KR20200085088A - Natural frequency measurement system of structures using the Lorentz force - Google Patents

Abstract

According to the present invention, provided is a device for measuring the natural frequency of a structure using Lorentz force which comprises: an excitation means for applying an impact to a structure with a vibrator linearly moved by an electromagnetic field by being arranged close to a structure to be measured; a sensor mounted on one side surface of the structure to be measured to detect the vibration of the structure; and a vibration measuring unit electrically connected to the excitation means and the sensor, controlling the amount of impact of the excitation means, and calculating and measuring natural vibration which are transmitted through the sensor. Lorentz force is generated by using current flowing through a permanent magnet and a coil to control the amount of impact of an exciter colliding with the structure to be measured with the Lorentz force so as to obtain a constant result, thereby increasing the reliability of the result. Also, the magnitude of the amount of impact is precisely adjusted by the strength of the electromagnetic field to obtain a result with high reliability even though the shape of a structure to be measured is complicated.

Description

Natural frequency measurement system of structures using the Lorentz force

The present invention relates to a device for measuring the natural frequency of a structure using a Lorentz force, and more specifically, to generate a Lorentz force using a current flowing in a permanent magnet and a coil, the exciter that collides against the structure to be measured with the Lorentz force. It relates to a device for measuring the natural frequency of a structure using a Lorentz force that can obtain a certain result by controlling the amount of impact.

Generally, there are various methods for analyzing the dynamic behavior characteristics of a structure, but as a widely used method, a test method for measuring the natural frequency characteristics of a structure is used.

The method for testing the natural vibration characteristics of these structures calculates the transfer function that combines the excitation signal and the response signal measured by a sensor capable of detecting the vibration of the structure under vibration excitation conditions, and modulates the natural frequency and the corresponding behavior characteristics (mode type) Mode Shape).

A device for measuring the natural vibration characteristics of a conventionally provided structure mounts the structure on a support, excites the structure with an excitation means such as an impact hammer, and can detect vibration generated here, such as an accelerometer. A method of analyzing natural vibration characteristics was used by attaching a contact sensor to a structure causing the excitation using a pneumatic cylinder or adhesive, and transmitting the signal generated therein to the analysis device.

Here, the impact hammer transmits the excitation force to the structure by manually striking the structure as if the experimenter hits the hammer. The impact hammer has a small excitation force, but is easy to operate, and is mainly used for vibration tests or small structures of the building floor system.

Such a conventional impact hammer has a head part that can be replaced by selecting a shock tip of a material that can add sufficient impact depending on the structure, and a force sensor that detects the impact force generated between the head and the structure and converts it into an electrical signal. And, it is configured to include a handle coupled to the head portion so that the user can easily take off.

The user holds the handle of the impact hammer as described above and strikes the bottom surface with the head portion so that the head portion comes into contact with the bottom surface, thereby generating impact force and vibration. At this time, a force sensor is installed in the head portion, which is generated by the head portion It is possible to measure the characteristics of the impact force.

However, such an impact hammer has the advantage of being easy to carry and operate as described above, but has a disadvantage that it is difficult to perform a successful experiment without an experienced experimenter, because the impact hammer is an experiment manually handled by the experimenter. This is because each person has a different method of hitting the hammer, so it is difficult to obtain a constant excitation force.

Of course, the exact same excitation force is not necessarily required in the vibration test, but if the fluctuation of the excitation force becomes large, the possibility of an experimental error in the experimental result increases greatly. If you do, you cannot get the exact vibration frequency component.

Therefore, hitting the impact hammer vertically is not easy unless you are an experienced experimenter, and even an experienced experimenter will naturally decrease the frequency of hitting accurately with hundreds of hits in one experiment.

In the prior art publication patent No. 10-2012-0133641 (2012.12.11), a shock head for applying a shock to a structure, a housing for guiding the shock head in one-dimensional motion, and a reciprocating elastic motion connected to the rear of the shock head A shock excitation device comprising an inducing spring, and a shock excitation drive device connected to the spring to trigger movement of the shock head, and measuring a vibration signal including a natural frequency of the structure according to the shock transmitted to the structure It provides a natural frequency measuring device using a one-dimensional elastic shock, characterized in that it comprises a measurement sensor, and a central control device for controlling the shock excitation device and the measurement sensor, and outputting the measured signal.

The present invention generates a Lorentz force using a current flowing in a permanent magnet and a coil, and by using the Lorentz force, the impact amount of an exciton that collides against a structure to be measured is controlled to obtain a certain result, thereby improving the reliability of the result. An object of the present invention is to provide an apparatus for measuring the natural frequency of a structure using Lorentz force that can obtain a reliable result even if the shape of the structure to be measured is complicated by precisely controlling the magnitude of the impact amount to the intensity of the electromagnetic field.

The apparatus for measuring the natural frequency of a structure using a Lorentz force according to the present invention is disposed close to a structure to be measured, and an excitation means for applying a shock to the structure with an excitation that moves linearly by an electromagnetic field, and one side of the structure to be measured Vibration measurement that is mounted on the sensor for sensing the vibration of the structure, and electrically connected to the excitation means and the sensor, to control the impact amount of the excitation means, and calculate and measure natural vibration with the vibration transmitted through the sensor Includes wealth.

At this time, the excitation means according to the present invention is a guide tube having a predetermined hollow formed therein, and is movably inserted along the hollow of the guide tube, and optionally moves along the hollow to vibrate the structure to be measured, A plurality of permanent magnets provided in the vibrator, a coil member disposed at the rear of the guide tube to form an electromagnetic field with an externally applied power source, and a coil member for linearly moving the vibrator with a Lorentz force, and the coil member electrically It may be connected, and may include a switch unit for selectively applying power so that an electromagnetic field is generated in the coil member, and a power supply unit electrically connected to the switch unit to provide power with a corrected capacity from the outside.

In addition, the excitation means according to the present invention is a guide tube having a predetermined hollow formed therein, and is movably inserted along the hollow of the guide tube, and selectively moves along the hollow to vibrate and collide against a structure to be measured , A plurality of permanent magnets provided in the vibrator, a coil member disposed around the outer periphery of the guide tube to form an electromagnetic field with a power applied from the outside, and a coil member for linearly moving the vibrator with a Lorentz force, and the coil member And it is electrically connected, it may include a switch unit for selectively applying power to generate an electromagnetic field to the coil member, and a power supply unit that is electrically connected to the switch unit and provides a power of correcting capacity from the outside.

Here, it is preferable that the permanent magnet according to the present invention is composed of a Halbach array in which a plurality of magnetization directions are rotated by 90°.

In addition, one end is connected to the rear of the vibrator according to the present invention, the other end is connected to the rear end of the guide tube, and after the vibrator collides with the structure to be measured, the elastic force is returned to a corresponding position. It further includes a return spring that provides elasticity.

The effects of the natural frequency measuring device of the structure using the Lorentz force according to the present invention are as follows.

First, by generating a Lorentz force using a current flowing in a permanent magnet and a coil, the Lorentz force controls the impact amount of an exciton that strikes a structure to be measured, and a certain result can be obtained, improving the reliability of the result. Have

Second, the magnitude of the impact amount is precisely adjusted to the strength of the electromagnetic field, so that even if the shape of the structure to be measured is complex, it has an effect of obtaining reliable results.

1 is an exemplary view showing a device for measuring a natural frequency of a structure using a Lorentz force according to an embodiment of the present invention.
2 is an exemplary view showing a state in which the coil according to an embodiment of the present invention is wound on the outer periphery of the guide tube.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, the terms or words used in the present specification and claims should not be construed as being limited to ordinary or lexical meanings, and the inventor appropriately explains the concept of terms to explain his or her invention in the best way. Based on the principle that it can be defined, it should be interpreted as meanings and concepts consistent with the technical spirit of the present invention.

Therefore, the embodiments shown in the embodiments and the drawings described in this specification are only the most preferred embodiments of the present invention, and do not represent all of the technical spirit of the present invention, and at the time of this application, they can be replaced evenly It should be understood that there may be variations.

The present invention generates a Lorentz force using a current flowing in a permanent magnet and a coil, and the Lorentz force controls the impact amount of an exciton that strikes a structure to be measured with the Lorentz force, so that the uniqueness of the structure using the Lorentz force to obtain a constant result Regarding the frequency measuring device, referring to the drawings in more detail as follows.

The natural vibration measuring apparatus according to an embodiment of the present invention with reference to FIGS. 1 and 2 includes an excitation means 100, a sensor 200, and a vibration measurement unit 300. First, the excitation means 100 is avoided. It is disposed close to the structure (1) to be measured, and impacts the structure (1) with an exciter (120) that moves linearly by an electromagnetic field.

At this time, the excitation means 100 includes a guide tube 110 in which a predetermined hollow is formed therein, wherein the guide tube 110 has one end close to the structure 1 open, and the other end opposite to each other. It is preferable to form a closed shape with a horizontal wall, and an incision is formed on the upper side, so that the vibrator 120 can be electrically connected to the vibration measuring unit 300.

The guide tube 110 is provided with the vibrator 120 in the hollow, and the vibrator 120 is linearly movable along the hollow of the guide tube 110, and optionally linearly along the hollow Move to and the front collides with the structure 1 to be measured.

And the vibrator 120 is provided with a plurality of permanent magnets 121, the plurality of permanent magnets 121 is to the rear side of the vibrator 120 so that the magnetic flux density of the induced permanent magnet can be maximized The plurality of magnetization directions may be configured as a Halbach array arranged by rotating by 90°.

In addition, the coil member 111 is disposed at the rear of the guide tube 110, the coil member 111 forms an electromagnetic field with a power applied from the outside, the linear force of the vibrator 120 by Lorentz force To move.

Here, the coil member 111 is not limited to being disposed only behind the guide tube 110 as described above, and as shown in FIG. 2, the coil member 111 is along the outer periphery of the guide tube 110. The windings are arranged to form an electromagnetic field with a power applied from the outside, and the vibrator 120 may be linearly moved by a Lorentz force.

In addition, the coil member 111 and the switch unit 130 is electrically connected, the switch unit 130 selectively applies power so that an electromagnetic field is generated in the coil member 111.

In addition, the switch unit 130 and the power supply unit 140 are electrically connected, and the power supply unit 140 provides power with a corrected capacity from the outside.

Here, a return spring 122 is provided at the rear of the vibrator 120, wherein one end of the return spring 122 is connected to the rear of the vibrator 120, and the other end has the guide tube 110. ) Is connected to the closed rear end, and after the vibrator 120 collides with the structure 1 to be measured, the elastic force is provided to return to the corresponding position with the elastic force.

Therefore, by the above-described configuration, the vibrator 120, when power is applied to the coil member 111, the Lorentz force between the coil member 111 and the permanent magnet 121 disposed in a Halbach array ( Lorentz force) is generated, and collides with the structure 1 while moving linearly along the hollow, which is the longitudinal direction of the guide tube 110, according to the direction of the current applied to the coil member 111.

At this time, the moving direction of the vibrator 120 can be selected in the direction of the current, and since the impact amount of the vibrator 120 can be controlled by the intensity of the current, a certain result can be obtained through a constant impact amount.

Here, after the vibrator 120 is collided with the structure 1, and is not collided (double hit), after being positioned in the correct position in the hollow of the guide tube 110 in the elasticity of the return spring 122 When the power is applied to the coil member 111 again over time, a collision occurs again.

It is possible to adjust the vibrator 120 so that the guide tube 110 is positioned in the correct position during the hollow by the Lorentz force generated by the direction and intensity of the current applied to the coil member 111. .

In addition, the sensor 200 is mounted on one side of the structure 1 to be measured to sense vibration of the structure.

In this case, the sensor 200 is a conventional vibration sensor, and a sensor of a piezoelectric acceleration method and a cantilever vibration method may be selectively employed according to the frequency of the structure 1.

In addition, the vibration measuring unit 300 is electrically connected to the excitation means 100 and the sensor 200 to control the amount of impact of the excitation means 100, and to the vibration transmitted through the sensor 200 Measure by calculating the natural vibration.

The present invention has been described with reference to the embodiments shown in the drawings, but these are merely exemplary, and those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom. Therefore, the true technical protection scope of the present invention should be determined by the technical spirit of the appended claims.

1: Structure
100: means of excitation
110: guide tube
111: coil member
120: excitation
121: permanent magnet
122: return spring
130: switch unit
140: power supply
200: sensor
300: vibration measurement unit

Claims (5)

An excitation means disposed adjacent to the structure to be measured and linearly moved by an electromagnetic field to excite the structure;
A sensor mounted on one side of the structure to be measured to sense vibration of the structure; And
Vibration measurement unit that is electrically connected to the excitation means and the sensor, controls the amount of impact of the excitation means, and calculates and measures natural vibration by vibration transmitted through the sensor; Measuring device.
The method according to claim 1,
The excitation means
A guide tube having a predetermined hollow formed therein;
An exciter that is movably inserted along the hollow of the guide tube and selectively moves along the hollow to collide with the structure to be measured;
A plurality of permanent magnets provided in the vibrator;
A coil member disposed at the rear of the guide tube to form an electromagnetic field with a power applied from the outside to linearly move the vibrator with a Lorentz force;
A switch unit electrically connected to the coil member to selectively apply power so that an electromagnetic field is generated in the coil member;
A device for measuring the natural frequency of a structure using a Lorentz force, including; a power supply unit electrically connected to the switch unit and providing a power supply with a corrected capacity from the outside.
The method according to claim 1,
The excitation means
A guide tube having a predetermined hollow formed therein;
An exciter that is movably inserted along the hollow of the guide tube and selectively moves along the hollow to collide with the structure to be measured;
A plurality of permanent magnets provided in the vibrator;
A coil member disposed around the outer periphery of the guide tube to form an electromagnetic field with a power applied from the outside, and linearly moving the vibrator with a Lorentz force;
A switch unit electrically connected to the coil member to selectively apply power so that an electromagnetic field is generated in the coil member;
A device for measuring the natural frequency of a structure using a Lorentz force, including; a power supply unit electrically connected to the switch unit and providing a power supply with a corrected capacity from the outside.
The method according to any one of claims 2 and 3,
The permanent magnet
A device for measuring the natural frequency of a structure using a Lorentz force, characterized in that a plurality of magnetization directions are arranged by rotating the rotation angle by 90°.
The method according to any one of claims 2 and 3,
One end is connected to the rear of the vibrator, and the other end is connected to the rear end of the guide tube, and after the vibrator collides with the structure to be measured, an elastic spring provides elastic force to return to the corresponding position with elastic force. ; Natural frequency measurement device of the structure using the Lorentz force further comprising.

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