RU1790704C - Method for vibration isolation - Google Patents

Abstract

Usage: mechanical engineering, vibration technology, namely vibration isolation of various objects. SUMMARY OF THE INVENTION: an elastic beam with a load is fixed with its ends on a vibroactive object, the low form of bending vibrations of the beam with a load is determined, and it is articulated with two nodal points on the vibration-protected object. Dependences of the location of nodal points on the place of securing the cargo on the beam are presented. 1 ill.

Description

The invention relates to vibration technology, mainly to methods for attaching vibroactive objects to provide vibration isolation.

A known method of fastening a vibrating machine containing active and reactive masses connected with the base and with each other through elastic elements, in which the elastic elements rest on the base at the points of minimum vibrations 1.

However, when these points oscillate, vibration is transmitted to the base, in addition, the attachment of the vibrational points of the elastic elements to the flexible base changes the vibration forms of the elastic elements, and therefore the vibration isolation efficiency and vibration amplitude of the vibrating machine depend on the flexibility of the base.

Closest to the technical nature of the proposed is a method of vibration isolation, which are determined

the forms of its free vibrations, taking into account the concentrated masses, the coordinates of the nodal points, after which these points are in contact with the fixed supports 2.

The disadvantages of the method are that the nodal points of the oscillations may be absent, since their presence is determined by the ratio of the stiffness and inertial properties. In addition, the forced waveforms, and hence the i-coordinates of possible nodal points, are determined not only by the forms of free vibrations, but also by the parameters of the periodic external influence, therefore, such coordinates can be found by free forms only approximately. The coordinates of the nodal points determined for the forms of free vibrations do not coincide with the coordinates of the nodal points of forced vibrations after the vibroactive object is supported on a supple base, therefore, the efficiency of the vibration

about

l with

lation with this method depends on the compliance of the base.

The aim of the invention is to increase the efficiency of vibration isolation. An increase in the effectiveness of vibration isolation is expressed in the fact that independence of the effectiveness of vibration isolation and the vibration amplitudes of the vibroactive object from the flexible ™ base is achieved.

The proposed C eIV is achieved by the fact that in the claimed method of vibration isolation, an elastic beam with a load installed on it is fixed with its ends on a vibroactive object, the lowest form of bending vibrations of the beam with a load is determined, and it is articulated with two nodal points on a vibroprotected object on distance x about. l ft from the corresponding end of the beam with the load to the nodal point located between the end of the beam and the load, and the weight mass m is determined from the relations:

o3 - (3 K I + K2 + 2 2) a + l} Ej + 2K2l 0.tag

/ Z3 --- | (3I K + 2 +2 K2) / 3-) EJ + 2l2K 0

m ag K

.3 E J k + l

m --- -t, -,

(ktfar

where K, I is the distance from the ends of the beam to the load,

E J - bending stiffness of the beam,

 a) - the given vibration frequency of the vibroactive object.

The drawing shows a diagram of vibration isolation of a vibroactive object 1 by means of a load 2 mounted on. elastic beam 3, from the vibration-protected object - the base - 4,

The proposed vibration isolation method is implemented as follows for a vibroactive object oscillating at a frequency of 531 rad / s. With a bending stiffness of the beam, 764 H m2, the distance from the ends of the beam to the load, 225 m of

m

0

5

0

5

0

5

0

5

the ratio that ensures the existence of a nodal point between the end of the beam and the load,

3 E J (K + I) 3 26.664 (0.225 + 0.225)

(k I) 2 ar (0.225 0.225) 2 (100.531) 2 1.41 kg,

we choose the value of the mass of the load kg. The distance a and / 3 from the corresponding end of the beam with the load to the nodal point is determined from the relations

ar --Јqrr (3KI + K2 + 2l2) (K + 1) E | + 2k2 | 0) ta / h

/ Z9-t- (3 I K +12 + 2 K2) Ј-6Jl + J lEl + 2 | 2K 0, tag K

in the particular case when we get a / -y, therefore we have the expression

2 .. 12 EJ, - 9.

d y + 2 yes O

m or

Substituting the values for this case, we obtain

/ -0.151875 y + 0.00689 0.

Having solved the obtained cubic equation, we determine the distance from the corresponding end of the beam with the load to the nodal point of the car at 0.046 m.

The use of the claimed method of vibration isolation improves the efficiency of vibration isolation. Efficiency of vibration isolation is ensured by changing the compliance parameters of the base, which increases the life of the base structures and eliminates the harmful effects of vibration on people and devices associated with the base. The independence of the vibration amplitudes of the vibroactive object from the flexibility of the base allows us to obtain the invariability of the operating modes of the vibroactive object when it is installed on substrates with different values of compliance and when the flexibility of the base changes during operation.

Claims (1)

SUMMARY OF THE INVENTION A method of vibration isolation, in which an elastic beam with a load installed on it is fixed with its ends on a vibrating-reactive object, the lowest form of bending vibrations of the beam with a load is determined and articulated with two nodal points on the vibration-protected object. characterized in that, in order to increase the efficiency of vibration isolation, the distance a and / 3 from the corresponding end of the beam with the load to the nodal point located between the end of the beam and the load, and the weight mass m are determined from the relations: (3 K I + K2 + 2I2) 26 (Kt bj + 2K2l 0. mar | / 33 (3 KI + l2 +2 K2) 6 (K9 +) EJ + 2I2K 0.tag K m 3 E J k + (kl) 2o / where K is the distance from the ends of the beam to the load; E J - bending stiffness of the beam; w - the given vibration frequency of the vibroactive object.