SU896456A1 - Device for excitation of tested samples self-induced oscillations - Google Patents

Description

one

The invention relates to testing equipment, namely, devices for driving self-oscillations of samples.

A device for exciting self-oscillations of samples is known, comprising a power amplifier, a vibration exciter, a vibration sensor mounted on the sample, a phase shifter and a band-pass filter whose output is connected to the input of the power amplifier til.

This device allows only one sample to be tested in a self-oscillating mode at a time, which is a drawback of the device if it is necessary to test batches of samples of small dimensions and weight.

Closest to the technical CSWHOCTH invention is a device for driving self-oscillations of test samples containing a series-connected harmonic signal generator, the input of which is connected to a mode switch, power amplifier and oscillator, a feedback circuit including a vibration sensor mounted on the sample, a phase rotation and an amplitude detector, as well as a set of filters, a frequency-dependent switch connected to the output of a harmonic signal generator, and a key that controls the input Which is connected to the output of the mode switch, and the output - to the control input of the power amplifier 2. The known device allows

fO initiate self-oscillations with only one frequency and test one sample. In practice, vibration tests of samples of low weight and size are often carried out.

The tS, which allows several test samples to be simultaneously placed on the platform of a vibration exciter. Testing such samples sequentially with the aid of a known device results in unproductive losses of energy and test time, which is a drawback of the device.

The purpose of the invention is to increase test performance by simultaneously testing several samples.

This goal is achieved so that the device is equipped with a sugmator,

30 1connected blocks

matching, prohibiting, delays, the output of which is connected to the control input of the prohibition block, and an indicator, a matching unit whose outputs are connected to the output of the block, and a switching unit, the feedback circuit is made multi-channel by the number of test samples, the inputs of the switching unit connected to the outputs of the phase shifters, the frequency dependent switch and the coincidence unit, and the outputs to the inputs of filters whose outputs are connected through an adder to the key input, the outputs of the amplitude detectors are connected to the second inputs b shackles matching, matching and indicator.

The drawing shows the block diagram of the device.

The device contains series-connected harmonic signal generator 1, power amplifier 2, exciter 3 exciter, a multichannel feedback circuit including vibration sensors 4 mounted on test samples 5, phase shifters b and amplitude detectors 7, whose outputs are connected to the input of matching unit 8, sequentially connected block 9 prohibition, block 10 delay, the output of which is connected to the control input of block 9, prohibition, and indicator 11. The outputs of the amplitude detectors 7 are connected to the inputs of the indicator 1 1 and block. 12 matches, to the other inputs of which the output of block 9 is connected. The outputs of the coincidence unit 12 are connected to the inputs of the switching unit 13, to which the outputs of phase shifters b and the frequency-dependent switch 14 are also connected, the outputs of the switching unit 1 are connected to the inputs of the filter set 15, the outputs of which are connected to the power amplifier 2 through the input 16 , to the control input of the key 17 and the generator 1 are connected the outputs of the switch 18 modes. The device works as follows.

In the mode of searching for resonant frequencies, the signal of the generator 1 through the amplifier 2 of the power excites oscillations of the exciter 3 oscillations and test samples of variable frequency. At the same time, the output signal of generator 1 is fed to a frequency dependent switch 14 for connecting filters from the set 15 to the feedback circuit, in the passbands of which are the resonant frequencies of the test samples. The switching frequencies of the frequency dependent switch 14 correspond to the cutoff frequencies of the filters from set 15. The signal at the first output of the frequency dependent switch 14 is present until

as long as the frequency of the oscillator 1 is in the passband of the first filter from the set 15.

The signals of the vibration sensors 4 through the phasers 6 are fed to the inputs. amplitude detectors 7, which generate pulses indicating re-onances of the test samples 5. These pulses through the block 12 matches are fed to the inputs of the block

Q 13 switching together with the output signals of the frequency-dependent switch 14. Under the influence of these signals, switching unit 13 connects to the feedback circuit for

 each test sample 5 filters

 from set 15, in the passbands of which are the resonant frequencies of the tested samples 5.

After detecting the first resonance, the following condition is satisfied:

0 regular and mylc from the outputs of the amplitude detectors 7 are fed to the input of the switching unit 13 only after the end of the inhibit pulse generated by the delay unit 10,

5 included by the falling edge of pulses from the outputs of amplitude detectors 7.

The impulse of the delay unit 10 is applied to the control input of the unit 9 behind the Q preta. In this case, the pulses from the output of the matching unit 8 through the prohibition block 9 do not arrive at the secondary inputs of the matching unit 12 and, as a result, the pulses from the amplitude detectors 7

 do not pass to the inputs of the switching unit 13.

The duration of the inhibiting pulse must be such that at a given rate of change in the frequency of the generator 1, it corresponds to

0 change the generator frequency by the bandwidth of the filter from the set 15.

For the resonant frequencies in the specified zone, the feedback is

5 is not closed and it is noted on display unit 11 which samples 5 cannot be tested together. This is necessary to exclude such things as grabbing or frequency suppression, which leads to a distortion of the test mode.

After the end of the search mode (if there are incompatible patterns, they are excluded from the test process), using the switch 18 modes, the device is switched to the self-oscillation mode. The generator 1 and the frequency dependent switch 14 are turned off, and the key 17 is closed. In closed circuits

0 communications for each of the test specimens 5 are excited by self-oscillations. At the output of the adder 16, the signal has a complex shape, however, due to the resonant properties of the tested samples 5 and when the components are separated

along the frequency axis, the oscillations of each of samples 5 are in the form of a sinusoid.

Testing multiple samples mounted on the oscillator platform accelerates the testing process and reduces energy costs.

Claims (2)

1. USSR author's certificate number 386303, cl. G 01 M 7/00, 1973. 2. USSR author's certificate of 5 on application 2512963 / 25-28, : CL G 01 M 7/00, 1979 (prototype). Oo-d to ug  (i i SH.Y :: W. Laiyj Ui : “$