KR101935932B1 - Method for measuring dynamic elasticity using iet technique for cylinder shape - Google Patents

Abstract

The present invention relates to a method for measuring dynamic elasticity using IET method for a cylinder shape. Provided is measuring equipment comprising: a measuring instrument for generating a mechanical sound corresponding to a mechanical vibration by applying an impulse point impact by an impulse method on a test object of a cylinder shape structure, and converting the generated mechanical sound into an electrical signal; and a measuring terminal (computer) having a dedicated program installed therein and calculating a dynamic elasticity coefficient and a shear rate of the test object from an electrical signal inputted from the measuring instrument and then calculating a Poisson′s ratio of the subject using the calculated dynamic elasticity coefficient and the shear rate. Therefore, the dynamic elasticity coefficient, the shear rate, and the Poisson′s ratio of the test object of the cylinder shape structure can be more easily and stably measured.

Description

[0001] METHOD FOR MEASURING DYNAMIC ELASTICITY USING IET TECHNIQUE FOR CYLINDER SHAPE [0002]

The present invention relates to a method for measuring a dynamic modulus and a Poisson's ratio of an object to be inspected, and more particularly, to a dynamic elasticity measurement method using an IET technique (Impulse Excitation Technique, IET) will be.

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 of elasticity and Poisson's ratio using the resonance frequency found by applying a mechanical impact to a material specimen. Although this impulse method can be applied to a rectangular shape specimen, there is no equipment for measuring dynamic elastic modulus and Poisson's ratio from a cylindrical specimen, It is in the fact that it is not done.

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 method which can be utilized most simply and accurately and variously among dynamic measuring methods, And an object of the present invention is to provide a method of measuring dynamic elastic modulus and Poisson's ratio of an object using an impulse method capable of stably measuring dynamic elastic modulus and Poisson's ratio of the object.

According to an aspect of the present invention for achieving the above object, there is provided an apparatus for measuring an object to be inspected, 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; The resonance frequency of the subject is analyzed, and the resonance frequency of the subject and the input information of the subject are inputted, and then, And a measuring terminal for calculating a Poisson's ratio using the calculated dynamic modulus of elasticity and the front-end number, the method comprising the steps of: (a) measuring a dynamic elastic modulus and a Poisson's ratio of a cylinder- Inputting information on an object to be measured to the measuring terminal; (b) applying an impulse to the object using the measurement structure, 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 measurement 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 measured dynamic modulus of elasticity and the number of shear stages, and a method of measuring the dynamic modulus and Poisson's ratio of the subject using the impulse method do.

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 central portion of one side portion and placing the transducer microphone at an upper portion of the other side of the subject so as to receive the mechanical sound and convert it 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 a dynamic modulus of elasticity of the object to be inspected; (b-3) a machine sound is generated by impacting one side of the central part of the subject using the impulse tool in a state in which the subject is placed on top of any one of the pair of node lines, Placing the phonemes above the central portion of the subject to receive the mechanical sounds and converting them into electrical signals; (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 the information of the subject And measuring a dynamic modulus of elasticity of the object to be inspected.

Advantageously, said measuring instrument comprises a measuring die; A pair of node lines movably installed on the upper portion of the measurement die and supporting the test object; 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 the mechanical vibration generated in the subject by the impact of the impulse tool, converting the mechanical sound into an electrical signal, and transmitting the electrical signal to the measuring terminal; And a control unit.

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.

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 method on a test object of a cylindrical structure and converting the generated mechanical sound into an electric signal, And a measuring terminal (computer) for measuring a dynamic modulus and an anteroposterior coefficient of the subject from an electrical signal input from the measuring instrument and calculating a Poisson's ratio of the subject using the measured electrical signal, It is possible to more easily and stably measure the dynamic elastic modulus, the shear coefficient and the Poisson's ratio of the test object of the cylindrical structure.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view for explaining an elastic modulus and Poisson's ratio measuring instrument of an object using an impulse method according to an embodiment of the present invention; FIG.
FIGS. 2 and 3 are diagrams for explaining a method of adjusting the spacing of the node lines of the measuring instrument shown in FIG. 1. FIG.
FIG. 4 is a flowchart illustrating a method of measuring a dynamic modulus and Poisson's ratio of an object using an impulse method according to an embodiment of the present invention shown in FIG. 1;
5 is a view for explaining a method of measuring the dynamic elastic modulus of a cylindrical test object according to the present invention.
6 is a view for explaining a method of measuring the shear rate of a cylindrical inspected object according to the present invention.

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.

1 is a view for explaining an elastic modulus and Poisson's ratio measuring instrument of an object using an impulse method according to an embodiment of the present invention.

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

The measuring instrument 11 includes a measuring die 111 and a pair of node lines 112 which are installed on the measuring die 111 and on which the test object 2 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 2 placed on the object 2 and a mechanical sound generated in the object 2 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.

FIG. 2 and FIG. 3 are diagrams for explaining a method of adjusting the spacing of the node lines of the measuring instrument shown in FIG. 1, in which a pair of node lines 112 are arranged close to each other 3, when the measurer rotates the interval adjusting handle 115 in the clockwise direction, the pair of node lines 112 move to a uniform moving distance in a 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 2 to be measured, The object 2 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 2 from the amplified signal, (Mathematical algorithm) for calculating the elastic modulus and Poisson's ratio using the resonance frequency of the object 2 and information (shape, weight, length, width, thickness, etc.) of the object 2 to be inspected.

FIG. 4 is a flowchart illustrating a method of measuring the dynamic elastic modulus and Poisson's ratio of an object using an impulse method according to an embodiment of the present invention shown in FIG. 1. Referring to FIG.

Referring to FIGS. 1 and 4, information on the subject 2 is input through the measuring terminal 12 (ST1). At this time, the information of the subject 2 includes weight, length, width, thickness, and the like.

Thereafter, the subject 2 is placed on the node line 112 of the measuring instrument 11, and the subject 2 is impacted with an appropriate size using the impulse tool 113 to generate mechanical vibration (ST2) .

The transducer microphone 114 converts the mechanical sound corresponding to the mechanical vibration generated in the subject 2 by the impact of the impulse tool 113 into an electrical signal and transmits the electrical signal 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 (separates) the resonance frequency by analyzing the amplified electric signal, that is, the 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 front-end number is measured according to the following mathematical algorithm (exclusive program) by using the separated resonance frequency and the information of the subject 2, that is, the mass, thickness, length and width (ST6).

FIG. 5 is a view for explaining a method of measuring the dynamic elastic modulus of a cylindrical test object according to the present invention, and is a conceptual diagram illustrating impulse points and signal receiving points.

First, as shown in Figs. 1 and 5, the subject 2 is placed on the pair of node lines 112 such that the pair of node lines 112 are orthogonal to each other in the longitudinal direction. That is, the object 2 is placed on the upper side so as to extend in a direction orthogonal to the pair of node lines 112.

5, 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. The impulse point I is preferably located at the center of one side of the subject 2 in consideration of the characteristic of the dynamic elastic modulus of the test object 2 of the cylindrical structure. It is preferable to be located above the other side portion of the carcass 2. [

The measuring terminal 12 amplifies the electrical signal converted by the transducer microphone 114 and then separates the resonance frequency of the subject 2 from the amplified electrical signal and outputs the separated resonance frequency to the subject 2, The dynamic elastic modulus of the subject 2 is measured.

FIG. 6 is a view for explaining a method of measuring the shear rate of a cylindrical test object according to the present invention, and is a conceptual diagram illustrating impulse points and signal receiving points.

First, as shown in Figs. 1 and 6, the subject 2 is placed on the pair of node lines 112 such that the pair of node lines 112 are orthogonal to each other in the longitudinal direction. That is, the object 2 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. At this time, the impulse point (I) is set to be the same as the impulse point I when the subject 2 is placed on the pair of node lines 112 in consideration of the characteristic of the dynamic elastic modulus of the test object 2 having the cylindrical structure And the signal receiving point O is preferably located at the upper part of the central portion of the subject 2. [

The measurement terminal 12 amplifies the electrical signal converted by the transducer microphone 114, analyzes the resonance frequency of the subject 2 from the amplified electrical signal, and outputs the analyzed resonance frequency to the subject 2, The number of the front ends of the subject 2 is calculated.

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

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

Here, 'E' is the dynamic modulus of elasticity (Young's modulus), 'G' is the shear rate, 'μ' is the Poisson's ratio, 'm' is the mass of the subject, 'D' is the diameter of the subject, , '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 rod, 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 of the object to be inspected using the impulse method according to the embodiment of the present invention can be measured 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.

2: 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 (4)

A measuring instrument for generating a 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 inspection object into an electrical signal; The resonance frequency of the subject is analyzed, and the dynamic elastic coefficient and the frontal stage number are calculated based on the analyzed resonance frequency of the subject and information of the inputted subject, and the calculated dynamic elastic modulus and the frontal stage number are used And a measurement terminal for calculating a Poisson's ratio, the method comprising the steps of: measuring a dynamic elastic modulus and a Poisson's ratio of a cylinder-
(a) inputting information on an object to be measured to the measuring 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, And calculating the dynamic modulus of elasticity and the front-end number of the object to be inspected respectively using the information of the object to be inspected;
(b-1) the impulse tool is used to impinge the central portion of one side of the test subject in a state in which the test subject is placed on the pair of node lines so that a pair of node lines are orthogonal to each other, Placing the transducer microphone on an upper portion of the other side of the object to receive 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 a dynamic modulus of elasticity of the object to be inspected;
(b-3) a machine sound is generated by impacting one side of the central part of the subject using the impulse tool in a state in which the subject is placed on top of any one of the pair of node lines, Placing the phonemes above the central portion of the subject to receive the mechanical sounds and converting them into electrical signals;
(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 the information of the subject Calculating a dynamic modulus of elasticity and a front-end coefficient of the object to be inspected, the step of measuring the dynamic modulus of elasticity of the object to be inspected; And
(c) calculating a Poisson's ratio of the subject using the measured dynamic modulus of elasticity and the shear phase;
And measuring the dynamic elasticity of the cylinder shape using the IET technique.
delete The method according to claim 1,
The measuring instrument includes:
A measuring die;
A pair of node lines movably installed on the upper portion of the measurement die and supporting the test object;
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 the mechanical vibration generated in the subject by the impact of the impulse tool, converting the mechanical sound into an electrical signal, and transmitting the electrical signal to the measuring terminal;
Wherein the method comprises the steps of: (a) measuring a dynamic shape of the cylinder shape;
The method of claim 3,
The measuring instrument includes:
Transport means installed inside the measuring die and at least a part of which is combined with the pair of node lines to move the pair of node lines in a direction close to or away from each other; , &Lt; / RTI &gt;
Wherein the transferring means is manually controlled or operated through a gap adjusting handle provided on one side of the measuring die or is automatically controlled and operated by a motor.

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