SU1059452A1 - Bending moment measuring method - Google Patents

Abstract

A METHOD .-. MEASUREMENT OF A BENDING MOMENT OF A BAR, consisting in measuring the distance between the first point of a measuring section and tangent to an elastic line at the second point of this area, determining the scaling coefficient of coupling of a bending moment with a linear distance, characterized in that In order to improve accuracy and simplify the measurement process, the linear distance between the second point of the measuring section and the tangent to the elastic line at the first point of this section of the beam is additionally determined, and the bending moment t is determined by multiplying the scale factor by the sum of the measured linear distances. sd with

Description

The invention relates to instrumentation, namely to the technique of measuring loads on the power elements of the structure of various devices. It is intended to measure bending moments arising in parts of machines, for example, in shafts.

The known method of measuring bending moments, consisting in measuring the bending deformation of a beam on the longitudinal measuring C section: angles of rotation and relative transverse movement of the ends of the beam in the coordinate system rigidly connected to the longitudinal axis of the non-deformed beam, is calculated by bending. moments l.

The disadvantage of this method is the low measurement accuracy due to its complexity, since it requires registration of three parameters: two rotation angles and one linear displacement.

Closest to the present invention is a method for measuring a bending moment of a bar, consisting in measuring the distance between the first point of the measuring section and the tangent to the elastic line at the second point of this section, determining the scaling coefficient of the coupling of the bending moment with a linear distance of 2J.

However, this method is not accurate enough and is complicated, since it requires the determination of two scale factors, as well as the definition of linear and angular displacement.

The purpose of the invention is to improve the accuracy and simplify the measurement process.

This goal is achieved by the fact that, according to the method of measuring the bending moment of the beam, consisting in measuring the distance between the first point of the measuring section and the tangent to the elastic line at the second point of this area, determining the scaling coefficient of the connection of the bending curve with a linear distance the distance between the second point of the measuring section and the tangent to the elastic line at the first point of this section of the beam, and the bending MOMeH-fi is determined by multiplying the scale factor the sum of the measured linear distances.

FIG. 1 shows a diagram of the elastic line of the beam with the measuring section; in fig. 2 - cantilever beam, loaded at the end of the transverse load or torque; in fig. 3 is a side view of a bar with distance meters; in fig. 4 view from above on the timber; in fig. 5 view along the beam.

In the drawings, elastic lines 1 of the bar are marked, tangent 2 to elastic line 1 at point A, tangent 3 to elastic line 1 at point b of bar 4, supports 5 and b, flexible connections 7, teeth 8 of supports 5 and 6, flexible jumpers 9 , point stops 10, rods 11 and 12, force P applied to the beam at a distance L from point b, bending moment M, measurement base, distance 2 between the calculated embedment of the beam and the cross section for application of external force factors, distance 6 from points R to tangent 2 and distance Sj from point L to tangent 3.

A device that implements. The proposed method contains two gauges located on the sides of the beam. Each gauge contains on the side surface of the beam 4 supports 5 and b, oriented along the neutral plane of the beam 4 at points A and B at the ends of the longitudinal measuring section of length a. The supports 5 and b are attached to the beam 4 by flexible ties 7. Each support 5 and b is made in the form of a rigid two-prong fork With spiked teeth 8, which, in order to give it stability by plastic springs - flexible jumpers 9, are connected to point stops 10 with rounded blunt The tops of the support 5 and b with teeth 8 is equivalent to the knife support. Rod 11 is rigidly attached to the support 5 in the direction of the support b, and the rod 12 is rigidly attached to the support b in the direction of the support 5. 7 The device also contains optical distance meters between the support 5 and the rod 12, not shown in the drawings. support b and barbell 11.

Before measurement, the scale factor K is determined experimentally or by calculation.

Experimentally, the scale factor K is determined by the following set of operations: load Bru 4 with a known tare load by a transverse force P at a distance L not less than the height of the beam from the second support b and measure the distances .6 and between the rods 11 and 12 and the supports 5 and 6, calculate the scale factor using the formula

TO

64, + 6,

where Mdv is P (L + a / g). If in the unloaded condition of the bar there are non-zero distances 540 and between the rods 11 and 12 and supports 5 and b, then the scale factor is calculated by the formula

M

Ae

TO

5.-t, 0-520 Restrictions on the minimum distance L are imposed in accordance with the principle of Saint-Venant. By calculation, the scaling coefficient is determined by the formula: | b The measurement by the proposed method is performed as follows: when loading a bar with an unknown load to be measured, a linear distance 8 between the first rod 11 and the second support 6 (between point B on the elastic line 1 and tangent 2 to the elastic line 1 at point A) and 8 between the second rod 12 and the first support 5 (between point D on the elastic line 1 and tangent 3 to the elastic line 1 at point b) normal m to the rods 11 and 12 ( normal m to tangents 2 and 3). According to the results of distance measurements, -b, and calculate the bending moment MDb on the average between the supports in the beam cross section according to the formula LB 1 1 If in the unloaded state of the beam there are non-zero distances and between the bars. 11 and 12 and supports 5 and 6, the bending moment is calculated using the formula KB, + KSj - K6.0 - kV. The proposed method allows to measure the bending moment with greater accuracy while simplifying the measurement process as a whole.

7h

S /

F1 / HL

5L

FIG. five

Claims (1)

METHODS OF BENDING TORQUE OF a beam, concluding. in measuring the distance between the first point of the measuring section and the punitive to the elastic line at the second point of this section, determining the scale coefficient of the connection between the bending moment and the linear distance, characterized in that, in order to increase the accuracy and simplify the measurement process, the linear distance is additionally determined between the second point of the measuring section and the tangent to the elastic line at the first point of this section of the beam, and the bending moment is determined by multiplying the scale factor by the amount measured linear distances.