SU581387A1 - Device for determining amplitude-frequency characteristics - Google Patents

Description

The invention relates to vibrometry.

Devices are known for determining the amplitude-frequency characteristics of objects when tested for vibration, in which the amplitude-frequency characteristic is recorded using a two-coordinate recorder mechanically associated with a generator.

Such devices have a constant recording scale along the frequency axis, since the scanning of a two-coordinate oscillator chart paper is carried out as a result of the mechanical connection of the master oscillator and the recorder, therefore a detailed reading; resonance peaks of a high frequency response of objects is often difficult 1.,:

The most close to P1 is the unit; the known device is known for this device for which the amplitude-frequency characteristics are determined; : Generally Connected Generator of Excitation with Frequency Scanning Control Unit and Connected to the Zyhod | This unit sets the lower and upper limits of the frequency sweep range, automatic controller

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excitation level, which ensures the constancy of a given vibration parameter, a power amplifier, a vibration exciter, a vibration level meter and a two-coordinate recorder connected to it by one of the inputs, as well as an analog-frequency converter that converts the frequency of the generator to a voltage proportional to it 2.

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In this device, the m-scale of recording along the frequency axis can be changed by changing the gain in the unwinding circuit of the given axis of the two-coordinate perH Tpatopa. In cases where research often the MI range is significantly already in the; Sega scan range of the clock G1E and zishiv & generator and

O lies in .tsn "in vr. G. Record of investigate01: b, / part of the range.) At a given part of the paper requires a number of manual operations associated with the installation, the end of the recording is started and

5 selection of the corresponding record scale. These operations are necessary when any change in the studied frequency range is possible; however, they increase the time required to prepare the SpArpaTopa for measurement and recording. thereby reducing productivity 4: ore operator. The goal of the first invention is to increase the operator's productivity by automating the process of setting the beginning and end of the sequence and selecting the appropriate recording scale for the range of exploratory frequencies to record at a given section of chart paper. This is achieved by the fact that the proposed device additionally includes the first and second adders, the dividing unit, the y.riocation unit and the recording field setter, and the outputs of the lower and upper limits of the frequency sweep range are connected to the inputs of the first adder and connected to the input of the block, to the second input of which the recording field setter is connected, the output of the division unit is connected to the input of the multiplication unit, the second input of which is connected to the output of the second adder, whose inputs are connected; respectively, to the output of the setpoint of the lower limit and the output of the frequency-analogue converter, and the output of the multiplication unit is connected to the input of the two-coordinate recorder, the active frequency scan of the recording unit. The drawing is a block diagram of the described device. It consists of an excitation generator 1, including an own generator 2 and a frequency sweep control unit 3 of the automatic regulator 4 of the excitation amplitude with a feedback circuit, which includes the amplifier 5 and the measuring vibrator 6; power amplifier 7; 8 vibrations exciter; gauge of 9 level & radium installed on the subject about &10; measuring amplifier 11, analyzer 12, two coordinate recorder 13, frequency converter 14 is analogous to setters of lower 15 and upper 16 limits of the frequency sweep range of adders 17 and 18, division unit 19 of multiplication unit 20 and unit for recording field 21. The excitation signal generated by the generator 2 and И31 "@ m frequency rate with a frequency set in a frequency sweep set by frequency sweep unit 3 in a frequency range specified by units 15 and 16, excites an exciter 8 exciter with power amplifier 7, the excitation level of which is kept constant throughout frequency range by an automatic controller 4 using a feedback circuit consisting of amplifier 5 and a measuring vibration transducer 6. Thus, the exciter 8 acts on the object 10 by harmonic oscillations with constant nnym varying parameter at a predetermined speed and in a predetermined frequency range. The level of oscillations of the test object 10 is determined by the meter 9, the signal of which is fed through the measuring amplifier 11 and the analyzer 12 to the vertical sweep amplifier of the two-coordinate recorder 13. The difference in the voltages U & f of the adjusters 15 and 16, determined by the cytwaTopOM 18, is proportional to the range of the studied frequencies and is Llfj is the voltage proportional to the upper limit of the range of studied frequencies, Uj is the voltage proportional to the lower limit of the range of studied frequencies. This voltage is applied to a 16de / shade unit, to the second input of which a voltage is applied to the setter 21 of the recording floor, which is proportional to the required recording length on the chart paper. At the output of the division block, the voltage is obtained ... Hl The one that is multiplied in the multiplication unit 20 with the voltage is taken 1 from the adder 17, the value of which is equal to the difference of the voltage proportional to the current frequency U | and voltages Uf, entering the inputs of this sumiator. Thus, at the output of block 20, there will be a voltage equal to U - f i. I b «-t Voltage Tsuu is fed to the horizontal input of a two-coordinate recorder /. It can be seen from formula (1) that, given UfK U | e and l / t, the sweep of recording along the frequency axis will always start at the position v corresponding to zero voltage at the input of the horizontal sweep amplifier of the two-coordinate recorder (Ujs Uut and Ua «x O) and the sweep length will correspond to the preset (S- and "and Ubtat" Ub) When using the assumed device, tuning the rewuithrator along the frequency axis is reduced to setting the lower and upper frequency calibrated in units of frequency limits of the 2-frequency probe and the length setting records (scale) recording field recording, which significantly reduces the time it takes for the recorder to prepare for measurement and recording, and also allows for more detailed analysis of narrow-band portions of the object's own resonances.