SU1401316A1 - Regulated resonator for vibration-testing machine - Google Patents

Abstract

This invention relates to a technique for vibration testing of articles. The purpose of the invention is to increase the reliability of test results by eliminating the distortion of the sinusoidal waveform during adjustment. The adjustable resonator is made in the form of a beam 1 with longitudinal holes located symmetrically with respect to the plane of symmetry of the beam, coinciding with the plane of bending. The longitudinal holes are installed with the possibility of rotation of the plate 4. The rotation of the plate adjusts the resonant frequency by changing the flexural rigidity of the beam. The plates 4 are fixed to the tin 5, inserted into the notches of the 6 plates. 1 hp f-ly, 2 ill.

Description

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This invention relates to a technique for vibration testing of products, namely, resonators with adjustable resonant frequency.

The purpose of the invention is to increase the reliability of test results by eliminating the distortion of the sinusoidal waveform during adjustment.

FIG. 1 shows an adjustable resonator, a general view; in fig. 2 - the same, side view.

Adjustable resonator contains beam 1 with slot 2 and longitudinal holes 3 located symmetrically with respect to the plane of symmetry of the beam coinciding with the plane of bending, plates 4 for frequency adjustment, installed in holes 3 of beam 1 with the possibility of rotation, wedge 5 inserted into notches 6 plates 4, holes 7 for the elements of fastening the resonator to the table of the vibrostand (not shown).

The resonator, divided by a transverse slit 2 into two parts, has a cross section of the upper part with sides in the form of a semicircle, and the bottom in the form of a rectangle.

The thickness of the lower part of the resonator is calculated so that its own resonant frequency exceeds the maximum frequency of the working part to eliminate the effect on the oscillations of the resonator.

The plates 4 are in contact with the resonator along the arc of the circumference of the apertures 3 and must be sufficiently rigid to avoid deformation. To eliminate the transverse oscillations of the resonator, the number of holes must be even (i.e., two or more). The stiffness of the plates is provided by the choice of the material from which they are made, with the highest modulus of elasticity (compared with the material of the resonator).

The resonator is adjusted as follows.

The resonator is placed on the shaker table and secured. Plate 4 is fixed using wedges 5 at the desired angle to the horizontal axis. It is known from oscillation theory that the resonant frequency of oscillation of a system depends on the flexural rigidity of the beam E I and is determined by the formula

where L is the root of the frequency equation, the type of which depends on the method of fixing the beam;

E-modulus of elasticity of the material of the beam; 1 is the moment of inertia of its cross section; E is the span length; t-mass beams.

By varying the moments of inertia within certain limits, a change in the resonant frequency is achieved. The minimum moment of inertia of the plates is in their horizontal position, the maximum is in the vertical position. 5 A wedge 5 is inserted into the notches 6 in the plates 4. A test article (not shown) is mounted on the resonator. The vibration effect produced by the vibration test bench excites resonant bending vibrations of the upper part of the resonator, as a result of which the test product mounted on the resonator is affected by an increased level of vibration.

The use of the proposed adjustable-frequency resonator makes it possible to test various types of products having different resonant frequencies. When the resonator frequency changes, the mode of oscillation remains unchanged, in contrast to the known adjustable resonators with elements movable along the beam.

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Claims (2)

1. Adjustable resonator to vibrostand control, containing a beam and installation-movable elements to adjust the flexural rigidity of the beam, and means of fixing these elements, characterized in that, in order to increase the sinusoidal waveform during adjustment, the beam is made symmetrically with respect to the plane of symmetry of the beam coinciding with the plane of bending, and the adjustment elements are made in the form of plates mounted in the holes of the beam with the possibility of rotation. 2. A resonator according to Claim 1, characterized in that the ends of the plates are made with notches, and the means of fixing the plates are wedges inserted into the notches.