RU199215U1 - Electromagnetic sensor for measuring internal stresses in a ferromagnetic rod element of a building structure - Google Patents

Abstract

The utility model relates to the field of measuring instruments, namely to instruments for continuous monitoring of ferromagnetic bar elements of building structures under the influence of tensile-compression forces. The technical result is an increase in the reliability of the sensor design due to the absence of detachable and movable elements, as well as ensuring a continuous monitoring process at high reliability due to the stationary installation of the sensor on the investigated rod element and taking into account the temperature at each measurement of the magnitude of internal stresses in the rod element. The electromagnetic sensor for measuring internal stresses in the ferromagnetic rod element of the building structure includes an internal sensor frame for placing the rod element with a temperature sensor built into it, two located one under the other, isolated from each other, primary and secondary concentric windings, fixed over the frame, and the outer shell of the sensor, while D1 = D2 + 2 x l, D2 = D + 2xL, where D is the diameter of the bar element, D1 is the diameter of the primary winding, D2 is the diameter of the secondary winding, L is the wall thickness of the inner frame of the sensor, l is the thickness of the secondary winding, 4 ill.

Description

The utility model relates to the field of measuring instruments, namely, instruments for continuous monitoring of ferromagnetic bar elements of building structures under the influence of tensile-compression forces.

Known electromagnetic sensors designed to determine mechanical stresses using a magnetic circuit for magnetizing a product (RU 2195636, publ. 27.12.2002, RU 2189020, publ. 09.10.2002, RU 2441227, publ. 27.01.2012, RU 2527310, publ. 27.08. 2014, RU 2527666, publ. 10.09.2014, CN 102235924, publ. 09.11.2011, CN 101246143, publ. 20.08.2008).

The work of known sensors is based on the relationship of mechanical stresses in a ferromagnetic material with magnetic properties, which manifests itself in the form of the Villari effect (Physical encyclopedia). They are used in cases of periodic checks for defects, which does not allow high-precision continuous monitoring of the stress-strain state of building structures such as cable-stayed and hanging systems, stress and conventional reinforcement of reinforced concrete structures, load-bearing cables for drawbridges and lifting mechanisms.

There is also known a magnetic sensor for measuring internal stresses of ferromagnetic materials, which is built into portable measuring instruments for measuring the stresses of components of loaded products (CN 102539027, publ. 04.07.2012).

The sensor is made with two freely opening and closing coils, isolated from each other. Metal wire harnesses are parallel and insulated from each other. One end of each wire harness is connected to a plug and the other end to a corresponding terminal on the socket. The sensor is mounted on the investigated product, measurements are taken, and then dismantled.

The disadvantage of the known sensor is that it cannot be used to continuously monitor ferromagnetic rod elements under the action of tensile-compressive forces used in structures such as cable-stayed and hanging systems, tensioned and conventional reinforcement of reinforced concrete structures, supporting cables for drawbridges and lifting mechanisms, since the sensor is removable and its movable / detachable parts are subject to increased wear. In addition, since such a sensor must be dismantled, it is impossible to use it for laying in reinforced concrete structures during concreting.

No close analogs were found.

The technical result is to increase the reliability of the sensor design due to the absence of detachable and movable elements, as well as to ensure a continuous monitoring process with high reliability due to the stationary installation of the sensor on the investigated rod element.

The technical result is achieved by the fact that an electromagnetic sensor for measuring internal stresses in a rod ferromagnetic element of a building structure includes an inner frame of the sensor for placing a rod element, two located one under the other, isolated from each other, primary and secondary concentric windings fixed over the frame, and the outer sheath of the sensor, while

D1 = D2 + 2 x l, D2 = D + 2xL, where

D - diameter of the bar element,

D1 - diameter of the primary winding,

D2 - diameter of the secondary winding,

L is the wall thickness of the inner frame of the sensor,

l is the thickness of the secondary winding.

The stated ratios D, d, l and L ensure the continuity and immobility of structural elements during measurements. The arrangement one under the other of two isolated from each other primary and secondary concentric windings, fixed on top of the frame, provides a better connection between the windings by reducing electromagnetic losses.

The sensor of the declared design ensures the reliability of its fastening during the measurement of the values of internal stresses in the rod elements, as well as the continuity of the monitoring process of such structures as cable-stayed and hanging systems, prestressed and ordinary reinforcement of reinforced concrete structures, load-bearing cables for drawbridges and lifting mechanisms.

In addition, high reliability is additionally ensured by taking into account the temperature of the frame of the sensor itself and the temperature of the rod element at each measurement of the magnitude of internal stresses in the rod element.

The utility model is illustrated by the following figures.

FIG. 1 shows a general view of an electromagnetic sensor with a rod ferromagnetic element placed inside its frame; FIG. 2 - longitudinal section AA of the electromagnetic sensor of the claimed design.

FIG. 3 shows a cross-section BB of an electromagnetic sensor of the claimed design.

FIG. 4 shows a block diagram of a system for monitoring the force impact on a ferromagnetic rod element using an electromagnetic sensor of the claimed design, where:

1 - ferromagnetic rod element (FSE) with a diameter D;

2 - FSE cable sheath 1;

3 - inner frame of an electromagnetic sensor with an outer diameter D2;

4 - secondary winding;

5 - a layer of insulating material;

6 - primary winding;

7 - temperature sensor of the inner frame;

8 - outer shell of the electromagnetic sensor;

9 - electromagnetic sensor;

10 - microcontroller;

11 - temperature sensor FSE 1;

12 - measuring unit;

13 - power unit;

14 - power supply unit of the power unit;

15 - operator panel;

16 - power supply unit of the monitoring system;

17 - temperature sensor of the monitoring device (inside the case), while

D1 - diameter of the primary winding,

D2 - diameter of the secondary winding,

L is the wall thickness of the inner frame of the sensor,

l is the thickness of the secondary winding.

The process of measuring internal stresses in the PSE 1 using an electromagnetic sensor 9 of the claimed design is carried out as follows.

Previously, the PSE 1 is placed inside the frame 3 of the electromagnetic sensor 9, forming an electromagnetic pair. Sensors 7 and 11 measure the temperature of the frame 3 of the electromagnetic sensor 9 and the temperature of the FSE 1, respectively. The monitoring system is calibrated before being installed on the structure. The system is placed in a special housing (not shown), in which the temperature sensor 17 is installed.

When power is supplied from a stabilized power source 14, in which the voltage of the power source is stabilized, the power unit 13 generates current pulses with a frequency and amplitude set by the microcontroller 10, and transmits it to the electromagnetic sensor 9, in which the PSE 1 is located.

In this case, the pulses are fed to the primary winding 6 of the sensor 9 and generate pulses in the secondary winding 4, due to inductive coupling.

According to the Villari effect, changing the length (size) of the PSE 1 changes its magnetic properties (magnetic permeability). Current pulses flowing through the primary winding 6 of the sensor 9 generate an alternating magnetic field in the region of the PSE 1. The change in magnetic properties during deformation of the PSE 1 can be detected by measuring the average voltage on the secondary winding 4 of the sensor 9.

The power unit 13 supplies amplified alternating current pulses to the sensor 9. The pulses hitting the primary winding 6 of the sensor 9 create pulses in the secondary winding 4 due to inductive coupling. Which, in turn, change their shape and values depending on the magnitude of the force effect σ arising on the PSE 1. Then the signal enters the measuring unit 12, which measures the value of the integral voltage U _avg from the secondary winding 4 of the sensor 9 and then transmits it to MK 10.

MK 10 calculates the magnitude of the load of the force action a on the PSE 1, taking into account the readings of temperatures T ₁ , T ₂ and T ₃ from the sensors 7, 11 and 17, as well as taking into account the values determined during calibration, according to a given mathematical relationship.

For further processing and interpretation of the digitized data, information from MK 10 is sent to the operator console 15, for example, to a PC via the USB interface.

Claims (8)

1. Electromagnetic sensor for measuring internal stresses in a bar ferromagnetic element of a building structure, including an inner frame of the sensor for placing a bar element, two located one under the other isolated from each other primary and secondary concentric windings, fixed over the frame, and the outer shell of the sensor, while D1 = D2 + 2 x l, D2 = D + 2 x L, where D - diameter of the bar element, D1 - diameter of the primary winding, D2 - diameter of the secondary winding, L is the wall thickness of the inner frame of the sensor, l is the thickness of the secondary winding. 2. Electromagnetic sensor according to claim 1, characterized in that the inner frame and the rod element are equipped with temperature sensors.

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