Showing papers on "Active vibration control published in 1968"

Roll with vibration damping means

Abstract: 1,187,326. Rollers; vibration dampers. MOUNT HOPE MACHINERY Ltd. 21 May, 1968, No. 24055/68. Headings F2S and F2U. Vibration of a heavy roller comprising a stationary hollow axle 10 carrying a rotatable sleeve 12 on fluid bearings 14 or, Fig. 3 (not shown), on roller bearings (76), is damped by a paddle 70 resiliently mounted in the hollow axle. As shown, the paddle is mounted by resilient rods 68 in blocks 64 mounted on a tension rod 56 which gives the roller an initial curvature prior to application of the load. The axle is partially filled with water or other lubricating fluid and the paddle acts to pump the fluid through the clearance between itself and the axle to dampen vibration of the roller. The paddle is tuned to a natural frequency equal to that of the roller. Again, Fig. 5 (not shown), the paddle is mounted on a tension bar 56 at its centre only, tuning masses being mounted at its end. The paddle may be formed as a laminate, e.g. in the manner of a leafspring, and vibrational energy of the roller absorbed additionally by interfacial friction between the discrete layers of the laminated paddle as it vibrates.

Transduction, control and measurement of vibration in vibratory apparatus

Abstract: A method and apparatus for transducing the amplitude of vibration of a mechanical vibratory device into electrical energy, using a field effect transistor. Preferably an accelerometer is mounted on the device and oriented for relative oscillation in the direction of vibration.

Feasibility Study of a Hybrid Vibration Isolation System

Abstract: : The fluctuating lift of a helicopter rotor gives rise to undesirable vibration over a broad frequency range which in some cases may extend to as low as 3 Hz. Vibration isolation over this frequency range is very difficult to achieve with either a purely passive or an active vibration isolation system. A passive system will work well at high frequencies, but it will always have a low-frequency resonance where excitation will be amplified rather than reduced. An active system may work well at low frequencies, but it will have trouble meeting the frequency response requirements at high frequencies. The investigation of the feasibility of combining an active and a passive system was conducted to gain the advantages of both. The report shows that an active system may be used to control the resonant response of a passive system while preserving the isolation achieved at high frequencies. Isolation over a broad frequency range may be obtained by this means with only a small amplification of response at low frequencies.