SU1383125A1 - Device for testing objects for vibration - Google Patents

Abstract

The invention relates to vibration testing of objects for broadband random vibration. The purpose of the invention is to increase the accuracy of vibration reproduction. The device contains a white noise generator 1, multichannel driver 2, usi-. power indicator 5, shaker 6, spectrum analyzer 7, stabilization unit 10, unit 19 for calculating real and imaginary values of frequency characteristics, and a matrix unit 24, 3 Cp f-ly, 2 ill.

Description

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The invention relates to the field of testing objects for the effects of broadband random vibrations and can be used when testing objects of instrumentation and mechanical engineering for the effects of wideband random vibrations.

The purpose of the invention is. increasing the accuracy of reproduction of broadband random vibration with a given spectral density during testing.

Figure 1 presents the block diagram of the device; figure 2 - block diagram of the matrix block.

The device contains a white noise generator 1., A multichannel driver 2, consisting of n parallel-connected filters 3 and adder 4; an amplifier 5; a shaker 6 with an object; an analyzer 7 of the spectral power density of a random signal; each of the parallel-connected channels consists of series-connected a narrow-band filter and a dispersion meter of stabilization circuits 8, each of which consists of a setpoint 9 of a positive, close to zero value, a setpoint 10 of the given spectral values comparator II, dividing devices 12, keys 13 and 14, multipliers 15 and delay lines 16, a key 17 and a reference voltage generator 18 common to stabilization circuits, a unit 19 for calculating the real and imaginary values of the frequency characteristics of a multichannel imager, This consists of n channels, each of which consists of a square root extraction unit 20, a multiplication device 21 and a setting unit 22 values of the frequency-phase characteristic of the former, a setting unit 23 of the coefficients of the biortonormed function system and a matrix block 24 (FIG. 2) consisting of multipliers and accumulators 26, the first inputs of multiplication devices 25 are connected to the corresponding outputs of the setter 23, the second inputs of multiplication devices 25 are connected to the corresponding outputs of block 19, and the outputs of devices 25 the multiplications are connected to the corresponding inputs of adders 26 whose outputs are connected to the outputs of the matrix block 24.

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The device works as follows.

At the moment of switching on the device, the potential is released, which opens the key 17 only for a time from the passage of the signal through the closed-loop playback system. The constant voltage of the unit level of the generator 18 of the reference voltage through the switch 17 is fed to the inputs of the lines 15 delays of all the stabilization circuits and to the inputs of the block 19 for calculating the real and imaginary parts of the frequency characteristics of the multichannel generator. In block 19, the signals arrive at the inputs of the square root extraction devices 20, from the outputs of which the signals are fed to the first inputs of the multipliers 21. The predetermined values of the phase-frequency characteristic of the driver are supplied to the second inputs of these devices from the setting unit 22. The output signals of the multipliers 21 are fed to the matrix unit 24, to which the pre-calculated coefficients of the biortonormed function system are also supplied from the setting unit 23. In block 19, the values of the frequency response of the driver at the points CO, COj are calculated. n frequency range. The signals from the output of block 19 arrive at the corresponding inputs of the matrix block, in which the parameters determining the gain and phase relations in each channel filter are calculated. The signals from the output of the block 24 are fed to the controlled inputs of the driver 2.

The white noise generator 1 delivers a random signal with a unit spectral density to the inputs of filters 3, the signals from the outputs of which are added by the adder 4. In the random signal obtained at the output of the former 2, the spectral density at the points с,,, C0j, ..., o) ri is equal to unit, since the values of the spectral density Sn (co) of the output signal of the former 2 at the points,, cOj, ..., (On are equal to the values coming from the circuits of the 8 st line to the inputs of block 19.

Thus, at the initial time, the values of the spectral density of the output signal of driver 2, as well as the input signals of block 19, are equal to one, and at any other time, these values are equal to the values of output signals of stabilization circuits 8.

Then the signal from the output of the imaging unit 2 goes to the power amplifier 5 and then to the shaker table 6 with the object. A random signal from a sensor (not shown) enters the spectral density analyzer 7, the outputs of which determine the values of the spectral density SrCWit + O of the current vibration at points sa (,,, ..., from and are supplied to the stabilization circuit 8.

In each stabilization circuit 8, the value S (co, t + C) of the corresponding 15 output of the analyzer 7 is fed to a comparator 11, where it is compared with a close to zero value that comes to the second input of the comparator 11 from the sensor 9, and to the first input of the device 20 va 12 dividing, where dividing a given value of the spectral density Sj (co), coming from setpoint 10 to the second input of dividing device 12, by value is made. 25 Comparing S ((o, t + t) with b comparator 11 is performed so that when setting S (CC1k) 0 to exclude division in dividing device 12 by an amount close to zero, since with this also .5- (03 t + T) 0.

If S (co, t + t) e, then the comparator 11 generates a signal locking the key 13 and opening the key 15. Then in the device 14 multiplying the prescheduled value of the spectral density 5 |, (SOC, t) of the output signal of the imager, which is fed to the second input of this device from the delay line 16, is multiplied by a single 40 signal of the reference voltage generator 18, which through the key 15 is fed to the first input of the multiplication device 14. Then the output signal of the circuit in stabilization and the value of the spectral 45 density Sy | (cD, t + c) of the signal of generator 2 are equal to the delayed (the previous value of 5 "(o ,, t), thereby maintaining the value of the parameters of the driver, SrCWot + CQ + t) 6 E. It is assumed that StCWw.t) O only if S (o) 0.

If S (to, (, t), then the comparator 11 generates a signal that locks key 15 and the open key 13 .. In this case, the signal from the device output 12 is equal to SjCco) /

(S) enters via key 13 to the first input of multiplier 14, where it is multiplied by a delay line 16 signal equal to the previous spectral density value S (cO, t) of the driver signal.

From the output of the multiplier 14, the signal determining the value S (t) of the signal at the output of the imaging device enters the input of the delay line 16, the output of the stabilization circuit 8 and the corresponding input of the block 19.

Stabilization circuits 8 determine the spectral density S (co, t + f) of the output signal of shaper 2, taking into account information about the dynamic characteristics of the vibrating stand 6 with the object, which is contained in S. (co, t + t).

Thus, during the tests, the device maintains the specified values of the spectral density of the current vibration, regardless of the change in the dynamic characteristics of the shaker with the object by introducing feedback in the form of stabilization circuits to adjust the gain factors and phase ratios of the shaper filters. At the same time, hardware reproducibility is eliminated, since the shape of the frequency response and the mutual influence of the filters of the driver are learned.

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The present invention improves the accuracy of reproduction of random vibration during the test with the non-stationary dynamic characteristics of the shaker from objects, providing adjustment of the parameters of the driver.

Claims (4)

1. A device for vibration testing of objects, containing in series a white noise generator and a multichannel driver, an amplifier, a shaker with a test object and a sensor, and a matrix unit, the first input of which is connected to the output of the first preset, characterized in that, in order to increase accuracy Vibration playback, additionally, a voltage reference generator, serially connected spectrum analyzer, stabilization unit and real and imaginary value calculation unit are often added GOVERNMENTAL characteristics output coupled to the second input uppoy c-matrix block, the output of which is connected to respective inputs of a controlled multi-channel shaper, .a output reference voltage generator is connected to the second input and via the third input key to stabilize the unit. 2. The device according to claim 1, wherein the multichannel driver has n tunable filters, the inputs of which are combined and are the input of the driver, and the outputs are connected to the input of the adder, the output of which is the output of the former, the control inputs of the tunable filters are the controlled inputs of the former. 3. The device according to n.l, which means that the stabilization unit contains n channels, each of. which consists of a delay line of serially connected master, comparator and multiplier, serially connected spectral density generator, divider, first and second keys, the second input the first key is connected to the comparator output, and the output is connected to the multiplier output, the second input of the second key is connected to the output of the delay line, and the output is to the first input of the delay line and is the output of the stabilization unit, the second input of the multiplication unit is the second input of the stabilization unit, and its first input is the second input of the comparator connected to the second input of the divider, and the third input is the second input of the delay line. 4. The device according to claim 1, wherein the unit for calculating the real and imaginary values of the frequency characteristics contains n channels, each of which consists of a unit for extracting the square root, the output of which is connected to the first inputs the first and second multiplication blocks, the second inputs of which are connected to the corresponding codes of the setpoint generator of the frequency-phase characteristics, and the outputs are the outputs of the calculator of the real and imaginary values of the frequency characteristics, and its inputs are the inputs of no square root. f-otgs Om13 Fig.d