SU721678A1 - Method and device for determining two components of mechanical oscillations of a structure - Google Patents

Description

A rum connected to the recorder, the inputs of a logic multiplier are connected to the outputs of a two-phase oscillator, and the output is connected to the control input of a synchronous detector.

FIG. 1 is a block diagram of an apparatus for carrying out the method; in fig. 2 — graphs of the forms of electrical voltages at various points in the device circuit.

A device for determining two components of mechanical oscillations of structures comprises a two-phase master oscillator 1, an amplifier 2, a filter 3, a recorder 4, an energizer 5, a strain gauge 6, a logic multiplier 7, an additional filter 8 and a synchronous detector 9, and the structure 10 under study.

Energizer 5 is connected to the generator 1, and the transducer 6 is installed on the structure under study, its input. Through the amplifier 2 is connected to one of the outputs of the two-phase master oscillator 1, and the output through the filter 3 with the registrar 4. The synchronous detector 9 is connected between the outlet of the strain gauge 6 and the additional filter8 connected to the recorder 4. The inputs of the logic multiplier 7 are connected to the outputs of the two-phase master oscillator 1, and the output to the control input of the synchronous detector 9.

The method is carried out as follows.

The exciter 5 excites mechanical oscillations of the structure 10 with the frequency of the master oscillator. These oscillations are converted into electrical voltage by a strain gauge b fed from generator 1 through amplifier 2. In FIG. Figure 2 shows the voltage curve at one of the outputs of the generator 1 and at the output of the amplifier 2, which is shifted by an angle relative to the voltage of the second output of the generator 1, curve c. The strain adjuster 6 will see the oscillations of the studied point of the structure 10, which are expressed by the change in time of the relative deformation, curve c. The output voltage, curve -g, with strain gauge b, smoothed file3, is measured by the recorder 4. This voltage carries information about one of the KOMHOBHT mechanical vibrations of the krng operation 10. When the strain gauges are switched on in a bridge circuit with two active arms, it is:

Ucp e v cosH-f

where g

Q - amplitude of relative deformation of strain gauges

S is the coefficient of sensitivity of the strain gages of the EUT — the amplitude of the supply voltage;

f is the phase shift relative to the excitation signal of the structure.

At the same time, the output voltage of the strain gauge 6 is supplied to a synchronous detector 9, which is used to simultaneously detect this voltage, through each hour of the period. The average value at the output of the synchronous detector 9 is equal to

, l-h

To control the synchronous detector 9, a logical multiplier 7 serves. At the output of the multiplier 7,

0 square-wave square-wave pulses, the duration and pause of which is equal to a quarter of the voltage period of the two-phase master oscillator 1, curve d in FIG. 2. Voltage, curve e,

5 at the output of the synchronous detector 9 carries information about the second component of the mechanical vibrations of the structure. It is measured by the recorder 4 after being filtered by an additional filter 8.

The invention will reduce the measurement time of the component by half, which leads to a reduction in the development time of objects in mechanical engineering.

Claims (2)

1. A method for determining the two components of mechanical oscillations of structures, concluding that the structure is excited by a harmonic signal from the master oscillator, converts-oscillations into electrical voltage by a strain gauge and measures the constant component of the output voltage of the strain gauge, according to which the value of one of the components of mechanical oscillations of structures, characterized in that, in order to reduce the measurement time, synchronous detection of the output voltage of the strain gaps is carried out a transformer through a quarter of the period of the signal from the master oscillator and measure the constant component of the voltage obtained, according to which the value of the other component of the mechanical vibrations of the structures is judged. 2. An apparatus for carrying out the method of claim 1, comprising a two-phase driving oscillator, an amplifier, a filter, a recorder, an exciter connected to a generator, and mounted on the structure under study strain gauge, the input of which is connected through an amplifier to one of the two-phase master oscillator outputs, and the output through a filter with a recorder, characterized in that it is equipped with a logic multiplier, an additional filter and a synchronous detector connected to the output of the strain gauge and an additional filter connected to the recorder, the inputs of the logic multiplier are connected to the outputs of the two-phase master oscillator, and the output is connected to the control input of the synchronous detector. Sources of information are taken into account in the examination 1. Smyslov V.I. Experimental methods for studying aircraft oscillations. M., Works of TsAGI, vol. 1217, 1970, p. 30 (prototype). er-g,. (.J3) / -