SU815547A1 - Random-vibration testing machine - Google Patents

Description

(54) DEVICE FOR TESTING ON RANDOM VIBRAS

I

The invention relates to vibration tests of nanometers of articles, namely, devices for testing for random vibrations, and can be applied in instrument-making & SRI.

A device for testing for random vibrations, a series-connected noise generator, forming filters, automatic level control amplifiers (AGC), an adder, a shaker, a spectrum analyzer, an amplifier control unit, is known.

The disadvantage of this device is low accuracy, due to limited signaling.

The closest to the proposed technical entity is a random vibration test device containing a series-connected noise generator, forming a filter {L, amplify AGC, adder, shaker, spectrum analyzer, dispersion analyzers, AARz amplifiers control unit.

A disadvantage of the known device is the limitation of the dynamic range, which causes the limitation of the signal, which distorts the generated spectrum.

The purpose of the invention is to improve accuracy.

The goal is achieved by

o that the devices are snected by a second control unit and two three-channel 1C blocks on which the first is connected by an input to a noise generator, and an output is connected to the inputs of the shaping filters,

S and the second input - to the output of the adder, and the output to the input of the shaker, each three-channel block contains its adder and in each (channel controlled attenuator, the output of which is connected to the input / accumulator, FLtr with equal falling characteristic and a filter with a uniformly increasing x-ray band, the 3 opposite filters are switched off to the channels of the three-channel blocks at the input of attenuators of the same name, the inputs of the three dispersion meters are connected to the inputs of the second three-channel block attenuator, and the outputs to the input of the second control block The outputs of which are connected to the control inputs of all attenuators. The drawing shows a block diagram of the proposed device.The device for testing random vibrations contains a noise generator 1, an amplifier 2 matching the output of the generator 1 with the input of the first three-channel unit 3 consisting of controlled attenuators 4-6, adder 7 and filters 8 and 9 with uniformly decreasing and uniformly increasing characteristics, respectively, the output of the first three channel block 3 is connected to the input of shaping filters 1O, amplifiers 11 AGC, adder 12, the second three-channel block 1 3, consisting of controlled attenuators 14-16, adder 17 and filters 18 and 19 with uniformly increasing and uniformly decreasing characteristics and responsibly, the output of block 13 is connected to the input of the vibrating table 20, the output shaker through the analyzer 21, the AGC amplifier control unit 22 is connected to the amplifier 11, dispersion meters 23-25 connected by inputs to the inputs of controlled attenuators 14-16, and outputs to the second attenuator control unit 26, 4, 5, 6, 14, 15 and 16. The device works as follows. m The signal of the noise generator through the amplifier 2, the first three-channel unit 3 is fed to the input of the forming filters 1O. The generated signal through the AGC amplifiers 11, the adder 12, the second three-channel block 13 enters the shaker 20. The signal removed from the shaker through the analyzer 21, the AGC amplifier control unit 22 adjusts the gain factors of the 11 AGC amplifiers. The signals from the outputs of the dispersion meters 23–25 go to the second control block 26, the outputs of which are connected to the attenuator control inputs 4,5,6,14,15 and 16. In the absence of a signal at the attenuator control inputs, the latter have some fixed average transmission coefficients . The second control unit 26 and the three-channel blocks 3 and 1 3 operate in such a way as to stabilize the dispersion of the signal at the output of the antenna near the threshold value, while not allowing for signal limiting, which eliminates the distortion generated by the spectrum, thereby increasing the accuracy of testing. If the signal at the attenuator control inputs is present, and the dispersions at the outputs of filters 18 and 19 are equal, then block 26 reacts only to the signal of dispersion meter 23, which measures the total dispersion of the signal at block 13, and controls attenuators 4 and 14, leaving the coefficients the transmission attenuators 5, 6, 15 and 16 are unchanged. If the dispersion at the input of unit 13 exceeds its threshold limitation, the transmission coefficient of the attenuator 4 decreases, and the attenuator 14 increases as many times as the attenuator 4 decreases. vault dispersion IU at the entrance of block 13 to the desired threshold value. Increasing the gain of the attenuator 14 increases the variance at the output of the adder 17, which broadens the dynamic range of the formation and reduces the distortion caused by the limitation of the signal. If the dispersion at the input of block 13 is not equal to the required one, and the dispersion at the outputs of filters 18 and 19 are not equal, for example, the dispersion at the output of filter 18 is larger than at the output of filter 19, then the transmission coefficients of attenuators 4 and 14 are changed, and attenuators 5 and 15 decrease until the dispersion at the output of the filter 18 reaches its threshold value. Learning that the amplitude-frequency characteristic (AFC) of the attenuator 5 is evenly decreasing, and the a. Attenuator 15 is uniformly increasing, their product is equal to a certain value, independent of frequency, i.e. the resulting frequency response is uniform, therefore, a newly reduced reduction in the transmission coefficients of attenuators 5 and 15 does not change the shape of the resulting frequency response. A decrease in the attenuator transfer ratio 5 causes a decrease in the total dispersion at the input of block 13, which results in an increase in the transmission coefficient of the attenuator 4 and a corresponding decrease in the transfer coefficient of the attenuator 14. In turn, an increase in the total dispersion at the input of block 13 causes the dispersion threshold value to be exceeded at the filter output IS what's up

even a reduction in the transmission coefficients of attenuators 5 and 15, etc., as long as the dispersions at the input of block 13 and at the output of filter 15 do not become equal to their threshold values. 13 is equal to the threshold value, the dispersion at the output of the filter 18 turns out to be less than the threshold value, then the transmission coefficients of the attenuators 5 and 15 increase until the dispersion at the output of the filter 18 reaches its threshold value. This entails exceeding the total dispersion of the threshold value at the input of block 13, which causes a corresponding change in the transmission ratio of attenuators 4 and 14, etc., until the dispersion values at the input of block 13 and the output of filter 18 reach their threshold values.

If the dispersion at the output of the filter 18 is less than the dispersion at the output of the filter 19, then the transmission coefficients of attenuators 5 and 15 have constant mean values, while the transmission coefficients of attenuators 4, 14, b and 16 are controlled by a similar algorithm.

Claims (2)

1. USSR author's certificate No. 419755, cl. Q 01 M 7 / 1OQ 1974. 2. Vibration testing elements and automation devices. M., Sergi, 1976, p. 100.