Vibration Isolation: Use and Characterization

Abstract

This article is concerned with vibration isolation, with antivibration mountings (resilient isolators), and with the static and dynamic properties of rubberlike materials that are suited for use in antivibration mountings. The design of practical antivibration mounts incorporating rubber or coiled-steel springs is described in Refs. 1–27; pneumatic isolators (air mounts, etc.) are described in Refs. 5, 28–35. Throughout the literature, as here, attention is focussed predominantly on the translational (vertical) effectiveness of antivibration mountings. However, the two- and three-dimensional vibration of one- or two-stage mounting systems is addressed in Refs. 4, 10, 12, 36–56. Following a description of the static and dynamic properties of rubberlike materials, the performance of the simple or one-stage mounting system is analyzed, account being taken of the occurrence of second-order resonances in the isolator and in the mounted item. In the latter case, as likely in practice, the bulk of the mounted item is assumed to remain masslike, whereas the feet of the item are assumed to be nonrigid (multiresonant). Discussion is then given to the two-stage or compound mounting system, which affords superior vibration isolation at high frequencies. Subsequently, the powerful four-pole parameter technique is employed to analyze, in general terms, the performance of an antivibration mounting with second-order resonances (wave effects) when both the foundation that supports the mounting system and the machine are nonrigid. The universally adopted method of measuring mount transmissibility is then described, followed by an explanation of how transmissibility can also be determined by four-pole parameter techniques based on an apparatus used by Schloss. The four-pole measurement approach has not been exploited hitherto, but it is apparently feasible and valuable because it enables mounts to be tested under compressive loads equal to those routinely encountered in service.

The Role of Studs in the Sound Transmission of Double Walls

“…The study of the connection type has been omitted but this is an important issue that should be analysed by means of three-dimensional models [7]. The literature review of Section 2 reveals that resilient devices tested in the laboratory are usually characterised by means of a four-pole parameter analysis [23] (also called two-port parameter analysis in [28]), but double wall models usually consider the stud to be a translational or rotational elastic spring.…”

“…Most of the techniques were originally developed in order to determine the properties of rubber-like materials that are used as vibration isolators. An extensive literature review can be found in [23]. The consequence of this background is a set of ISO regulations establishing the basis of this kind of measurements [24].…”

Hybrid viscous damper with filtered integral force feedback control

“…Supplemental passive dampers (Fu and Kazai, 1998;Sorace and Terenzi, 2008) and base-isolation systems (Snowdon, 1979) are used in many aspects of structural engineering for mitigation of excessive dynamic response (Symans et al, 2008). However, improved damping performance compared to the passive case may be obtained by combining pure energy dissipating installations with active elements to form so-called active/passive or hybrid damper systems (Thenozhi and Yu, 2013).…”

Suspended Decoupler: A New Design of Hydraulic Engine Mount

“…The engine is the largest concentrated mass in a vehicle and causes vibration if it is not properly isolated and constrained. The trend for many years to isolate vibrations was to simply connect the engine and frame by means of an engine mount made of elastomeric materials such as rubber [1][2][3]. Modeling the rubber isolator by a linear system and considering a base excited single-degree-offreedom system, we know in the frequency response curves of the acceleration transmitted to the isolated mass there exists a crossing point at a frequency ratio value of ω/ω n = 2 1/2 in which all the curves representing systems with differing damping ratios converge [4].…”