KR101935930B1 - Apparatus and method for measuring dynamic modulus and poisson's ratio of an object using impulse technique - Google Patents

Abstract

The present invention relates to a device and a method for measuring a dynamic elastic modulus and a Poisson ratio for an object to be inspected using an impulse excitation technique (IET). Provided is a measuring device comprising: a measuring instrument which generates a mechanical sound corresponding to a mechanical vibration by applying an impulse point impulse to the object to be inspected, and converts the generated mechanical sound into an electrical signal; a dedicated program installed and the dynamic elasticity modulus of the object to be inspected calculated from the electrical signal inputted from the measuring instrument; and a measuring terminal (computer) for measuring a shear factor and calculating the Poisson ratio of the subject using the measured shear factor. Therefore, the dynamic elastic modulus, the shear factor, and the Poisson ratio of a quadrangular structure of the object can be more easily and stably measured.

Description

[0001] APPARATUS AND METHOD FOR MEASURING DYNAMIC MODULUS AND POISSON'S RATIO OF AN OBJECT USING IMPULSE TECHNIQUE [0002]

The present invention relates to an apparatus and method for measuring dynamic elastic modulus and Poisson's ratio of an object to be inspected, and more particularly, to an apparatus and method for measuring a dynamic elastic modulus and a Poisson's ratio of a quadrangular object using an Impulse Excitation Technique (IET) Measuring equipment and method thereof.

In general, the stiffness of a material means the ability to maintain its shape when the material undergoes any load, which is closely related to its thermal, mechanical, and physical properties Obtaining accurate input data on the elasticity of the material is very important in the field of structural analysis. The static method and the dynamic method are known as the methods of measuring the elastic modulus, which are considered to be important in material design and structural dynamics analysis.

The static measurement method is a method of obtaining the elastic modulus by measuring a corresponding amount of deformation after applying a certain external force through a tensile test or a strain gauge while the dynamic measurement method is a method of finding the resonance frequency of the material through sound waves or mechanical vibrations, The dynamic measurement method has the advantage of being more accurate and reproducible than the static measurement method and being relatively easy to measure.

Typical examples of the dynamic measurement method include a Resonance Technique that measures the dynamic elastic modulus and the Poisson's ratio by finding a resonance frequency using a sound wave, and a resonance technique in which an ultrasonic wave is passed through a material specimen, Ultrasonic Pulse Echo Overlap, which measures elastic modulus and Poisson's ratio, is known.

Resonance vibration method is a method to detect the natural frequency of the material by excitation of 5,000 ~ 20,000Hz and to measure the elastic modulus of the material by using it. It is limited to the cylindrical type specimen for the construction field. In recent years, we have been developing and applying the technology of receiving the excitation signal through the actuator. In particular, we have introduced the automobile manufacturer to evaluate the specifications of all materials related to automobiles in Korea. However, (Cubic: 10 × 10 × 10, Cylinder: 5 × 20L) is limited by the manufacturer's specification of the fixed precision standard of the specimen. Therefore, the measurement by the resonance vibration method is not free from measurement of various shapes and sizes .

Ultrasonic echo superimposition method is a method that is traditionally used. It is a method developed by a Japanese company and used by itself. At various speeds, a frequency is varied from 200 kHz to 20 MHz to measure a wave length regardless of the thickness of the specimen. (Microcracks, vacancies, dislocation pores, etc.) that affect obstacles in the progression of sound waves, and therefore, there is considerable difficulty in analyzing and evaluating the lattice defects.

Recently, Impulse Excitation Technique has been proposed and applied to measure the dynamic modulus and Poisson's ratio using the resonance frequency found by applying a mechanical impact to the material specimen. Although this impulse method has an advantage that it can be applied to a specimen of a rectangular shape, there is not provided a device for measuring the dynamic elastic modulus and Poisson's ratio easily from a rectangular specimen, It has not been done yet.

JP 10-2002-333437 A, Nov. 22, 2002. KR 10-2016-0038493 A, 2016 04. 07. KR 10-1329648 B1, 2013. 11. 08.

Therefore, the present invention has been proposed in order to solve the problems of the prior art, and the algorithm is established by theoretical / numerical analysis on the impulse technique which can be utilized most simply, accurately and variously among dynamic measurement methods, And an object of the present invention is to provide a dynamic elastic modulus and Poisson's ratio measuring instrument and method thereof for an object by using an impulse technique capable of stably measuring the dynamic elastic modulus and Poisson's ratio of a dead body.

According to one aspect of the present invention, there is provided a measuring instrument comprising: a measuring instrument for generating mechanical vibration by applying an impulse to an object to be inspected, and converting a mechanical sound corresponding to the mechanical vibration generated by the object into an electrical signal; And analyzing only the resonance frequency of the subject among the amplified signals after amplifying the electrical signal transmitted from the measuring instrument to a predetermined magnitude, and based on the analyzed resonance frequency of the subject and information of the inputted subject, And a measurement terminal for calculating the elastic modulus and the shear coefficient and calculating the Poisson's ratio using the calculated dynamic elastic modulus and the shear coefficient. The dynamic elastic modulus and Poisson's ratio measurement device for the object using the impulse technique Lt; / RTI >

Advantageously, said measuring instrument comprises a measuring die; A pair of node lines for supporting the object to be inspected; An impulse tool for applying an impulse to the object placed between the pair of node lines; And a transducer microphone for receiving a mechanical sound corresponding to a mechanical vibration generated in the subject by an impact of the impulse tool, converting the mechanical sound into an electrical signal, and transmitting the electrical signal to the measuring terminal.

Preferably, the measuring instrument further comprises a transporting means installed inside the measuring die, at least a part of which is coupled with the pair of node lines to move the pair of node lines in a direction close to or away from each other, The transfer means may be manually controlled or operated through a gap adjusting handle provided on one side of the measuring die, or may be automatically controlled and operated by a motor.

According to another aspect of the present invention, there is provided a method of measuring a dynamic elastic modulus and a Poisson's ratio of an object to be inspected having a square structure using the dynamic elastic modulus and Poisson's ratio of the object using the impulse technique, (A) inputting information about a subject to a measurement terminal; (b) applying an impulse to the object to be inspected using the measuring instrument, receiving the mechanical sound, converting the mechanical sound into an electrical signal, analyzing the resonance frequency of the object from the electrical signal using the measuring terminal, Calculating a dynamic modulus of elasticity and a front-end coefficient of the subject using the information of the subject; And (c) calculating a Poisson's ratio of the subject using the calculated dynamic modulus of elasticity and the shear phase number. The dynamic elastic modulus and Poisson's ratio measurement method for the subject using the impulse technique to provide.

Preferably, the step (b) includes the steps of: (b-1) placing the test object on the pair of node lines so that the pair of node lines are orthogonal to each other, Generating a mechanical sound by impacting the center, placing the transducer microphone at one side edge of the upper side of the subject, receiving the mechanical sound, and converting the mechanical sound into an electrical signal; (b-2) amplifying the electrical signal converted in the transducer microphone by the measuring terminal, analyzing the resonance frequency of the subject in the amplified electrical signal, and using the analyzed resonance frequency and the information of the subject Calculating an elastic modulus of the object; (b-3) generating a mechanical sound by impacting an upper side edge of the test object with the impulse tool in a state in which the test object is placed on top of any one of the pair of node lines, Placing the transducer microphone on the other upper edge of the subject to receive the mechanical sound and converting the mechanical sound into an electrical signal; And (b-4) amplifying the electrical signal converted in the transducer microphone by the measuring terminal, analyzing the resonance frequency of the subject in the amplified electrical signal, and using the analyzed resonance frequency and information of the subject And calculating a dynamic modulus of elasticity of the object to be inspected.

As described above, according to the present invention, a measuring instrument for generating a mechanical sound corresponding to a mechanical vibration by applying an impact to an impulse point by an impulse technique and converting the generated mechanical sound into an electric signal, A measuring terminal (computer) for calculating the dynamic elastic modulus and the front-end number of the subject from the electrical signal input from the measuring instrument, and then calculating the Poisson's ratio of the subject using the calculated dynamic elastic modulus and the front- It is possible to more easily and stably measure the dynamic elastic modulus, the shear coefficient and the Poisson's ratio of the quadrangular structure of the object to be inspected.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view for explaining an elastic modulus and Poisson's ratio measuring instrument for an object using an impulse technique according to an embodiment of the present invention; FIG.
Fig. 2 is a view showing a state in which a test object shown in Fig. 1 is seated to explain a configuration of the measuring instrument shown in Fig. 1; Fig.
FIGS. 3 and 4 are diagrams for explaining a method of adjusting the interval of the node lines of the measuring instrument shown in FIG. 2;
FIG. 5 is a flowchart illustrating a method of measuring a dynamic modulus and a Poisson's ratio using an impulse technique according to an embodiment of the present invention. Referring to FIG.
Figs. 6 and 7 are diagrams for explaining a method of measuring the dynamic modulus of elasticity of the test object shown in Fig. 2;
FIGS. 8 to 10 are diagrams for explaining a method of measuring the shear rate for the test object shown in FIG. 2;

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention, and how to accomplish them, will become apparent with reference to the embodiments described in detail below with reference to the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be embodied in various other forms.

The present embodiments are provided so that the disclosure of the present invention is not limited thereto and that those skilled in the art will fully understand the scope of the present invention. And the present invention is only defined by the scope of the claims. Accordingly, in some embodiments, well known components, well known operations, and well-known techniques are not specifically described to avoid an undesirable interpretation of the present invention.

In addition, like reference numerals refer to like elements throughout the specification. Moreover, terms used herein (to be referred to) are intended to illustrate embodiments and are not intended to limit the invention. In the present specification, the singular form includes plural forms unless otherwise specified in the specification. Also, components and acts referred to as " comprising (or comprising) " do not exclude the presence or addition of one or more other components and operations.

Unless defined otherwise, all terms (including technical and scientific terms) used herein may be used in a sense commonly understood by one of ordinary skill in the art to which this invention belongs. Also, commonly used predefined terms are not ideally or excessively interpreted unless they are defined.

Hereinafter, the technical features of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a view for explaining an elastic modulus and Poisson's ratio measuring instrument for an object using an impulse technique according to an embodiment of the present invention. FIG. 2 is a view for explaining the configuration of the measuring instrument shown in FIG. 1 Fig. 5 is a view showing a state in which the illustrated object is placed.

Referring to FIGS. 1 and 2, the elastic modulus and Poisson's ratio measuring instrument 10 for an object using an impulse technique according to an embodiment of the present invention includes a measuring instrument 11 and a measuring terminal 12. [

The measurement instrument 11 includes a measurement die 111 and a pair of node lines 112 installed on the measurement die 111 and on which the test object 1 is seated on top and a pair of node lines 112 An impulse tool 113 such as a small hammer for applying an appropriate impact to the object 1 placed on the object 1 and a mechanical sound generated in the object 1 by the impact of the impulse tool 113 are converted into electrical signals And a transducer microphone 114 for transmitting to the terminal 12.

The measuring die 111 is provided with a feeding means (not shown) for moving the pair of node lines 112 in a direction close to or away from each other in order to adjust an interval between the pair of node lines 112 have. At this time, the conveying means converts the rotational motion of the gap adjusting handle 115 provided at one side of the measuring die 111 into linear motion, and moves the node line 112 along the moving groove 111a of the measuring die 111 The ball screw may be a ball screw.

In the meantime, although the conveying means is manually controlled through the gap adjusting handle 115, it is also possible to automatically control the conveying means by using a motor instead of the gap adjusting handle 115 as an example. Accordingly, the interval between the pair of node lines 112 can be automatically adjusted in correspondence with the size (length, width) of the subject, thereby providing convenience in use.

The conveying means may be any one of an electric cylinder and a pneumatic cylinder.

3 and 4 are diagrams for explaining a method of adjusting the interval of node lines of the measuring instrument shown in Fig. 2, in which a pair of node lines 112 are arranged close to each other 4, when the measurer rotates the gap adjusting handle 115 clockwise, the pair of node lines 112 move in a uniform moving distance in the direction away from each other. On the contrary, when the gap adjusting handle 115 is rotated in the counterclockwise direction, the pair of node lines 112 move in the directions close to each other and the gap is adjusted.

As described above, the measuring instrument 10 according to the present invention can freely adjust the interval between the pair of node lines 112 through the gap adjusting handle 115 corresponding to the length of the subject 1 to be measured, The object 1 can be measured easily and stably.

1, the measuring terminal 12 amplifies the electrical signal converted through the transducer microphone 114, analyzes (separates) only the resonant frequency of the subject 1 from the amplified signal, (Mathematical algorithm) for calculating the elastic modulus and Poisson's ratio using the resonance frequency of the object 1 and information (shape, weight, length, width, thickness, etc.) of the object 1 to be inspected.

FIG. 5 is a flowchart illustrating a method of measuring a dynamic modulus and a Poisson's ratio of an object using an impulse technique according to an embodiment of the present invention. Referring to FIG.

Referring to FIGS. 1 and 5, information on the subject 1 is input through the measuring terminal 12 (ST1). At this time, the information of the subject 1 includes weight, length, width, thickness, and the like.

Thereafter, the subject 1 is placed on the node line 112 of the measuring instrument 11, and the subject 1 is impacted with an appropriate size using the impulse tool 113 to generate mechanical vibration (ST2) .

Thereafter, the transducer microphone 114 converts the mechanical sound corresponding to the mechanical vibration generated in the subject 1 by the impact of the impulse tool 113 into an electrical signal and transmits it to the measuring terminal 12 (ST3).

Then, the measuring terminal 12 receives the electrical signal corresponding to the mechanical sound measured by the transducer microphone 114 and amplifies the electrical signal to a predetermined magnitude (ST4).

Then, the measuring terminal 12 analyzes the amplified electrical signal, that is, the frequency to separate the resonance frequency (ST5). At this time, a method of finding the resonant frequency in the electrical signal can be found by finding a frequency having a maximum peak at a frequency having a plurality of peaks.

Then, the dynamic elastic modulus or the total number of steps is calculated in accordance with the following mathematical algorithm (exclusive program) by using the separated resonant frequency and the information of the object 1, that is, mass, thickness, length and width (ST6).

6 and 7 are diagrams for explaining a method of measuring the dynamic modulus of elasticity of the object to be inspected shown in FIG. 2, FIG. 6 is a conceptual diagram for explaining impulse points and signal receiving points, 7 is a conceptual diagram for explaining the characteristics of the dynamic elastic modulus generated in the test object when the impact by the impulse tool is applied to the test object shown in Fig.

First, as shown in Figs. 2 and 6, the test object 1 is placed on the pair of node lines 112 so that the pair of node lines 112 are perpendicular to each other in the longitudinal direction. That is, the object 1 is placed on the upper side so as to extend in a direction orthogonal to the pair of node lines 112.

6, the impulse tool 113 is used to impulse the impulse point I and simultaneously place the transducer microphone 114 at the signal receiving point O, And converts the mechanical sound generated by the impact into an electrical signal and provides it to the measuring terminal 12. 7, it is preferable that the impulse point I is located at the center of the subject 1 in consideration of the characteristic of the dynamic elastic modulus of the subject 1 having a rectangular structure, Is preferably positioned at one side edge of the object 1 to be inspected.

Thereafter, the measuring terminal 12 amplifies the electrical signal converted by the transducer microphone 114, separates the resonance frequency of the subject 1 from the amplified electrical signal, and outputs the separated resonance frequency to the subject 1, The dynamic elastic modulus of the object 1 is measured.

FIGS. 8 to 10 are diagrams for explaining a method of measuring the front end number of the test object shown in FIG. 2, wherein FIG. 8 is a view showing a state where the test subject is placed on a node line, FIG. 10 is a conceptual diagram for explaining impulse points and signal receiving points. FIG. 10 is a conceptual diagram for explaining the characteristics of the front-end number generated in the subject when the impact by the impulse tool is applied to the subject shown in FIG. to be.

The characteristics of the front end of the subject 1 show waveforms as shown in Fig. 10, so that the subject 1 is moved in the longitudinal direction on any one of the pair of node lines 112 An impulse point 113 located at one side edge of the upper side of the subject 1 in a state in which the subject 1 is seated on the node line 112 by using the impulse tool 113 as shown in Fig. (I). At this time, the signal receiving point O of the transducer microphone 114 is positioned at the other upper corner of the subject 1, and the mechanical sound generated by the mechanical vibration generated by the impulse tool 113 is received and converted into an electric signal do.

Then, the measuring terminal 12 amplifies the electrical signal converted by the probe microphone 114, analyzes (separates) the resonance frequency of the subject 1 from the amplified electrical signal, and outputs the analyzed resonance frequency to the subject (1) is used to calculate the front end number of the subject (1).

Then, the Poisson's ratio is calculated using the calculated dynamic elastic modulus or the number of shear stages (ST7).

[Equation 1] is an equation for calculating the Poisson's ratio of the subject.

'M' is the mass (g) of the subject, 'b' is the width (mm) of the subject, 'E' is the dynamic modulus of elasticity, 'G' is the shear modulus, , 'L' is the length (mm) of the subject, 't' is the thickness of the subject in mm, 'f _f ' is the fundamental resonant frequency of the subject in Hz, ₁ 'is the correction factor for the fundamental flexural mode to account for finite thickness of bar, Poisson's ratio, and so forth.

If L / t? ₂₀ , T ₁ can be simplified as shown in the following equation (2)

If L / t < 20, T ₁ is expressed by the following equation (3).

As described above, the dynamic elastic modulus and Poisson's ratio measurement method of the object using the impulse technique according to the embodiment of the present invention is performed by using the measuring instrument 10 according to the present invention shown in FIG. 1, After calculating the dynamic modulus of elasticity and the number of shear stages more easily and stably using the measuring instrument 11 and the measuring terminal 12 equipped with the dedicated program, the calculated dynamic elastic modulus and the front- Can be calculated.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

1: Subject
10: Measuring equipment
11: Measuring equipment
12: Measurement terminal (computer)
111: Measuring die
112: a pair of node lines
113: Impulse tool
114: Transducer microphone phone
115:

Claims (5)

An object of the present invention is to provide an apparatus and method for converting a mechanical sound corresponding to mechanical vibration generated in a subject into an electrical signal by applying an impulse to an object to be inspected and a pair of node lines for supporting the object, An impulse tool for applying an impulse to the subject placed between the pair of node lines, a mechanical sound corresponding to the mechanical vibration generated in the subject by the impact of the impulse tool, converting the electrical signal into an electrical signal, Further comprising a transfer means installed inside the measuring die and at least a part of which is coupled with the pair of node lines to move the pair of node lines in a direction close to or away from each other, Is manually controlled through an interval adjusting handle provided on one side of the measuring die Or, measuring Enclosures that are automatically controlled to operate by a motor; And
A resonance frequency of the object to be inspected is amplified to amplify the electrical signal transmitted from the measuring instrument to a predetermined magnitude, and the resonance frequency of the object to be inspected and the information of the inspected object, A measuring terminal for calculating a coefficient and a number of front ends, and calculating a Poisson's ratio using the calculated dynamic elastic modulus and the number of front ends;
Wherein the dynamic modulus and Poisson's ratio of the object are measured using an impulse technique. delete delete A method for measuring a dynamic modulus and a Poisson's ratio of a subject having a quadrangular structure using a dynamic elastic modulus and Poisson's ratio measuring instrument for an object using the impulse technique of claim 1,
(a) inputting information about a subject to a measuring terminal;
(b) applying an impulse to the object by using a measuring instrument, receiving the mechanical sound, converting the mechanical sound into an electrical signal, analyzing the resonance frequency of the object from the electrical signal using the measuring terminal, Calculating a dynamic modulus of elasticity and a front-end number of the subject using the information on the subject; And
(c) calculating a Poisson's ratio of the test object using the calculated dynamic modulus of elasticity and the shear phase number;
And measuring the dynamic modulus and Poisson's ratio of the object using the impulse technique.
5. The method of claim 4,
The step (b)
(b-1) While the object is placed on a pair of node lines so that a pair of node lines are orthogonal to each other, an impulse tool is used to impact the upper center of the object to generate a mechanical sound, Receiving the mechanical sound and converting the mechanical sound into an electrical signal;
(b-2) Transducer The electrical signal converted from the microphone is amplified by the terminal, the resonance frequency of the subject is analyzed by the amplified electrical signal, and the resonance frequency of the subject and the information of the subject are used to determine the elasticity Calculating a coefficient;
(b-3) In a state in which the subject is placed on top of any one of a pair of node lines, an impulse tool is used to impact the one side edge of the top of the subject to generate a mechanical sound, Receiving the mechanical sound and converting the mechanical sound into an electrical signal; And
(b-4) Transducer The electrical signal converted from the microphone is amplified by the terminal, and the resonance frequency of the subject is analyzed by the amplified electrical signal. The resonance frequency of the subject and the information Calculating an elastic modulus;
And measuring the dynamic modulus and Poisson's ratio of the object using the impulse technique.

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