Noise and Vibration Reduction in Felt Mountings

Abstract

Resonant curves of loaded felt pads in compressional vibration give values for the damping and dynamic stiffness which show that felt in vibration is quite different from an equivalent perfect spring with viscous damping. The un-symmetrical resonance curves and the fact that, within experimental error, the stiffness is inversely proportional to the square root of the thickness indicate a decrease in stiffness with increasing amplitude. The increase in stiffness with pressure is so large that the ratio of dynamic elastic modulus to pressure (stiffness over mass) does not vary greatly between pressures of three to one hundred pounds per square inch. In this range the natural frequency of a mass on a felt pad is determined by the thickness of the pad rather than by its area and static load. An analysis of the performance of felt in reducing vibration transmission shows that its effectiveness is limited in most cases to frequencies above forty cycles per second. Practical installations have been studied and tables drawn up to give the acoustical engineer “handbook” information for the solution of problems in vibration reduction.

A comprehensive optimal design method for magnetorheological dampers utilized in DMU power package

“…In early stage, a single-layer anti-vibration system was applied to suppress power package's broadband vibration. 1–3 According to the study carried out by Hardy and Tyzzer, 4 Li et al 5 and Luo et al 6 , single-layer system has limited suppression efficiency and cannot deal with the complex and high-amplitude vibration, despite its advantage of simple structure. Then a double-layer anti-vibration system is introduced, where an intermediate mass elastically supported is inserted between the power unit and the vehicle body.…”

Performance evaluation of a novel intelligent distributed mounting system for marine mechanical equipment

“…Distributed intermediate mass is made of rigid metal block with larger stiffness and small size, which is beneficial to improve vibration isolation efficiency of mounting system. 5 –8…”

“…Distributed intermediate mass is made of rigid metal block with larger stiffness and small size, which is beneficial to improve vibration isolation efficiency of mounting system. [5][6][7][8] Numerous researchers and engineers have been involved in the study of floating-rafting mounting system. The machinery floating raft were used on the main engine and auxiliary machinery of US Sea-wolf and Virginia class nuclear submarine and impressive vibration isolation effectiveness were achieved.…”