Vibration control can be divided into 5 categories according to the means of restraining vibration:
(1) Damping: to eliminate or reduce the vibration source, cure the method, but at present technically, there is no mature technology can effectively eliminate the vibration source.
(2) Vibration isolation: eliminate or weaken the vibration transmission. A subsystem (vibration isolator) is added between the vibration source and the controlled object to reduce the influence of the controlled object on vibration excitation.
In accordance with the way of transmission, vibration isolation is divided into:
a. Active Vibration Isolation: Isolate the vibrating machine (vibration source) from the foundation with a vibration isolator to prevent or reduce the dynamic pressure transmitted to the foundation, thereby suppressing the impact of the vibration source on the surrounding equipment. Isolation vibration source.
b. Negative vibration isolation: the need to protect the machine with the vibration isolator vibration foundation (vibration source) isolated to prevent or reduce the impact of foundation vibration on the machine. Isolate the response.
Note: Although the concept of active vibration isolation and negative vibration isolation are different, the implementation method is the same. All the devices that need to be isolated are installed on a timely vibration isolator (elastic device) so that most of the vibration is absorbed by the vibration isolator absorb.
(3) Vibration Absorption (Dynamic Vibration Absorption): A subsystem (dynamic vibration absorber) is attached to the controlled object to generate the vibration absorption force to reduce the influence of the controlled object on vibration excitation.
(4) Resonance (Damping): A damper or damping element is attached to the controlled object to reduce the response by consuming energy.
(5) Structural Modification: By modifying the dynamic characteristic parameters of the controlled object to make it vibrate to meet the predetermined requirements without any additional subsystems
Isolation is the use of vibration between the components of the impedance mismatch, to reduce the vibration transmission measures. Vibration isolation technology is often used in the vicinity of the vibration source, the vibration energy is limited to the vibration source, not to the outside world, so as not to stimulate the vibration of other components; also used in the need to protect objects near the need to low vibration objects with the vibration environment Open, to avoid the impact of objects by the vibration. Vibration isolation measures taken to design the appropriate vibration isolator. The principle of vibration isolation is to design the natural frequency of the object and the vibration isolator (mainly the spring) system to be much lower (at least 3 times lower) than the excitation frequency; however, it is necessary to pay attention to the design of the characteristic impedance of the vibration isolator The characteristic impedance of the connected components varies greatly (at least 3 times worse). To this end, vibration isolators, such as wire springs, but also pad rubber, blankets and other cushions. In the design of the isolator, damping should also be considered. On the process of starting the speed of the machinery, vibration isolators should be added damping measures to avoid vibration through the resonant frequency is too large.
Damping is a measure of dissipating vibration energy into heat by viscous or frictional effects. Damping can restrain the vibration of the vibrating object and reduce the vibration amplitude of the vibrating object in the resonance frequency region. The specific measures are to increase the damping of the component or to lay the damping material and the damping structure on the component. For example, the damping alloy material developed in recent years has great internal damping and large enough rigidity to be used for manufacturing low-noise mechanical products. In addition, the vibration source mounted dynamic absorbers, for some vibration source is also effective measures to reduce vibration. On the impact of vibration, vibration absorption measures can effectively reduce the shock excitation caused by the vibration response. Electronic vibration absorber is another type of vibration absorption equipment. Its vibration absorption principle is different from the above vibration isolation and damping. It uses the electronic equipment to generate a vibration with the same amplitude and opposite phase as the original vibration amplitude to offset the original vibration to reduce the vibration (see active noise reduction).
The relationship between vibration isolation and damping Under normal circumstances, the vibration isolation equipment and damping equipment function is similar, the two are mutually reinforcing, so in the selection of time, we must choose a reasonable balance.
In some strong vibration environment, the use of a number of vibration protection measures can also eliminate or reduce the hazard of human vibration.
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