Vibration isolation

Vibration-isolation is the process of isolating an object, such as a piece of equipment, from the source

Passive isolation

Passive vibration isolation systems consist essentially of a mass, spring and damper (dash-pot).

The equipment and gears have joint with surrounding objects (the supporting joint - with the support; the unsupporting joint - the pipe duct or cable ).

[edit] Vibration-isolation of supporting joint

Vibration-isolation of supporting joint is realized in the device named vibration-isolator (absorber). On an illustration presented dependence of difference is levels of vibrations which are measured before installation of the functioning gear on vibration-isolator and after installation in a wide range of frequencies.

[edit] Vibration-isolator

Vibration-isolator – vibration- isolating device for reflection and absorption of waves of oscillatory energy, extending from the working gear or an electrical equipment, with the aid of effect of a vibration insulation. Vibration-isolator is established between a body transferring fluctuations and a body which defend (for example, between the gear and the foundation). On an illustration is presented the image vibration-isolator a series «ВИ» which are applied in shipbuilding of Russia. Shown «ВИ» allow loadings 5, 40 and 300 kg. They differ in the sizes, but have a similar structure . In a structure is used the rubber envelope, which is reinforced by a spring. Rubber and a spring are strongly connected during transformation of crude rubber into rubber envelope by a method of vulcanization. Under action of weight loading of the gear the rubber envelope is of deformation , and a spring are compressed or stretch. Thus, in springs cross section, occurs the twig twist with a material of rubber envelope, causing deformation of shift in rubber envelope. It is known, that the vibration insulation basically cannot be carried out without presence of vibration absorption . The size of deformation of shift in elastic material of isolator- vibration it basis for definition of size of absorption of fluctuations. At action of vibration or shock loadings of deformation increase. Being thus cyclic, it considerably strengthens efficiency of the given device. In the upper part of a design the sleeve, and in the lower part a flange by means of which the vibration-isolator fastens to the gear and the foundation.

[edit] Vibration-isolation of unsupporting joint

Vibration-isolation of unsupporting joint is realized in the device named branch pipe a of vibration-isolating.

[edit] A vibration-isolating branch pipe

A vibration-isolating branch pipe is a part of a tube with elastic walls for reflection and absorption of waves of the oscillatory energy extending from the working pump over wall of the pipe duct. Is established between the pump and the pipe duct. On an illustration is presented the image a vibration-isolating branch pipe of a series «ВИПБ». In a structure is used the rubber envelope, which is reinforced by a spring. Properties of a envelope are similar envelope to a vibration-isolator. Has the device reducing axial effort from action of internal pressure up to zero.

[edit] Active isolation

Active vibration isolation systems contain, along with the spring, a feedback circuit which consists of a piezoelectric accelerometer, a controller, and an electromagnetic transducer. The acceleration (vibration) signal is processed by a control circuit and amplifier. Then it feeds the electromagnetic actuator, which amplifies the signal. As a result of such a feedback system, a considerably stronger suppression of vibrations is achieved compared to ordinary damping.

[edit] Subframe isolation

Subframe vibration isolation graph: force transmission on suspended body vs. frequency for rigidly and compliantly mounted subframes.

Another technique used to increase isolation is to use an isolated subframe. This splits the system with an additional mass/spring/damper system. This doubles the high frequency attenuation rolloff, at the cost of introducing additional low frequency modes which may cause the low frequency behaviour to deteriorate. This is commonly used in the rear suspensions of cars with Independent Rear Suspension (IRS), and in the front subframes of some cars. The graph (see illustration) shows the force into the body for a subframe that is rigidly bolted to the body compared with the red curve that shows a compliantly mounted subframe. Above 42 Hz the compliantly mounted subframe is superior, but below that frequency the bolted in subframe is better.