KR20100002815A - Ultrasonic transducer for structural health monitoring(shm) by using the magnetostrictive effect - Google Patents

Abstract

PURPOSE: A non-contact ultrasonic transducer for SHM(Structural Health Monitoring) using magnetostrictive effect is provided to transmit and receive optimum induced ultrasonic wave by determining the shape of permanent magnet and coil which to have the largest magnetostriction coefficient when designing the probe. CONSTITUTION: A non-contact ultrasonic transducer for SHM(Structural Health Monitoring) using magnetostrictive effect comprises a control computer(10), an oscilloscope(20) which transmits a measurement signal to the control computer, a pulser/receiver(30) which creates ultrasonic pulses, an impedance matching unit(40), transmitting/receiving ultrasonic probes(50,60) which transmit/receive induced ultrasonic wave while not in contact with a target structure(200), and an amplifier(70) which amplifies the induced ultrasonic wave and transmits it to the pulser/receiver.

Description

Ultrasonic Transducer for Structural Health Monitoring (SHM) by Using the Magnetostrictive Effect

The present invention relates to a non-contact ultrasonic apparatus for assessing structural integrity using magnetostrictive effects. In particular, a magnetostrictive effect capable of non-destructive diagnosis by precisely inspecting a target structure using an originating / receiving ultrasonic probe capable of generating and receiving guided ultrasonic waves. The present invention relates to a non-contact ultrasonic device for structural integrity evaluation using the same.

In general, large industrial infrastructure, such as nuclear power, various power generation facilities, chemical plants, etc. is a very complex structure, causing a large accident that causes many casualties when an accident occurs, high safety and reliability are required.

In addition, in the case of such a structure, the inspection method for maintaining the safety of the system is very complicated, and the need for an efficient nondestructive evaluation (NDE) diagnostic technology is required to overcome the difficulty of the overall inspection of the entire system.

Therefore, in the case of a mechanical system that is very complex with a large machine structure, the overall understanding of the system and proper diagnosis techniques are required to predict the remaining life of the system and to maintain the safety of the system.

Currently, the NDE (Non Destructive Diagnosis) technology, which has been proved to be useful for securing the integrity of large structures periodically, is widely used for visual test (VT), penetration test (PT), magnetic particle test (MT), and radiographic test. The technique of obtaining relatively high quantitative test results such as RT, ultrasonic thickness measurement, ultrasonic test (UT), eddy current test (ECT), acoustic emission test (AE), etc. There are techniques with this.

In particular, the ultrasonic guided wave method is a wave that propagates along the geometric structure of a structure, and can be applied to the field of soundness evaluation of large structures because it can efficiently perform a wide range of non-destructive inspections. Compared to the point by point method using shear waves, the entire large structure can be inspected from a fixed point without moving the probe at once, and the inspection can be performed as it is without removing the insulator or coating material. Compared with the existing non-destructive technique, time and economical efficiency are excellent.

In addition, due to the insulation material and limited space, the inspector is difficult to access and complicated, or it is actively used for maintenance inspection of power generation equipment, which is difficult to detect far ultrasonic waves along the shapes of various inspected objects.

In addition, research on automated inspection systems is being conducted in advanced countries to evaluate the health of large structures more efficiently. Such automated inspection systems are ideally suited for inspection and evaluation using non-contact transducers. Current non-contact NDE techniques include air-coupled transducers, electro-magnetic acoustic transducers, and laser-based ultrasonics.

However, laser ultrasound has not solved the risk of material damage by laser irradiation, and remains at the level of basic research until now, and there are many problems to be solved in the field application.

In addition, the airborne ultrasonic probe is a complete non-contact non-destructive testing technique that can inspect several tens of millimeters in the non-contact state, but the scope of application for the improvement of objectivity and online Structural Health Monitoring (SHM) is rapidly expanding, It is difficult to develop a transducer because a lot of facility investment is required to develop a radio wave ultrasonic probe.

On the other hand, the design and manufacture of the electromagnetic ultrasonic transducer is easier to manufacture and the field applicability than other non-contact transducers. The reason is that the electromagnetic ultrasonic transducer can be easily generated by properly arranging the geometric shapes of the magnet and the coil according to the test specimen to generate various modes of ultrasonic waves (for example, longitudinal wave, transverse wave, guided ultrasonic wave, etc.). This is because the coil is easy to manufacture, and the field applicability is because the possibility has been experimentally verified by the following prior research.

Prior research included successful completion of R & D R & D project (Title: Development and Standardization of Non-Contact Non-Destructive Status Diagnosis Technology, Seoul National University). From the results of this previous study, we have experimentally verified the usefulness of the integrity evaluation of large structures using electromagnetic ultrasonic transducers and proposed the relevant standards for electromagnetic ultrasonic transducers.

 In addition, it successfully completed international industry-academic cooperation project (title: development of non-destructive ultrasonic wave simulation program for non-destructive status diagnosis) for industry-academic-industrial joint technology development project to foster and develop technology innovative enterprises. 6. 30) We developed a learning program that enables the inspector to easily understand the characteristics and behavior of the ultrasonic wave generated in the facility when performing non-destructive status diagnosis in the field.

However, the existing electromagnetic ultrasonic transducer has been applied by using the transmission and reception mechanism of the ultrasonic wave by Lorentz force. Most of the structures are made of magnetic material, which is greatly affected by the magnetostrictive effect rather than the Lorentz force, so there is a problem in that accurate measurement cannot be made.

In addition, a large structure is required for various electromagnetic ultrasonic transducers that are tailored to its shape due to various shapes, but since the demand depends on the introduction of foreign products, there is a problem in that the use range and technical independence are lowered.

Therefore, there is an urgent need for the development of ultrasonic transducers using magnetostrictive effects for structural health monitoring (SHM) and ultrasonic devices using ultrasonic transducers suitable for large-scale facilities.

Accordingly, the present invention compares the signal values of the guided ultrasonic waves, which are devised in view of the problems of the prior art, for structural integrity evaluation using a magnetostrictive effect applied to a probe designed to transmit / receive an optimal ultrasonic wave. It is an object to provide a non-contact ultrasonic apparatus.

Another object of the present invention is to select a permanent magnet that can exhibit the largest magnetostriction coefficient when the induced ultrasonic wave is transmitted to the test object, determine the coil shape, the installation structure of the permanent magnet and the coil, and allow the probe to be designed. Nondestructive diagnostics to maintain safety is to collect data for the prediction of the remaining life of the structure.

In addition, another object of the present invention is to obtain a measured value by matching the impedance value at the time of measurement by using an ultrasonic device to which an optimally designed transducer.

In addition, another object of the present invention is to amplify the received ultrasonic signal attenuated to obtain an accurate measurement value.

On the other hand, another object of the present invention is to install a non-contact on the surface of the target structure or structure and transmit and receive the ultrasonic wave generated by the transducer to perform the non-destructive diagnosis to maintain the safety of the structure to predict the remaining life of the structure data The collected signal can be used as data to predict the life of the structure.

In addition, another object of the present invention is to estimate the remaining life of the system required for proper maintenance and to maintain the safety of the system in the case of a very complex mechanical system and a large system structure in order to understand the overall system and the need for proper diagnostic technology The non-contact ultrasonic probe proposed to perform the non-destructive diagnosis in the range of up to several tens of meters is installed to analyze the signals obtained by transmitting and receiving guided ultrasonic waves propagating in the structure and to optimize the signal to maintain the safety and reliability of the structure. To provide.

In addition, another object of the present invention is to generate a guided ultrasonic wave using a non-contact ultrasonic probe to perform non-destructive diagnosis in a wide range ranging from a few m to several tens of meters to significantly shorten workability and working time economical This is an excellent and can be measured by a number of measuring methods without limiting the size of large structures.

In order to achieve the above object, the present invention provides a control computer for controlling command input, display of measured values, and generation of ultrasonic waves, an oscilloscope for transmitting a received signal measured to the control computer, and controlled and induced by a control computer. Impedance matching unit to improve the performance for measurement while matching the impedance (resistance) value of the pulser / receiver for generating the ultrasonic pulse affecting the generation of the ultrasonic wave, the pulser / receiver 30 and the transducer for transmitting the guided ultrasound Transmitted ultrasonic probe 50 for transmitting the guided ultrasonic wave in a state of being in contact with the target structure for measurement by receiving the ultrasonic pulse passed through the impedance matching unit, and the guided ultrasonic wave transmitted from the transmitted ultrasonic probe is transmitted along the target structure and changed. To a receiving ultrasonic transducer that receives the guided ultrasonic waves in a non-contact manner, and to a receiving ultrasonic transducer It is composed of an amplifier that receives and amplifies the received induction ultrasound and then delivers it to the pulser / receiver.The amplified induction ultrasound delivered to the pulser / receiver is received through an oscilloscope and then transmitted to the control computer. Characterized in that it is configured to represent the induced ultrasonic wave change value.

According to another embodiment of the present invention, the transmitting / receiving ultrasonic probe has a strength of the magnetic field of the permanent magnet related to the magnetostriction coefficient affecting the magnitude of the ultrasonic signal, the structure in which the coil is wound, and the arrangement (direction) of the permanent magnet and the coil. It provides a non-contact ultrasonic device for structural integrity evaluation using a magnetostrictive effect, characterized in that designed and configured according to.

As described above, the present invention has an effect that can be measured without being limited in the measurement range by applying a probe designed to transmit / receive an optimal ultrasonic wave by comparing the signal value of the measured ultrasonic wave.

And, when the guided ultrasonic wave is sent to the test object, it is possible to transmit and receive the optimal guided ultrasonic wave by determining the selection of the permanent magnet, the shape of the coil, the structure of the permanent magnet and the coil that can represent the largest magnetostriction coefficient, and the design of the transducer. It has an effect.

In addition, it is effective to measure the maximum signal value as well as the accurate measurement value by matching the impedance value in the measurement by using the ultrasonic device applying the optimally designed transducer.

In addition, another object of the present invention is to amplify the received ultrasonic signal attenuated, thereby obtaining an accurate measurement value.

On the other hand, non-destructive diagnostics to maintain the safety of the structure by transmitting and receiving the ultrasonic wave generated by the transducer and installed non-contact on the surface of the target structure or structure can collect data for the prediction of the remaining life of the structure and collected The signal has the effect of being used as data for predicting the life of the structure.

In addition, non-destructive diagnosis can be performed in a wide range ranging from several meters to several tens of meters by generating guided ultrasonic waves using a non-contact ultrasonic probe, which can significantly reduce workability and working time, resulting in excellent economy and size of large structures. There is an effect that can be measured by a number of measurement methods without limitation.

As described above, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

As shown in Figures 2 and 3, the non-contact ultrasonic device for structural integrity evaluation using the magnetostrictive effect of the present invention is a control computer 10, an oscilloscope 20 for transmitting the measured ultrasonic signal, a pulser for generating an ultrasonic pulse / Receiver 30, the impedance matching unit 40 to match the impedance value, the outgoing ultrasonic probe 50 for transmitting the guided ultrasonic wave to the target structure 200, the received ultrasonic probe 60 for receiving the transmitted guided ultrasonic wave The ultrasound apparatus 100 is configured to display the measured value on the control computer 10 through the pulser / receiver 30 and the oscilloscope 20 after being amplified by the amplifier 70 for amplifying the received ultrasonic wave. do.

The control computer 10 controls command input, display of measured values, and generation of ultrasonic waves. The control computer 10 inputs commands related to measurement and control by a measurer using a keyboard or a mouse method, and measures measured values (induced induction). Ultrasonic wave is changed through the target structure 200) is displayed to the numerical data or a graph, and the like to control the generation of the ultrasonic wave.

At this time, the control computer 10 may be configured using a general personal computer.

The oscilloscope 20 transmits the received signal measured to the control computer 10 to be displayed. The oscilloscope 20 outputs a change in input voltage with time on a screen so that the oscilloscope 20 can observe a signal having a rapid time change such as electric vibration or a pulse. In the present invention is configured to observe the ultrasonic signal.

The pulser / receiver 30 is controlled by the control computer 10 and is for transmitting ultrasonic pulses for generating the induced ultrasonic waves by the transmitting ultrasonic probe.

The impedance matching unit 40 is for improving the performance for measurement while matching the impedance (resistance) value of the pulser / receiver 30 and the transducer that transmits the guided ultrasonic wave, to obtain a suitable guided ultrasonic wave by matching the impedance value And it is configured to improve the transmission performance of the outgoing ultrasonic transducer (50).

The transmitting ultrasonic probe 50 is configured to serve as an ultrasonic sensor that transmits the guided ultrasonic waves in a state in which the guided ultrasonic waves passing through the impedance matching unit 40 are not in contact with the target structure 200 for measurement.

The received ultrasonic probe 60 is configured to receive the induced ultrasonic wave transmitted from the originating probe 50 along the target structure 200 in a non-contact manner.

At this time, the transmitting / receiving ultrasonic transducers 50 and 60 are designed according to the strength of the magnetic field of the permanent magnet related to the magnetostriction coefficient affecting the magnitude of the ultrasonic signal, the structure in which the coil is wound, and the arrangement (direction) of the permanent magnet and the coil. do.

That is, the transmission / reception ultrasonic transducers (50, 60) is composed of a coil located between the permanent magnet and the target structure 200 not shown in the drawings.

The amplifier 70 is configured to receive and amplify the guided ultrasonic wave received from the received ultrasonic transducer 60 and then transmit the amplified ultrasonic wave to the pulser / receiver 30.

Referring to the operation of the present invention configured as described above are as follows.

As shown in FIG. 2, the ultrasonic receiving transducer 60 is installed in the target structure 200 in a non-contact state, and the ultrasonic receiving transducer 60 is spaced apart at a predetermined distance from the point in line with the ultrasonic transmitting transducer 50. Install it.

Thereafter, the operator operates the control computer 10 to generate ultrasonic pulses in the pulser / receiver 30.

Next, the ultrasonic pulse generated through the pulser / receiver 30 passes the impedance matching unit 40 and transmits the ultrasonic pulse with the matching impedance to the transmitting ultrasonic probe 50.

In this way, the induced ultrasonic wave transmitted by the transmitting ultrasonic probe 50 is transmitted to the steel plate adopted as the target structure 200 in the present invention and then spread out in all directions, in which the receiving ultrasonic transducer 60 is transmitted along the steel plate. Guided ultrasonic waves are received in a non-contact state.

Here, explaining the ultrasonic generation principle of the outgoing ultrasonic transducer 50, the ferromagnetic material is passed through the Curie temperature (referring to the temperature at which the ferromagnetic changes from paramagnetic to paramagnetic), the magnetic domain (magnetic field is arranged parallel to each other between adjacent atoms) In general, permanent magnets are composed of several magnetic domains. The magnetostriction that occurs is called spontaneous magnetostriction.

In addition, when the magnetic field is applied to the material in which the magnetic domain is generated, the rearrangement of the magnetic domain occurs and the magnetostriction occurs. This is called magnetostriction by the addition of the external magnetic field.

As shown in Fig. 4, (a) is an atomic arrangement state of the ferromagnetic material at a temperature higher than the Curie temperature. Form and magnetostriction occurs. If a magnetic field is added from the outside, as shown in (c), the magnetic moment of atoms in the magnetic sphere is aligned in one direction, and magnetostriction also occurs. Magnetostrictive sensors used for non-destructive diagnostics utilize magnetostrictive characteristics due to the addition of external magnetic fields.

In addition, when an alternating magnetic field is applied to the magnetic material, the material vibrates. The phenomenon of size change according to the magnetic field is called magnetostriction or magnetostriction, and this phenomenon is called a Joule effect. The Joule effect refers to a phenomenon in which a physical deformation (length, volume change) of a permanent magnet is induced by a change in the magnetic field generated around the coil when a current pulse flows through the coil installed around the magnetic material.

On the other hand, the induced ultrasonic wave received by the ultrasonic probe 60 is attenuated due to the attenuation is weaker than when the transmission is amplified in order to accurately determine the measured value through the amplifier 70.

In addition, looking at the ultrasonic reception principle of the ultrasonic receiving probe 60, the change of the magnetic field occurs when the length of the material in the magnetic field is called the Villari effect (Villari) effect.

Here, the Villari effect is a phenomenon in which a mechanical deformation occurs due to an elastic wave in a magnetic body, which causes a change in the induced magnetic field of the magnetic body. When a coil is installed around the magnetic body, the change in the magnetic field can be measured as a change in voltage. do.

As such, by using the relation between the magnetic field and the deformation of the material, ultrasonic waves may be generated in the target structure 200, and vice versa, so that the ultrasonic signals may be detected and thus may be applied to ultrasonic inspection.

At this time, the ultrasonic wave amplified by the amplifier 70 is transmitted to the control computer 10 at the same time the ultrasonic signal is displayed on the oscilloscope 20 via the pulser / receiver 30, the data is stored with the display of the measured value, It can be used as data for non-breakthrough diagnosis.

In the above, the present invention has been illustrated and described with reference to specific preferred embodiments, but the present invention is not limited to the above-described embodiments and is not limited to the spirit of the present invention. Various changes and modifications can be made by those who have

1 is a conceptual diagram showing the ultrasonic generation principle of a conventional non-contact ultrasonic sensor using Lorentz force,

2 is a block diagram for transmitting and receiving the ultrasonic wave using a non-contact ultrasonic transducer according to the present invention,

3 is a view showing the shape of the coil which is located between the transmission / reception ultrasonic probe and the target structure according to the present invention affects the transmission / reception of the induced ultrasonic wave,

Figure 4 is a conceptual diagram showing the ultrasonic generation principle of the non-contact transmission ultrasonic probe using the magnetostrictive effect in accordance with the present invention.

<Description of Symbols for Main Parts of Drawings>

10: control computer 20: oscilloscope

30: pulser / receiver 40: impedance matching unit

50: outgoing ultrasonic transducer 60: received ultrasonic transducer

70: amplifier 100: ultrasonic device

200: target structure

Claims (2)

A control computer 10 for controlling command input, display of measured values, and generation of ultrasonic waves; An oscilloscope 20 for transmitting the received signal measured to the control computer 10, and A pulser / receiver 30 for generating ultrasonic pulses controlled by the control computer 10 and influencing the generated ultrasonic waves, An impedance matching unit 40 for improving the performance for the measurement while matching the pulser / receiver 30 with the impedance (resistance) value of the transducer for transmitting the induced ultrasonic waves; An outgoing ultrasonic probe 50 for receiving the ultrasonic pulses passing through the impedance matching unit 40 and transmitting the induced ultrasonic waves in a non-contact state to the target structure 200 for measurement; A receiving ultrasonic probe 60 which receives the induced ultrasonic wave transmitted from the transmitting probe 50 along the target structure 200 and receives the changed induced ultrasonic wave in a non-contact manner; Amplified induction ultrasonic wave transmitted to the pulser / receiver 30 is composed of an amplifier 70 that receives and amplifies the received ultrasonic wave received from the receiving ultrasonic transducer 60 and then transmits the amplification to the pulser / receiver 30. 20) A non-contact ultrasonic apparatus for structural soundness evaluation using magnetostrictive effects, characterized in that it is transmitted to the control computer (10) and then displayed to show the induced ultrasonic wave change value by various data values or graphs. According to claim 1, The transmitting / receiving ultrasonic transducer (50, 60) is a magnetic field strength of the permanent magnet related to the magnetostriction coefficient affecting the magnitude of the ultrasonic signal, the structure in which the coil is wound, the arrangement of the permanent magnet and coil ( Non-contact ultrasonic apparatus for structural integrity evaluation using magnetostrictive effect, characterized in that the design is configured according to the direction).

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