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| 2. |
- Lopez Arteaga, Ines, et al.
(författare)
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Energy dissipation of a friction damper
- 2004
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Ingår i: Journal of Sound and Vibration. - : Elsevier BV. - 0022-460X .- 1095-8568. ; 278:3, s. 539-561
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Tidskriftsartikel (refereegranskat)abstract
- In this paper the energy dissipated through friction is analysed for a type of friction dampers used to reduce squeal noise from railway wheels. A one degree-of-freedom system is analytically studied. First the existence and stability of a periodic solution are demonstrated and then the energy dissipated per cycle is determined as a function of the system parameters. In this way the influence of the mass, natural frequency and internal damping of the friction damper on the energy dissipation is established. It is shown that increasing the mass and reducing the natural frequency and internal damping of the friction damper maximizes the dissipated energy.
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| 3. |
- Lopez Arteaga, Ines, et al.
(författare)
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Friction dampers, the positive side of friction
- 2004
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Ingår i: Proceedings of the 2004 International Conference on Noise and Vibration Engineering, ISMA. - 9789073802827 ; , s. 589-601
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Friction is frequently seen as an unwanted phenomenon whose influence has to be either minimised or controlled. In this work one of the positive sides of friction is investigated: friction damping. Friction dampers can be a cheap and efficient way to reduce the vibration levels of a wide range of mechanical systems. Here the energy dissipated through friction is analysed for a type of friction dampers used to reduce squeal noise from railway wheels. Three different 1DOF systems of increasing complexity are analytically studied and simple non-dimensional expressions are derived for the optimal friction force and energy dissipation. In this way the influence of the mass, natural frequency and internal damping of the friction damper on the energy dissipation is established. It is shown that increasing the mass and reducing the natural frequency and internal damping of the friction damper maximises the dissipated energy.
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| 4. |
- Lopez Arteaga, Ines, et al.
(författare)
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Theoretical analysis of ring damped railway wheels
- 2000
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Ingår i: Shock and Vibration Digest. - 0583-1024 .- 1741-3184. ; 32:1
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Tidskriftsartikel (refereegranskat)abstract
- Ring-dampers for railway wheels can be very effective in suppressing squeal noise. An effort is made to understand the mechanisms by which damping is provided. The main aspects of wheel/ring interaction are studied in a simple single-degree-of-freedom system. A model of the nonlinear forces acting at the wheel-ring interface is developed. The large computing time needed for the time domain (TD) analysis makes it impractical to use for the parametric analysis of the wheel/ring system. Therefore, an approximate TD model is developed.
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| 6. |
- Vael, G.E.M., et al.
(författare)
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Reducing flow pulsation with the floating cup pump : theoretical analysis
- 2004
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Ingår i: Bath Workshop on Power Transmission and Motion Control (PTMC 2004). - 1860584667 ; , s. 123-141
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- With the recent introduction of the floating cup (FC) displacement principle, axial piston units can be realised using low cost mass production techniques instead of the more machine shop type of production techniques used to date. As a consequence, a far larger number of displacement volumes can be realised at the same or lower unit costs. An obvious advantage of a larger number of pistons is the reduction of flow pulsation from the unit. This paper focuses on this flow pulsation. In the ideal theoretical case that two out of phase halves of an FC pump directly deliver to the pump outlet, the odd harmonics in the 12 piston based flows from each pump half, will cancel out totally. In reality however, both sides are connected by a duct of finite length. The geometry of that duct and the location of the pump outlet, can significantly influence both the 'external' flow pulsation - at the pump outlet - and the 'internal' flow pulsation - in the duct. The paper shows that if the outlet duct is arranged symmetrical with respect to the two pump halves, perfect cancellation of the odd harmonics is indeed reached but only at the cost of high resonant pressure peaks within the duct. These pressure peaks might cause pump noise. They can be attenuated by either arranging the outlet in a non-symmetrical position or by adding Helmholtz resonators to the duct. Both options were studied; both show potential.
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