RU10260U1 - BEND MEASUREMENT DEVICE - Google Patents

Abstract

A device for measuring deflection, consisting of a base plate and a sensitive element, which is a steel plate of equal resistance with strain gauges glued to it on both sides, a holder mounted on the base plate, a steel grade rigidly fixed in the controlled area of the object under study, a DC amplifier and recorder, characterized in that it is additionally equipped with a subtractor, and the inputs of the subtractor are connected to strain gauges, and the output to a DC amplifier.

Description

Deflection measuring device

The invention relates to the field of laboratory studies of the mechanical properties of samples and materials of building constructions and can be used in testing laboratories and in enterprises of building industry.

A known sensor for measuring deflection when tested for low-cycle fatigue by a pure bend / Kornblum A.I. et al. A sensor for automatic measurement of the deflection of flat samples in studies of low-cycle fatigue by pure bending // Factory Laboratory. 1976.- No. 2.- P.235 /, including a plate in which a sensitive element is installed in the form of a steel plate with strain gauge transducers glued on it from both sides.

The sensor consists of a base plate, in the lower part of which basic probes are installed, and in the upper part there is a sensitive element, which is a steel plate of equal resistance with strain gauges glued to it from both sides. Between the base probes there is a measuring probe connected by a lever to the element. The sensor plate is mounted on the platform of the test installation, and the sensor during the test makes a reciprocating motion. The deflection of the sample is determined by the movement of the probe relative to the probes that are constantly in contact with the sample. The movement of the probe causes deformation of the sensing element, which, in turn, is transformed by the strain gauge circuit into an electrical signal fed to the strain gauge and the oscilloscope.

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constantly experiencing variable deformations, which leads to fatigue of both the resistors themselves and the glue line when testing a series of samples. As a result of this, the resistance of the strain gauge changes and is not a stable value during the measurement process. The influence of these factors affects the accuracy of the final results, since the fatigue characteristics of the sensor are integrated over time. In addition, when measuring, there is a subjectivity factor, which is due to the use of an oscilloscope as a recording unit of measurements. The oscilloscope has a certain delay time of the information signal from the input signal, which is essential for minor changes in deformations in the controlled product.

It is known that a device for measuring deflection / Application No. 93026256/33. Device for measuring deflection / V.V. Bredikhin, S.V. Povetkin. - Publ. 1996, Bull. No. 5 (prototype) / including a base plate and a sensitive element, which is a steel plate of equal resistance with strain gauges glued on it from two sides, as well as a holder mounted on the base plate, and a steel mark rigidly fixed in the controlled area of the studied object and intended for periodic contact with a sensitive element. In this case, the sensing element is cantilevered on the holder with the possibility of reciprocating movement in the horizontal plane and subsequent periodic fixation in the working position. Strain gages through a DC amplifier connected to a multi-point recorder.

A disadvantage of the known device is the low accuracy of the measurements. it

It is explained by the fact that the signals from the transistors are recorded separately on the multi-point recorder. According to the records of these signals, the magnitude of the deflection of the structure is judged by comparing the curves during the reading of the measurement results, that is, there is a subjectivity factor that increases with slight changes in deformations in the controlled product (the shape of the curves become indistinguishable).

the basis of the invention is the task of improving the accuracy of measurement in small and multi-cycle tests.

The technical result obtained as a result of solving the problem lies in the fact that the device for measuring deflection, consisting of a base plate and a sensitive element, representing it as a steel plate of equal resistance with glued on

two sides of it with tensistors, a holder mounted on a base plate, a steel grade rigidly fixed in the controlled area of the object under study, a DC amplifier and a recorder, is additionally equipped with a subtractor, and the input of the subtractor is connected to

shadow resistors, and the output with a DC amplifier. So on

The recorder records the amplified differential signal from the teneistors.

The result is improved measurement accuracy.

In FIG. 1 shows a schematic diagram of the proposed device.

The device includes a base plate 1 and a sensing element 2,

I represent; it is a steel plate of equal resistance with glued on it on both sides by tensors 3, and also the holder 4,

mounted on the base plate 1 and steel grade 5, rigidly fixed in the controlled area of the test object 6 and designed for periodic contact with the sensing element 2. In this case, the sensing element 2 is cantilevered on the holder 4 with the possibility of reciprocating movement in the horizontal plane and subsequent; fixation in working position. Tenzhstory 3 through the subtractor 10 and the DC amplifier 11 are connected to the recorder 12.

The device operates as follows; in their image. The sensor plate 1 is mounted on a fixed frame 7, near the test structure 6, while the sensitive element 2, which is a steel elastic cantilever beam of equal resistance, must be placed „,,

to

lean on the same horizontal line with mark 5, rigidly taped on the dropable structure 6. Prior to the measurement, the sensitive element 2 should have an initial deflection in the direction of movement of the structure. When exposed to an external cyclic load, the building structure 6 together with the brand 5 will receive a variable deflection. If it is necessary to take the readout, the sensitive element 2 is moved horizontally with a micrometer screw 8 until it comes into contact with the mark 5. In this case, the deformation of the sensitive element 2 is converted by the subtractor 10 into the difference of the ten signals: Y1Stor 3 and is amplified by a DC amplifier 11 into the electrical signal recorded by the recorder 12. After taking the count, the sensing element 2 is removed from contact with the brand 4.

The use of the proposed device in comparison with the prototype when testing for low and high cycle fatigue by bending provides improved control accuracy when measuring deflection.

Claims (1)

A device for measuring deflection, consisting of a base plate and a sensitive element, which is a steel plate of equal resistance with strain gauges glued to it on both sides, a holder mounted on the base plate, a steel grade rigidly fixed in the controlled area of the object under study, a DC amplifier and recorder, characterized in that it is additionally equipped with a subtractor, and the inputs of the subtractor are connected to the strain gauges, and the output to the DC amplifier.