SU1515112A1 - String accelerometer - Google Patents

Abstract

This invention relates to a measurement technique. For acceleration measurements, body 1 is attached to a test object. Strain gauges 2 and 3 are connected to the bridge metering circuit, which is balanced, with the help of the current leads 4 and 5, 6 and 7. Inertial masses 8 and 9 are attached to the strain struts. To measure the temperature, the current leads 4 and 6 are connected together, and the current leads 5 and 7 are connected to a temperature meter. The parameters of the strain gauge are selected in such a way that the output signal of the temperature meter 10 will not depend on the magnitude of the acceleration, but will be determined only by the temperature of the strain gauge. 1 il.

Description

listened to

1

31515112

The invention relates to a measurement technique, namely to a measurement of accelerations.

The aim of the invention is to improve the measurement accuracy by simultaneously measuring acceleration and temperature.

FIG. 1 shows an accelerometer circuit; Fig. 2 is a diagram of the deformation of the Q of a pentostrum in the presence of acceleration.

The string accelerometer consists of a body 1, the first 2 and second 3 of the ten-string length 1, and 1 and ohmic contacts to them 4 - 7. The inertial masses 8 and 9 are fixed to the strain-5 strings. - from contacts 4 and 6 in series, and current leads from contacts 5 20 and 7 are connected to temperature meter 10. To measure the acceleration, the strain gauge is included in a pavement measuring circuit. Strain gauges are made of filament-like crystals 25 (PC) silicon, having one type of conductivity, for example, hole,

String accelerometer works as follows.

For measurements, the housing 1 is fixed 30 on the test piece. Strain gauges 2 and 3 are connected to the pavement measuring circuit, which is balanced, with the help of the current leads D and 5, 6 and 7. When stretched, the resistance of the strain, c string 2 increases, and the strain strain string 3 decreases. As a result, the imbalance of the bridge circuit occurs. The amplitude of the output signal is proportional to the magnitude of the acceleration. 0 71 l of temperature measurement of the current outputs 4 and 6 are connected together, and the current leads 5 and 7 are connected to the temperature meter 10. If the lengths of tensor strings 1, and Ij are the specific soprotinpe NIN p and j3., The coefficients of the stress sensitivity K. and K, the cross-sectional area, and I, as well as the Young’s moduli K, and E, and the seismic masses are chosen that at the same acceleration the change in resistance 1 (3R, the strain gauges and the resistance change / 5R strains 3,

50

LA, 4 R2

(one)

then the output temperature gauge 10 will not depend on the magnitude of the acceleration (strain of the strain gages), but will be determined only by the temperature of the strain gauges. The total resistance of the strain gauge in the amount, taking into account (1), will not depend on the deformation

R + R 2 P-.

(2)

Tenzostruna 3 under the action of load 9 is experiencing a deformation of the bend. Suppose that the thickness of the strain gauge 3 is equal to b (figure 2). The curvature of the bend of the sides of the strut will be g and g, and

g, + h.

(3)

The values of the radii of curvature will depend on the acceleration with which it moves - the object under study. The deformations of sides 11 and 12 of the strain gauge 3 (Fig. 2) will be respectively determined by the formulas:

 2; (compression) (4)

  -, (stretching) 2 2 2 (.

The resulting deformation of the entire string will be

one

one

,,. ev (--i --- i)

(6)

Since r: r, + b, the total strain of the strain gauge will be a compressive strain. For a strain gauge with perforated conductivity, the resistance R decreases with compression, while the strain gauge 2, which is stretched, increases the resistance. To fulfill conditions (1) and (2) it is necessary that

3R, - / 3R, Oh,

(7)

Suppose that divider 1 is moving with acceleration a, while strain gauges 2 and 3 (.Fig.1) are affected

forces:

F 2 mg (g + a); F 3 m u (e a),

(eight)

where g is the acceleration of free fall.

The relative deformation of the strain gauge in this case is determined by the relations:

B

i niiiS-l-Si E S 2

e, L- msls-i-il,

(9)

E

S,

5 - 3

de 3, a;

S.SjjEjjE, is the cross-sectional area and Young's moduli of the strut 2 and 3;

L is a coefficient depending on the geometric shape of the ten-string 3.

The resistance of the strain gauge when deformed varies according to the dependencies:

uR | -.-cjf r-i

(ten)

 K - coefficients tenso. sensitivity of strain gauges 2 and 3, have specific resistivity; resistance of strain gauges without deformation is, respectively:

RI f2- l./Sj)

R, RZ-H / ZZ

(eleven)

Taking into account relations (9), (10), (11), relation (1) can be written as

K o - - “ls-i-s)

Pas E, R2

 K P i T); - p with

s / s h 3

(12)

after conversion we get

151

51 12

n) J L Si- -li-5i-- 2, / 13)

sh, k ,. , C., 3

If strain gaps 2 and 3 are made of one NC, then I, f f, i E g Ej and relation (13) will take

view

0

5} J mg

Cg-1,

(i)

The stress-response coefficient Kj is the effective stress-response coefficient of strain-gauge 3 and depends on the initial length l,

5 mob b.

When conditions (13) or (1-4) are fulfilled by a string accelerometer of this design, it is possible to simultaneously measure the parameters of the oscillating bodies and

0 ambient temperature.

Claims (1)

Invention Formula A string accelerometer containing a body, on which a strain gauge in the form of a filamentary single crystal semiconductor with current leads at the ends is fixed at one end, and a seismic Q mass at the other end, characterized in that, in order to improve the accuracy of measurements, it is perpendicular to the first A strain gauge is connected to the body by two ends of a second semiconductor strain gauge, which has the same type of conductivity with the first string, in the center of which the second seismic mass is suspended, and both strand grids are included in ost and sequentially connected to the meter tem0 perature.