SU1464051A1 - String-type transducer of mechanical strain - Google Patents

Abstract

This invention relates to measurement; technology and can be used for strain gauging of objects subjected to various types of loading. The aim of the invention is to expand functional capabilities. The goal is achieved by the fact that the oscillation divider is made with a through groove and is provided with a clamp to pinch the string sensing element passed through the groove, while the oscillator divider is offset relative to the line passing through the supports, with which the sensitive element is placed on the substrate the separator of vibrations is also fixed, the sensitive element is equipped with a system of excitation and pickup of oscillations included in the electronic measuring unit, at the output of which signals are formed, which is proportional to national shear and tensile deformations applied to the substrate. 2 Il. % i (L

Description

one

The invention relates to a measuring technique and can be used for strain gauging of objects subjected to various types of external loading.

The aim of the invention is the distribution of functionality.

Figure 1 shows the converter; figure 2 - block diagram of the Converter.

The string converter of mechanical stresses (Fig. 1) contains the substrate 1 with the extreme supports 2 installed on it and the oscillation separator 3. One of the extreme supports is provided with a string tension adjustment unit, which is

 the threaded pair of the adjusting nut of the adjusting screw 5. The string sensing element 6 is rigidly fixed on the adjusting nut and

other end to the opposite extreme support. In this case, the middle part of the string, which is located in the through groove of the oscillation separator, is clamped by means of a fixing screw 7.

 Thus, string resonators are sections of a string enclosed between supports and an oscillation separator.

An apparatus for measuring mechanical stresses (Fig. 2) includes the proposed mechanical stress transducer, pathogens 8 and

cl

1464051

Receivers 9 electromagnetic oscillations, electronic measuring unit 10,

The electronic measuring unit provides the excitation of resonant vibrations of string sensing elements, the selection of electrical signals with frequencies f | and f ,, vibrations of the string sections and measurement of the frequency of the electrical signals f and f. The jITo frequencies f, and f judge the values applied to the object of measurement of the loads.

The converter works. in the following way.

The fixing screw 7 is retracted (Fig. 1 and thus releases the string control element from being clamped in the oscillation separator. When the adjusting screw 5 is rotated, the frequency f sections of the string, concluded between the supports and the oscillation separator. Having achieved the necessary tension of the string, the corresponding frequency, which oscillated the strings

one

compression, then the natural frequencies of oscillations of the sections of the string f and f in the presence of both force actions can be expressed by equalities

ft

f. -dfr -df,

ten

0

fo + dfc,

(one)

in equalities (1), the sign - before the value of ufp corresponds to the action of compressing 1x force. In the event of a tensile force, replace it with.

Obviously) that the frequency f,, is equal to

f -1

liili

 2

 f about - f p

(2)

differs from the initial resonance frequency of oscillations of the sections of the string fjj by the value of sfp, depending only on the value of the tensile-compressive force applied to the object.

On the other hand, the frequency f / is equal to

H.

The resonators f clamp the string in the {oscillation separator with the help of a fixing screw 7.

The work of a transducer mounted on an object subjected to I-tensile deformations and compression and simultaneously to shear deformations is that the action of tensile-compressive forces applied to the strain-gauge object and directed along the line connecting the base of the extreme supports of the transducer, leads to a decrease in voltage in both sections of the string. This causes a decrease in the frequency of their own oscillations. The effect of the forces causing shear deformation. And directed perpendicularly to the line connecting the bases of the extreme supports of the converter, leads to a change in stresses in both parts of the string with a different sign. The natural frequency of oscillation of one section of the string increases, the other decreases. If dfc denotes the change in the eigenfrequency of oscillations of the section of the string under the action of shear forces, and Afp indicate in (2 the change in the natural frequency of oscillations of the section of the string under the action of

 2

 L

with

(3)

is determined only by the magnitude of the shear forces acting on the strain gauge object.

By using the transducer and measuring the magnitude of the frequencies f, and fi, it is possible to simultaneously judge the magnitudes of the forces causing deformations of the contraction and shear in the measurement object.

Claims (1)

Invention Formula A string mechanical voltage transducer containing a string sensing element attached through supports to the substrate and an oscillation divider, characterized in that, in order to expand its functionality, the oscillation separator is provided with a through groove and a clamp to pinch the string sensing element passed through the groove when This oscillation separator is offset relative to the axis passing through the supports, and is fixed to the substrate. 1 Yu ft 1