SU596848A1 - Vibration stand for testing objects at resonance frequencies - Google Patents

Description

(54) WEBRSS-GND FOR TESTING FREQUENCIES OF OBJECTS ON RESONANT

key integrator, filter and actuator reverser unit and a differentiating circuit connected in series to the output of the first driver, shaper pulse driver, AND element, the second input of which is connected to the output of the phase switch, and the second fig.1tp, the output of which is connected to the second input of the unit reverse. The invention is illustrated in the drawings, where in FIG. 1 shows a block diagram of a vibrostand for testing objects at resonant frequencies; in fig. 2 shows time diagrams of the output signals of elements during tests at an odd tone of the structure; in fig. 3 shows the time diagrams of the output signals of the elements when tested at an even tone of the structure.

The vibration table contains a master oscillator 1, a power amplifier i, a vibrator 3, an oscillator auto-tuning circuit, having a vibration measuring transducer 4 mounted on the tested product, a matching amplifier 5, a phase detector 6, an actuator electr-nt 7, controlling the frequency of the master oscillator 1, switch 8. Co.mutator 8 contains two square pulse drivers 9 and 10, phase switch P, integrator 12, two filters 13 and 14, a differentiating circuit 15, a forked 16 pulse pulses, element 17 "And and a reverse 18 block.

The generator 1 generates electrical signals of a predetermined frequency, which are amplified by the power amplifier 2 and, through the vibrator 3, excite oscillations of the object under test at one of the resonant frequencies of the object. From the vibro-sensing transducer 4 fixed on the object, through the matching amplifier 5, the signal is fed to the phase detector 6. The second signal to this detector is supplied from the master oscillator 1.

When the oscillation frequency of an object leaves the resonant one, the phase of the signal from the vibration transducer changes, which leads to the appearance of a phase mismatch signal at the input of the phase detector 6, and a signal of a certain polarity appears at its output, which enters the actuator 7.

The sign of the output signal of the phase detector 6 depends both on the direction of the change in the frequency of the test object on the resonant one and on the fact that the structure is excited at an even or odd tone.

With the phase principle of stabilizing the resonant mode of objects with multiresonant frequency response, the phase shift between the signals at the input of the phase detector is determined by the following relationship: (2n-1) L: / 2, (, 2, 3, ...), where n is the tone number . As can be seen from this ratio, when testing on odd toHax, the signal of vibration sensor 4 lags behind the signal of master oscillator 1 by jr / 2 (Fig. 2 a, b), when testing on even tones, it is ahead by 7G / 2 (Fig. Za, b). This leads to the fact that with identical changes of the resonance frequency at odd and even tones of the design, the sign of the output voltage of the phase detector at odd tone will be opposite to

the output direction when testing on an even tone, and hence the control signal to the ispacillator element, is the opposite when changing the tone of the structure, which excludes the possibility of tuning the resonant mode during software testing of objects with multiresonant frequency characteristics. Thus, during software tests of multiresonant objects, when switching from one tone to another, it is necessary to automatically change the direction of frequency processing by the actuating element 7.

This is achieved by introducing a switch 8, to the two inputs of which a signal of the master oscillator 1 is supplied and, through a matching amplifier 5, the signal of the vibration measuring transducer 4.

Sinusoidal signals converted

The rectangular formers 9 and 10 (Fig. 2 c, d and Fig. 3 c, d) are fed to the inputs of the phase switch 11.

At the output of the phase switch 11, the signal appears only in the coincidence intervals of the output pulses of the formers 9 and 10 (Fig. 2d and Rx)

The output of the phase switch 11 is converted by integrator 12; and filter 13 to the control voltage i. is supplied to the first

5 input block 18 of the reverse, made on the basis of the transistor reversal | 1st relay amplifier.

To the second input of block 18, the reverse, the control signal, 1eni, comes in coincidence in the ale. Figure 17 "And the output signal of the phase switch 11 and the signal, with (| yurmatized by the differential circuit 15 and the driver. 16. During resonant tests on an even tone of the design, the output signal of the driver 16 (Fig. 3)) does not coincide in time

5 with the output of the {g-phase phase key (Fig. Rear). Signal, l control - enters only the first input of the reverse unit 18 and the reversible relay amplifier of the reverse unit .18 is in the initial state.

With resonance tests on an odd

0 the tone of the design, the output signal of the driver 16 (Fig. 2 g) coincides in time with the output signal of the phase switch (Fig. 2e) and to the second input of the reverser unit through the filter 14 receives a control signal that translates the reversing relay amplifier 6jTO 18 of the reverse to another stable the state and the reverse unit 18 outputs to the actuator 7 a control signal that changes the polarity of the input signal of the actuator.

0 The presence of a switch allows software testing of objects on even and odd colors of the structure and automates the tuning of the resonant mode of objects with multiresonant frequency response, shortens the time for preparing and conducting vibration tests of full-scale structures and improves the reliability of test results.

Claims (2)

1. “Vibration technology. Workshop materials, Moscow, Moscow House of Scientific and Technical Propaganda, 1974, p. 169-174. 2. USSR author's certificate number 248306 Cl. G 01 M 7/00, 1969. Odd dance Thursday fnoK