system geometry is followed by the flow rate equations written using a one-dimensional flow model. The axial pressure distribution and the self-centering force on the piston are then determined. The influence of design parameters on system performance is evaluated, and test results are presented for three pistons of the same length and featuring steps of the same height but located in a different axial position. Theoretical results are compared with the experimental data.
5 citations