KR102557214B1 - Ultrasonic fatigue testing apparatus - Google Patents

Abstract

The present invention relates to an ultrasonic fatigue testing apparatus, comprising: a piezoelectric transducer disposed on one side of a test piece; An amplification horn that amplifies vibration generated by the piezoelectric transducer and transmits it to the test piece, and includes a first amplification horn connecting the piezoelectric transducer and one end of the test piece and a second amplification horn disposed at the other end of the test piece; a displacement sensing unit measuring the displacement of the test piece by detecting the amplitude and frequency of the vibration generated in the test piece by the vibration supplied from the piezoelectric transducer; and a driving module for providing a preset tensile force to one side of the test piece by moving the first amplifying horn.

Description

Ultrasonic Fatigue Testing Apparatus {ULTRASONIC FATIGUE TESTING APPARATUS}

The present invention relates to an ultrasonic fatigue test apparatus, and more particularly, to an ultrasonic fatigue test apparatus configured to apply a regular fatigue stress to a test piece using a strain gauge module and an optical sensor module to improve the accuracy and reliability of a fatigue test. It is about the test device.

In general, an ultra-high cycle fatigue tester or ultrasonic fatigue tester is a device that uses a piezoelectric transducer to generate vibration with a frequency in the ultrasonic range and applies it to a test piece to perform a fatigue test. It is used for fatigue tests on parts where resistance to fatigue stress is important, such as blades.

An ultra-high cycle fatigue test apparatus according to the prior art is a piezoelectric transducer provided in the upper region of a test piece, a piezoelectric transducer and an amplifying horn for amplifying vibration generated by the piezoelectric transducer and transmitting it to the test piece by connecting the piezoelectric transducer and the upper end of the test piece, and the piezoelectric transducer A power generator for applying a predetermined power is included.

Here, the piezoelectric transducer converts electrical energy into mechanical energy using a material with a piezoelectric effect, and converts mechanical energy into electrical energy. generate mechanical vibrations.

However, since the ultra-high cycle fatigue test apparatus according to the prior art having the above configuration transmits vibration only to one end of the test piece by one piezoelectric transducer and an amplification horn, the displacement and strain generated in the longitudinal direction of the test piece The waveform is not symmetric about the center.

Accordingly, the fatigue test apparatus according to the prior art has a problem in that reliability of the fatigue test is reduced because irregular fatigue stress is applied to the center of the test piece.

In addition, since the ultra-high cycle fatigue test apparatus according to the prior art is in the form of a cantilever in which one end of the mounted test piece is provided as a fixed end and the other end as a free end, it is difficult to apply a predetermined tensile or compressive force to the test piece. There were limitations in terms of the diversity of the test.

Therefore, one end and the other end of the test piece are set as fixed ends, and a predetermined tensile force is applied to one end side, so that various stress ratios of the test piece can be adjusted, as well as a strain gauge module that measures the strain of the test piece and irradiation that is spaced apart and projected on the test piece. Development of an ultrasonic fatigue test apparatus that can improve the accuracy and reliability of a fatigue test by including an optical sensor module that senses light to derive a calibrated stress of a test piece and apply a regular fatigue stress to the test piece is required. .

[Patent Document] KR 10-2148977 (registration date: August 21, 2020)

In order to solve the above problems, the present invention, an amplification horn including a first amplification horn connecting the piezoelectric transducer and one end of the test piece and a second amplification horn disposed at the other end of the test piece, supplied from the piezoelectric transducer By including a displacement sensing unit for measuring the displacement of the test piece by detecting the amplitude and frequency of the vibration generated in the test piece by vibration, and a driving module for moving the first amplifying horn to provide a preset tensile force to one side of the test piece, With one end and the other end as fixed ends, it is configured so that a predetermined tensile force acts on one end side, so that various stress ratios of the test piece can be adjusted, as well as a strain gauge module that measures the strain of the test piece and is spaced apart to sense the irradiation light projected on the test piece. The purpose is to provide an ultrasonic fatigue test apparatus that can improve the accuracy and reliability of the fatigue test by deriving the calibration stress of the test piece and applying regular fatigue stress to the test piece.

Ultrasonic fatigue test apparatus according to an embodiment of the present invention for achieving the above object is a piezoelectric transducer disposed on one side of the test piece (Ultrasonic Transducer); An amplification horn that amplifies vibration generated by the piezoelectric transducer and transmits it to the test piece, and includes a first amplification horn connecting the piezoelectric transducer and one end of the test piece and a second amplification horn disposed at the other end of the test piece; a displacement sensing unit measuring the displacement of the test piece by detecting the amplitude and frequency of the vibration generated in the test piece by the vibration supplied from the piezoelectric transducer; and a driving module for providing a preset tensile force to one side of the test piece by moving the first amplifying horn.

In addition, the test piece according to the present invention is characterized in that the stress ratio of the test piece is adjusted by performing a fatigue test in a state in which the other end is fixed by the second amplifying horn and a tensile force is applied to one end side by the driving module.

In addition, the displacement sensing unit according to the present invention may include a strain gauge module attached to one side of the test piece and sensing a strain of the test piece; and a non-contact optical sensor module disposed at a predetermined distance from one end of the test piece and measuring the ultrasonic vibration of the test piece by sensing the projected irradiation light.

In addition, the ultrasonic fatigue test apparatus according to the present invention receives displacement data output from the displacement sensing unit as feedback in real time, and controls the magnitude and frequency of power provided to the piezoelectric transducer so that the length of the test piece is included in a predetermined reference range. It is characterized by including;

In addition, the controller according to the present invention is characterized in that the calibration displacement data of the test piece is derived by calibrating the displacement value measured by the strain gauge module and the displacement value measured by the optical sensor module.

In addition, the controller according to the present invention calculates the dynamic Young's modulus of the test piece by reflecting the displacement value information measured by the displacement sensing unit, and calculates the fatigue test result using the calculated dynamic elastic modulus. It is characterized by derivation.

According to the ultrasonic fatigue test apparatus according to the present invention as described above, one end and the other end of the test piece are set as fixed ends, and a preset tensile force is applied to one end side, so that various stress ratios of the test piece can be adjusted and the strain of the test piece is measured It is configured to apply regular fatigue stress to the test piece by deriving the correction stress of the test piece, including a strain gauge module and an optical sensor module that is spaced apart and senses the irradiation light projected on the test piece, thereby improving the accuracy and reliability of the fatigue test. There are possible effects.

1 is a first configuration diagram showing the overall configuration of an ultrasonic fatigue testing apparatus according to the present invention.
2 is a second configuration diagram showing the overall configuration of an ultrasonic fatigue testing apparatus according to the present invention.
3 is a mechanical diagram for stress calibration of the ultrasonic fatigue testing apparatus according to the present invention.
4 is a first graph showing the stress ratio and average stress control according to the present invention by way of example.
5 is a second graph exemplarily showing stress ratio and average stress control according to the present invention.
6 is a diagram showing a program for setting stress ratio adjustment according to the present invention.
7 is a photograph showing the overall configuration of the ultrasonic fatigue test apparatus according to the present invention.
8 is a graph showing the stress of a test piece in a fatigue test apparatus in which only one end of the test piece is installed as a fixed end.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. First of all, it should be noted that identical components or parts in the drawings are denoted by the same reference numerals as much as possible. In describing the present invention, detailed descriptions of related known functions or configurations are omitted so as not to obscure the gist of the present invention.

1 is a first configuration diagram showing the overall configuration of an ultrasonic fatigue testing apparatus according to the present invention, FIG. 2 is a second configuration diagram showing the overall configuration of an ultrasonic fatigue testing apparatus according to the present invention, and FIG. This is a picture showing the overall configuration of the ultrasonic fatigue test device according to

As shown in FIGS. 1, 2 and 7, the ultrasonic fatigue test apparatus 1 according to the present invention includes a piezoelectric transducer 100, an amplifying horn 200, a displacement sensing unit 300, a driving module 400, and A controller 500 may be included.

The piezoelectric transducer 100 may be disposed on one side of the test piece (S).

Specifically, the piezoelectric transducer 100 is a device that converts electrical energy into mechanical energy using a material having a piezoelectric effect and converts mechanical energy into electrical energy, mainly made of materials such as barium titanate or zirconic acid. is made

In addition, the piezoelectric transducer 100 is electrically connected to the power generator 600, receives a preset amount of power from the power generator 600, and converts the supplied power into vibration.

Therefore, the piezoelectric transducer 100 is disposed on one side of the test piece S, that is, on the upper side of the test piece S, and generates mechanical vibration in the longitudinal direction (vertical direction) when power is applied by the power generator 600. let it

The amplifying horn 200 is configured to amplify the vibration generated by the piezoelectric transducer 100 and transmit it to the test piece S.

Specifically, the amplification horn 200 amplifies the vibration generated by the piezoelectric transducer 100 and transmits it to the test piece S, connecting the piezoelectric transducer 100 and the test piece S and using a resonance phenomenon Vibration generated by the piezoelectric transducer 100 may be amplified.

In general, since the vibration generated by the piezoelectric transducer 100 itself has a small amplitude, when the amplifying horn is omitted and the piezoelectric transducer 100 is directly connected to the test piece, the displacement of the size required for the fatigue test in the test piece S is difficult to occur For this reason, the amplification horn 200 is configured to be positioned between the piezoelectric transducer 100 and the test piece S, as shown in FIG.

In addition, the amplifying horn 200 according to the present invention includes the first amplifying horn 210 connecting the piezoelectric transducer 100 and one end of the test piece S, and the second amplifying horn 220 disposed at the other end of the test piece S. ) may be included.

The first amplifying horn 210 connects the piezoelectric transducer 100 and the test piece S to amplify the amplitude of vibration generated by the piezoelectric transducer 100 and transmit it to the test piece S.

In addition, since the first amplifying horn 210 amplifies the vibration generated in the piezoelectric transducer 100 by using the resonance phenomenon, the natural frequency (natural frequency) that can be resonated by the vibration of the piezoelectric transducer 100 The material, size and shape of the first amplifying horn 210 should be designed to In addition, the degree of amplifying the amplitude of the vibration generated from the piezoelectric transducer 100 of the first amplifying horn 210 varies depending on its material, size, and shape, which can generate a displacement of up to 50 μm in the test piece (S). It is desirable to select the material, size and shape so that

3 is a mechanism diagram for stress calibration of the ultrasonic fatigue test apparatus according to the present invention, and FIG. 6 is a diagram showing a program for setting stress ratio adjustment according to the present invention.

The second amplifying horn 220 is disposed at the other end of the test piece S, that is, at the lower end of the test piece S, and the upper end of the second amplifying horn 220 is coupled to the lower end of the test piece S, so that the test piece S ) so that the upper and lower ends of the first amplifying horn 210 and the second amplifying horn 220 can be maintained in a fixed state.

Therefore, in the ultrasonic fatigue test apparatus 1 according to the present invention, as shown in FIGS. 3 and 6, the tensile force preset by the driving module 400 is applied to the test piece S in a state in which both ends of the test piece S are fixed. ), it has the advantage that the stress ratio of the test piece (S) can be adjusted in various ways.

Stress Ratio represents the ratio between the minimum stress and maximum stress in a load cycle in a fatigue test. If the ultrasonic fatigue test is installed as a tensile-tensile test, the stress ratio R ratio can be adjusted in various ways, such as 0.1 or 0.01. there is.

In addition, the stress ratio R can be expressed as follows.

R =

는 응력의 최대치(최대응력),

는 응력의 최소치(최소응력))(

is the maximum value of stress (maximum stress),

is the minimum value of stress (minimum stress))

4 is a first graph showing the stress ratio and average stress control according to the present invention by way of example.

As shown in FIG. 4, the minimum stress is 10 MPa and the maximum stress is 100 MPa, and at this time, the stress ratio R = 10/100 = 0.1.

5 is a second graph exemplarily showing stress ratio and average stress control according to the present invention.

In addition, as shown in FIG. 5, after applying stress as much as the mean stress in the tensile-tensile test, the test is performed to obtain a maximum stress of 500 MPa, a minimum stress of 50 MPa, and an average stress ( Mean Stress) is 275 MPa.

At this time, the amplitude (Amplitude) appears as 225MPa.

8 is a graph showing the stress of a test piece in a fatigue test apparatus in which only one end of the test piece is installed as a fixed end.

If the test piece (S) mounted on the ultrasonic fatigue test device is in the form of a cantilever in which one end is fixed and the other end is free, as shown in FIG. 8, the stress ratio is -1 and the average stress (Mean Stress) appears as a value of 0, making various adjustments of the stress ratio impossible.

It can be seen that the displacement and strain generated in the longitudinal direction of the test piece (S) in the ultrasonic fatigue test apparatus 1 according to the present embodiment form a symmetrical waveform with respect to the center of the test piece (S). there is.

This is because the ultrasonic fatigue test apparatus 1 according to the present embodiment transmits vibration of the same waveform to both ends of the test piece S by a pair of amplification horns arranged symmetrically up and down around the test piece S. This is the result you can get.

Accordingly, the ultrasonic fatigue test apparatus 1 according to the present embodiment is a conventional fatigue test apparatus that transmits vibration only to one end of the test piece S by one piezoelectric transducer 100 and the amplification horn 200 ( In 1), the displacement and strain generated in the longitudinal direction of the test piece (S) do not form a symmetrical waveform with respect to the center of the test piece (S), so irregular fatigue stress is applied to the center of the test piece (S), which increases the reliability of the fatigue test. can solve the problem of dropping.

That is, the ultrasonic fatigue test apparatus 1 according to the present embodiment can improve the reliability of the fatigue test by applying a regular fatigue stress to the test piece S.

The displacement sensing unit 300 is configured to measure the displacement of the test piece S by detecting the amplitude and frequency of vibration generated in the test piece S by the vibration supplied from the piezoelectric transducer 100.

Specifically, the displacement sensing unit 300 detects the characteristics of vibration generated in the test piece S during the fatigue test, that is, the amplitude and frequency of the vibration, and the test piece S detected by the displacement sensing unit 300 The vibration characteristics of may be used as feedback data for controlling the power generator 600.

In addition, the displacement sensing unit 300 may include a strain gauge module 310 and a non-contact optical sensor module 320 .

The strain gauge module 310 is attached to one side of the test piece S and is provided to sense the strain of the test piece S, by simultaneously detecting the strain of the test piece S together with the non-contact optical sensor module 320. It is configured to apply regular fatigue stress to the test piece (S) by deriving the calibration stress of the test piece (S).

The non-contact optical sensor module 320 is disposed at a predetermined distance from one end of the test piece (S) and is provided to measure ultrasonic vibration of the test piece by sensing the projected irradiation light.

Specifically, the non-contact optical sensor module 320 is disposed at a predetermined interval at the other end, that is, the lower end of the test piece (S) to irradiate light toward the test piece (S), and the irradiated light is reflected by the test piece (S) It may be a module that detects and analyzes the vibration characteristics of the test piece (S).

Accordingly, the optical sensor module 320 may display the detected light intensity as a voltage level.

In addition, during the fatigue test, the test piece S vibrates at a predetermined amplitude and frequency, and appears in a form of vibrating while forming a waveform between the maximum voltage value and the minimum voltage value around the reference voltage value over time.

At this time, when the strain in which the length of the test piece is increased by the fatigue test occurs, the distance between the lower end of the test piece (S) and the optical sensor module 320 decreases. In this case, the displacement data output by the optical sensor module 320 is displayed in the form of a graph of the voltage level with time moving upward as a whole from the point of increase in the size of the test piece (S).

That is, the reference voltage value, the maximum voltage value, and the minimum voltage value from the point of increase in the size of the test piece (S) are set by the preset size for each of the reference voltage value, the maximum voltage value, and the minimum voltage value before the point of increase in the size of the test piece. has an added value.

Therefore, by analyzing the displacement data of the optical sensor module 320, the test piece size change of how much the length of the test piece (S) is increased can be grasped.

In addition, the test piece derived by calibrating the strain gauge value of the test piece S detected by the strain gauge module 310 of the displacement sensing unit 300 and the displacement value of the test piece S detected by the optical sensor module 320 ( The displacement data of S) is transmitted to the real-time control unit 500, and the control unit 500 receives real-time feedback from the displacement data so that the length of the test piece S is included in the preset reference range. size and frequency control.

The driving module 400 is provided to provide a predetermined tensile force to one side of the test piece (S) by moving the first amplifying horn 210 .

Specifically, the drive module 400 has a configuration for providing a tensile force upward to the test piece S with its lower end fixed, and is provided with a pair of hydraulic cylinders, and the pair of hydraulic cylinders have a first amplifying horn ( 210) is mounted on the support table 420, and the expandable cylinder rod 410 is coupled to the support table 420 on which the first amplifying horn 210 is mounted.

In addition, the cylinder rod 410 of the pair of hydraulic cylinders can move in the vertical direction along with the piezoelectric transducer 100 coupled to the first amplifying horn 210 by the extension operation.

Accordingly, the distance between the upper end and the lower end of the first amplifying horn 210 can be adjusted within a certain range by driving a pair of hydraulic cylinders.

As such, since the ultrasonic fatigue test apparatus 1 according to the present embodiment can apply a predetermined tensile force or compressive force to the mounted test piece S using the drive module 400 provided as a pair of hydraulic cylinders, the test piece It is possible to perform a fatigue test in a state in which an initial tensile or compressive force is applied to (S), so that the diversity of the fatigue test can be secured.

The control unit 500 receives real-time feedback on the displacement data output from the displacement sensing unit 300, and the size of power supplied to the piezoelectric transducer 100 so that the length of the test piece S is included in a predetermined reference range. configured to control the frequency.

In particular, the control unit 500 derives the calibrated displacement data of the test piece S by calibrating the displacement value measured by the strain gauge module 310 and the displacement value measured by the optical sensor module 320, and then the test piece It is configured to control the magnitude and frequency of power provided to the piezoelectric transducer 100 so that the length of (S) is included in a predetermined reference range.

In addition, the control unit 500 reflects the displacement value information measured by the displacement sensing unit 300 to calculate the Dynamic Young's modulus of the test piece (S), and uses the calculated dynamic Young's modulus It is configured to derive fatigue test results.

According to the ultrasonic fatigue test apparatus according to the present invention as described above, one end and the other end of the test piece are set as fixed ends, and a preset tensile force is applied to one end side, so that various stress ratios of the test piece can be adjusted and the strain of the test piece is measured It is configured to apply regular fatigue stress to the test piece by deriving the correction stress of the test piece, including a strain gauge module and an optical sensor module that is spaced apart and senses the irradiation light projected on the test piece, thereby improving the accuracy and reliability of the fatigue test. There are possible effects.

The terms and words used in this specification and claims described herein should not be construed as being limited to ordinary or dictionary meanings, and the present inventors appropriately use the concept of terms in order to explain their invention in the best way. It should be interpreted as a meaning and concept consistent with the technical idea of the present invention based on the principle that it can be defined.

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

1: Ultrasonic Fatigue Test Device
100: piezoelectric transducer 200: amplification horn
210: 1st amplification soul 220: 2nd amplification soul
300: displacement sensing unit 310: strain gauge module
320: non-contact optical sensor module 400: driving module
500: control unit 600: power generator

Claims (6)

A piezoelectric transducer disposed on one side of the test piece (Ultrasonic Transducer);
An amplification horn that amplifies vibration generated by the piezoelectric transducer and transfers it to the test piece, and includes a first amplification horn connecting the piezoelectric transducer and one end of the test piece and a second amplification horn disposed at the other end of the test piece;
a displacement sensing unit measuring the displacement of the test piece by detecting the amplitude and frequency of the vibration generated in the test piece by the vibration supplied from the piezoelectric transducer; and
A driving module for moving the first amplifying horn to provide a preset tensile force to one side of the test piece;
The displacement sensing unit,
a strain gauge module attached to one side of the test piece to sense the strain of the test piece; and
A non-contact optical sensor module disposed at a predetermined distance from one end of the test piece and measuring the ultrasonic vibration of the test piece by sensing the projected irradiation light;
A control unit for controlling the magnitude and frequency of power supplied to the piezoelectric transducer so that the length of the test piece is included in a preset reference range by receiving real-time feedback of the displacement data output by the displacement sensing unit;
The control unit,
After calibrating the displacement value measured by the strain gauge module and the displacement value measured by the optical sensor module to derive calibration displacement data of the test piece, the ultrasonic wave characterized in that for controlling the magnitude and frequency of power supplied to the piezoelectric transducer Fatigue test device.
According to claim 1,
The test piece,
The ultrasonic fatigue test apparatus, characterized in that the stress ratio of the test piece is adjusted by performing a fatigue test in a state where the other end is fixed by the second amplifying horn and a tensile force is applied to one end by the driving module.
delete delete delete According to claim 1,
The control unit,
Ultrasonic fatigue test apparatus, characterized in that for calculating the dynamic elastic modulus (Dynamic Young's modulus) of the test piece by reflecting the displacement value information measured by the displacement sensing unit, and deriving a fatigue test result using the calculated dynamic elastic modulus .

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