SU1425480A1 - Magnetoanisotropic mechanical stress meter - Google Patents

Abstract

The invention relates to load measuring technology and allows to expand the range of measurable forces and to improve accuracy by eliminating the influence of the gap. Two mutually perpendicular magnetic conductors 2 and 3 of the meter are installed with a gap on the object under study. The signal from measuring winding 5 through rectifier 15 and differential amplifier 16 is fed to the first input of subtractor 11. Rectifier 6 and differential amplifier 7 are connected to the circuit of excitation winding 4. Signal from amplifier 7 through first adjustable amplifier 8, first bias circuit 9 and divider 10 is supplied to the second input of the Bitch reader 11. In addition, the same signal through the second adjustable amplifier 12 and the second bias circuit 13 is fed to the first input of the multiplier 14, to the second input of which a signal is applied. with subtractor 11. A signal from the multiplier output, proportional to the measured value, is fed to the input of the measuring device 17. 1 sludge. i (L

Description

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The invention relates to a high-performance technique and can be used to measure mechanical stresses and anisotropy of structures and parts made of ferromagnetic materials.

The purpose of the invention is to expand the measurement range and improve accuracy by eliminating the influence of the gap.

The drawing shows a structural diagram of the meter.

The meter contains a magnetoanisotropic transducer 1 mounted with a gap b on the test surface with two mutually perpendicular U-shaped magnetoproducts 2 and 3, on which are located the excitation winding 4 and the measuring winding 5, respectively. A rectifier 6 is connected to the excitation winding power supply circuit connected to the output of the differential amplifier 7. The output of the amplifier 7 through serially connected first adjustable amplifier 8, the first bias circuit 9 and divider 10 is connected to the second input of the subtractor 11 and through the serially connected second variable amplifier 12 and the bias circuit 13 - to the first input of multiplier 14, to the second input of which is connected to the output of the subtracter 11. The measuring coil 5 via a series-connected rectifier 15 and differential amplifier 16 is connected to a first input of the subtractor. The output of the multiplier 14 is connected to the measuring device 17.

The meter works as follows.

The magnetoanisotropic transducer I is installed with a gap on the test surface. An alternating voltage is applied to the field winding 4. A current i flows through the field winding.

The magnitude of the nominal gap & is chosen sufficiently large from the condition that the excitation current is independent of the measured mechanical stresses 6. When energized to the excitation winding circuit in the measuring winding 5, an electromotive force is induced, which determines the zero signal Uo. When a mechanical stress in the measuring winding is applied to the structure under study, the useful signal Us is added to the zero signal Uo, the value of which is proportional to the stress o in the elastic region.

During the operation of the structure under study, for example, of the ship’s shaft, due to the beating, vibration and g., The gap bn oscillates with an amplitude Ab. At the same time, the output voltage of the measuring winding U "varies according to the law (Ao-f WoAb) + W / (Ab + WbLb), the excitation current according to the law i bfC b, where A, B, C are constant coefficients depending from the characteristics of the converter. After straightening in block 15, the measuring winding voltage Un, simmet

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More distinctly relative to the common point of the circuit, is fed to the input of the differential amplifier 16, and at its output an unbalanced voltage (A "+ BoA6) -i-Uf / (Ae + BtМ) is obtained, which is fed to the first input of the subtractor 11. the input of the subtractor from the output of the divider 10 serves as a voltage U Uo / A), such that, and. At the output of the subtractor, there remains a voltage proportional to the second term of the measuring winding voltage UH Ue / (As Ab). This voltage is applied to the second input of the multiplier 14, the first input of which from the output of the bias circuit 13 receives the voltage and A - | - B Ab such that A "g A, Bf B.

As a result of the multiplication operation from the output of the multiplier 14, an electrical voltage U is supplied to the measuring device 7, which depends on the measured voltages 0 and does not depend on the fluctuations of the gap Ab. The voltages U and U are formed in the channel of the excitation winding 4. At the output of the rectifier 6, connected to the excitation winding supply circuit, a constant voltage U is obtained, proportional to the excitation current i:

and UH + Sv6.

This voltage in the differential amplifier 7 is converted from a symmetrical form to a non-symmetrical one with respect to a common point. Then this voltage U, carrying information about the gap, the passage channel containing the first adjustable amplifier 8, the first circuit 9 and the divider 10, adjusted when the meter is tuned, is converted at the output of divider 10 to the voltage U, compensating the zero signal and its change from Influence of the gap. And the passage through the channel containing the second adjustable amplifier 12 and the second bias circuit 13, also adjusted during tuning, the voltage U at the output of the circuit 13 is converted into voltage and eliminating the influence of the gap fluctuations on the useful signal Us.

Thus, in the meter, changes in the output signal of the transducer caused by the oscillations of the gap are eliminated with the help of electrical signals that are also dependent on the fluctuations of the gap, but not dependent on the applied mechanical stresses. These signals are generated by isolating a constant voltage proportional to the excitation current, depending on the changes in the gap.

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Claims (1)

Invention Formula A magnetoanisotropic mechanical stress meter containing two mutually perpendicular U-shaped magnet lines, one of which has an excitation winding and the other measuring winding, rectifier and measuring device, characterized in that in order to expand the measurement range and improve accuracy, it introduced two differential amplifiers, two adjustable amplifiers, two bias circuits, divider, subtractor, multiplier, and the rectifiers are included in the circuit of the excitation winding and the measuring winding, the rectifier outputs are connected to the differential power amplifiers, the output of one of which connected to the first input of the subtractor, and the output of the other through a serially connected first adjustable amplifier, the first bias circuit and a divider connected to the second input of the subtractor and through a serially connected second adjustable amplifier and second bias circuit to the first input of the multiplier, the second input of which is connected to the output of the subtractor and the output - with the measuring device.