SU606120A1 - Vibration testing apparatus - Google Patents

Description

one

The invention relates to the technique of mechanical tests and can be used for testing objects in harmonics. chesky vibration.

Vibration test devices are known in which stabilization of a given vibration parameter is carried out on a feedback circuit acting on an amplifier with a controlled transmission coefficient, connected in series with a power amplifier,

In such devices, the amplified signal removed from the vibration measuring transducer is rectified and compared with the setpoint adjuster. In the case of the difference of the rectified voltage from the voltage of the driver, the difference of these voltages affects the amplifier with a controlled transmission coefficient, changing its gain and the magnitude of the excitation signal at the input of the amplifier

power in such a way as to reduce this difference to zero.

The control gain amplifier is a low-inertia link, so the control voltage

must not contain pulsations, otherwise the excitation signal will be modulated by the pulsating voltage, which will lead to an increase in the coefficient: nonlinear distortion of the reproduced signal. To eliminate pulsations, the rectifier filter should have a longer time constant, S-10 times the maximum oscillation period of the vibrator.

On the other hand, the time constant of the rectifier filter determines the adjustment speed, which increases with increasing filter time constant. With a long time constant, the control circuits do not have time to react to an abrupt change in the level of vibration due to the resonant properties of both the tested structure and the vibrator, as a result of which the accuracy of setting the level of vibration is reduced.

The closest to the technical nature of this invention is a device for vibration testing, containing; serially connected master oscillator, a booster with a controllable transmission coefficient, urinary bridges, a vibrator, a vibration-measuring transducer, and a feedback circuit connected to the control input of the bodies with a controlled transmission coefficient and made in the form of successively connected amplifiers and; In this device, an active input detector is used as the straightening of the bodies and the filter, the time constant of which is equal to 2–4 periods of vibrations of the vibrator. Correspondingly, the speed of the control is higher, too, and, consequently, the accuracy of the tests. Such a speed of adjustment satisfies most types of tests for harmonic vibrations. However, when tested at low often those (10 Hz and below), the adjustment speed remains very high. The aim of the invention is to improve the accuracy of testing aa by increasing the speed of regulation in the low-frequency region. The aim is to ensure that the feedback circuit is made in the form of serially connected block for extremal values, a switching element and a storage unit. The drawing shows a functional diagram of the device. The device for vibration tests contains a sequentially connected oscillator 1 with a voltage divider 2, an amplifier 3 with a controlled transmission coefficient, a power amplifier 4, a vibrator 5, a vibration measuring converter 6 with a voltage divider 7 at the output, and a feedback circuit including series-connected The extremum block 8 of extrinsic values commute the shy element 9 of the memory block Y. The device works as follows. From divider 2, the excitation voltage is applied. through the amplifier 3 with a controlled gain on power amplifier 4 and a vibrator 5. The vibrations generated by the amp and tamper, the level of which is determined by the voltage level at the input of the pod 4, is taken by vibrating head 6 7 enters an extremal extraction unit 8; values. The selected ampere 8 values of this voltage through the switching element 9 are fed to the transmission bactus 10 acting on equipment 3. The block 8 for extracting extreme values allocates the amplitude value of each half-cycle of sinusoidal with 1 signal of both polarities. During a time many times shorter than the time of one half-period of oscillation, the switching element connects to block 8 the storage unit 1O, which fixes this amplitude value until the next connection of block 8 to block, i.e., for the time of one half-period. At the same time, the gain of the amplifier 3 is also fixed. The use of stepwise regulation, i.e., regulation, in which the right voltage changes from one value to another stepwise and retains its value within one half period, allows a significant increase in speed adjusting without noticeably increasing the non-linear distortion coefficient of the reproduced vibration. This increase in speed is especially significant in the low frequency range, where the oscillation period is longer to duration. Formula and 3 Brea This is due to the fact that, in order to increase the accuracy of testing for / by increasing the speed of adjustment in the low-frequency region, the feedback circuit is made in the form of serially connected blocks selection of extreme values, the switching element and the storage unit. Sources of information taken into account in the examination; 1, Cherepov V.F., et al. Equipment for automatic control of electrodynamic vibratory installations. L., LDTP, 1872, p. 8. 2. B {yole and Kjерr. Control generator type 1025. Technical data, 1973, October.