Young modulus tester and measuring method thereof

Abstract

The invention discloses a Young modulus tester and a measuring method thereof, and the Young modulus tester comprises a supporting column, a supporting seat, a beam expanding collimating mirror, a plane mirror, a first beam splitter, a second beam splitter, a CCD, an optical lever and a stretching platform, the supporting column forms a supporting frame, and the supporting seat is fixedly mounted on the supporting column; the beam expanding collimating mirror, the plane mirror, the first beam splitter, the second beam splitter, the CCD and the optical lever are all installed on the main platform, a notch is formed in the center of the main platform, and the stretching platform is installed at the notch. According to the basic principle of measuring the Young modulus, the tiny deformation amount of the metal wire is converted into the variation of the interference fringe interval through wedge interference, the elongation amount of the metal wire is obtained in real time through a digital image processing means, and therefore the Young modulus is calculated, and the measurement precision of the elongation amount can reach the submicron level. Each link deepens the previous link, the previous link plays a supporting role in the next link, data acquisition and data processing are carried out at the same time, and the data conversion efficiency is improved.

Description

Technical Field

[0001] The present application relates to the technical field of digital interferometry Young's modulus measurement, and in particular to a device for measuring Young's modulus using digital interferometry technology and a method for measuring the Young's modulus. Background Art

[0002] Traditional measurement devices for measuring Young's modulus usually require the use of complex test devices and a large amount of sample preparation, which is complicated and time-consuming to operate. In addition, traditional methods still have large errors and uncertainties, and cannot meet the needs of high-precision measurement. Some studies install a translation stage with a reading device at the scale of the traditional optical lever method Young's modulus tester, and measure the change in the distance from the optical lever plane reflector to the scale through the reading device of the translation stage. This can not only improve the convenience of experimental measurement, but also reduce the random error of measurement through multiple measurements under the same experimental conditions. Another improvement method is to use a laser instead of a telescope to obtain the reading on the measuring scale. This method is easy to adjust, intuitive, and accurate. However, these devices often have no effect on small changes and even their own performance is affected and reduced. After searching, no literature of this type has been found. Summary of the invention

[0003] The purpose of the present application is to provide a Young's modulus measuring instrument and a measuring method thereof, which can achieve high-precision measurement of Young's modulus through simple operation.

[0004] The purpose of this application is achieved by the following technical solutions: In one aspect, the present application provides a Young's modulus measuring instrument, comprising: An upper platform, wherein the upper platform is processed with three guide mounting holes at fixed angles; A support column, wherein the support column is connected to the upper platform to form a support frame for supporting the measuring instrument; The main platform, the working platform of the Young's modulus tester, is used to install all optical measurement systems; A support seat, the support seat is fixedly mounted on the support column and is used to support the main platform; A beam expander and collimator lens, which is mounted on the main platform and is used to expand and collimate the light beam; A semiconductor laser, which is mounted on the main platform and arranged behind the beam expander collimator to provide a coherent light source for the measuring instrument; A plane reflector, the plane reflector is mounted on the main platform and is used to reflect light onto the first beam splitter; a first beam splitter, the first beam splitter being mounted on the main platform and configured to reflect light onto a second beam splitter in the wedge tip; A second beam splitter, which is mounted on the main platform and arranged in front of the optical lever to form a wedge-shaped structure with the optical lever. The second beam splitter is used to split the incident light into two beams, wherein the reflected light is used as a reference light; An optical lever, which is mounted on the main platform and arranged behind the second beam splitter, and forms a wedge-tip structure with the second beam splitter, and is used to receive the transmitted light and then reflect it onto the CCD as object light, and the two beams of light together generate interference fringes on the CCD; CCD, the CCD is mounted on the main platform and is used to record interference fringes; The stretching platform has a notch at the center of the main platform, and the stretching platform is installed at the notch through a linear square rail.

[0005] On the other hand, the present application also provides a measurement method of a Young's modulus measuring instrument, characterized in that it comprises the following steps: 1) Place the level on the main platform and adjust the position of the support seat to make the main platform level; 2) Fix one end of the metal wire with measured length and diameter through the metal chuck on the upper platform of the device, and fix the other end through the metal chuck on the lower platform. At this time, the metal wire can be hung vertically in the center of the device; 3) The laser emitted by the semiconductor laser is emitted as a beam of parallel light after passing through the beam expander and collimator. The parallel light is emitted to the first beam splitter through the plane reflector, and then irradiates the wedge-shaped measurement system after being reflected by the first beam splitter. 4) The wedge-type measurement system consists of a second beam splitter with a transmission-reflection ratio of 6:4 and an optical lever. The second beam splitter splits the incident light into two beams, of which the reflected light is directly irradiated onto the CCD recording surface as the reference light R; the transmitted light is reflected by the plane reflector onto the CCD as the object light O and generates equal-thickness interference with the reference light R; 5) Use the real-time image acquisition and processing system written on the Raspberry Pi to obtain the interference fringe image through the CCD camera. Adjust the plane reflector so that the interference fringe direction recorded by the CCD is horizontal; 6) Click the "Start Calibration" button on the program interface on the Raspberry Pi, then adjust the fine-tuning bolt on the optical lever so that the number of initial interference fringes is around 100, and then click the "End Calibration" button; 7) Mount a 50g weight, enter the "length", "diameter" and "weight mass" on the software interface, click the "start measurement" button, and the software will output the "elongation" and "Young's modulus" of the wire in real time; 8) Change the mass of the weights and perform multiple measurements.

[0006] Compared with the prior art, the beneficial effects of this application include at least: (1) The present application can achieve high-precision measurement of Young's modulus through simple operation. At the same time, the device should have the characteristics of high reliability, good repeatability, and easy operation to meet the needs of scientific research and engineering applications.

[0007] (2) This application adopts the method of converting the tiny deformation of the sample to be measured into the change of the interference fringe spacing through a self-made measurement system for high-precision collection and calculation. The measurement accuracy can reach sub-micron level; each link is a deepening of the previous link, and the previous link plays a supporting role for the next link. The data collection and processing processes and stages are carried out simultaneously to improve the data conversion efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 is a schematic diagram of the overall structure of the measuring instrument in the embodiment of the present application; Figure 2 yes Figure 3 A magnified view of a part in the middle; Figure 3 It is a structural schematic diagram of the upper platform of an embodiment of the present application; Figure 4 is a schematic diagram of the structure of an optical lever according to an embodiment of the present application; Figure 5 This is a schematic diagram of the structure of the support base of the embodiment of the present application. Figure 1 ; Figure 6 This is a schematic diagram of the structure of the pole support seat in the embodiment of the present application. Figure 2 ; Figure 7 This is the Raspberry Pi GUI application interface diagram of this application; Figure 8 This is a flow chart of Young's modulus measurement for this application; Fig. 9 This is the principle diagram of the optical path for measuring Young's modulus using wedge-tip interferometry in this application; Fig.10 This is the schematic diagram of the optical lever of this application. DETAILED DESCRIPTION

[0009] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in a variety of forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided to make this application more comprehensive and complete and to fully convey the concepts of example embodiments to those skilled in the art. The same reference numerals in the figures represent the same or similar structures, and thus their repeated description will be omitted.

[0010] The words expressing position and direction described in this application are all explained with reference to the accompanying drawings as examples, but they can be changed as needed, and all changes are included in the scope of protection of this application.

[0011] like Figures 1 to 9 As shown, a Young's modulus measuring instrument corresponding to an embodiment of the present application includes: a support column 1, a support seat 3, a beam expander collimator 21, a plane reflector 22, a first beam splitter 25, a second beam splitter 26, a CCD 23, an optical lever 27, a stretching platform 28 and a semiconductor laser 6. The support columns 1 of the present application are several and can form a support frame for supporting the measuring instrument. Preferably, the number of support columns 1 of the present application is three; the support seat 3 of the present application is fixedly mounted on the support column. Specifically, the support seat 3 of the present application can be fixedly mounted on the support column by screws and is used to support the main platform; the beam expander collimator 21 of the present application is mounted on the main platform 2 for expanding the laser beam; the semiconductor laser 6 of the present application is mounted on the main platform 2 and is arranged behind the beam expander collimator 21 for providing a coherent light source for the measuring instrument; the plane reflector 22 of the present application is mounted on the main platform 2 for The light is reflected onto the first beam splitter 25; the first beam splitter 25 of the present application is installed on the main platform 2, and is used to reflect the light to the second beam splitter 26 in the wedge portion; the second beam splitter 26 of the present application is installed on the main platform 2 and is arranged in front of the optical lever 27, and forms a wedge structure with the optical lever 27. The second beam splitter 26 is used to split the incident light into two beams, wherein the reflected light is used as the reference light; the optical lever 27 of the present application is installed on the main platform 2 and is arranged behind the second beam splitter 26, and forms a wedge structure with the second beam splitter 26, and is used to receive the transmitted light and then reflect it onto the CCD23 as the object light, and the two beams of light jointly generate interference fringes on the CCD23; the CCD23 is installed on the main platform 2, and is used to record the interference fringes; a notch 29 is provided on the main platform 2 of the present application, and the stretching platform 28 is installed at the notch 29. The shape of the main platform 2 of the present application can be determined according to the number of support columns 1.

[0012] like Figure 1 , Figure 2 , Figure 7 and Figure 8 As shown, as the preferred technical solution of the previous step, the measuring instrument of the present application also includes a Raspberry Pi 24, which is installed on the main platform 2 and is used to obtain the interference fringes collected on the CCD 23 in real time, and digitally process and calculate the fringes image through a visual interactive interface program. The software algorithm part of the entire system is based on the Python programming language as a platform and is built on the Linux system of the Raspberry Pi. Python, as an object-oriented programming language, can easily realize the image reading, numerical processing and graphic interaction functions of the CCD camera by calling library functions.

[0013] like Figure 1 and Figure 2As shown, as the preferred technical solution in the previous step, the support columns 1 of the present application are three, and the upper ends of the three support columns 1 are connected through the upper platform 4. The upper platform 4 is provided with three guide mounting holes 41, and the guide mounting holes 41 match the upper ends of the support columns 1. The support columns 1 of the present application can also be four, and the upper ends of the four support columns 1 are connected through the upper platform 4, and the four support columns 1 form a four-frame structure.

[0014] like Figure 4 As shown, as the preferred technical solution in the previous step, the optical lever 27 of the present application includes a connecting seat 274, wherein the lower end of the connecting seat 274 is mounted on the main platform 2, and specifically, the lower end of the connecting seat 274 can be mounted on the main platform 2 by screws, and the upper end of the connecting seat 274 is rotatably connected to a plane reflector 271. A support arm 272 is connected to one side of the plane reflector 271 of the present application, and the support arm 272 can rotate with the plane reflector 271. A fine-tuning bolt 273 is connected to the end of the support arm 272, and the fine-tuning bolt 273 can accurately adjust the pitch angle of the plane reflector 271 and can rotate with the support arm 272.

[0015] like Figure 5 and Figure 6 As shown, as the preferred technical solution of the previous step, the support seat 3 of the present application includes a support portion 31 and a connecting portion 32, wherein the support portion 31 and the connecting portion 32 are integrally formed and connected, the support portion 31 is used to support the main platform 2, and the connecting portion 32 is used to be connected and fixed on the support column 3, and the height is adjustable. Among them, a round through hole 321 is provided on the connecting portion 32, and the round through hole 321 cooperates with the support column 1, and a screw hole 322 is also provided on the connecting portion 32, and the screw hole 322 is connected to the round through hole 321, and a long through hole 311 is provided on the supporting portion 31, and the long through hole 311 cooperates with the main platform 2.

[0016] like Figure 1 and Figure 2 As shown, as the preferred technical solution of the previous step, an adjustable chuck is provided on the stretching platform 2, and the upper platform 4 is provided with an adjustable chuck 42, and the material 5 to be tested is clamped between the adjustable chuck on the stretching platform 2 and the adjustable chuck 42 on the upper platform 4.

[0017] In this application, the material to be tested 5 is a metal wire. One end of the metal wire with measured length l0 and diameter d is fixed by the metal chuck on the upper platform of the device, and the other end is fixed by the metal chuck on the lower platform. At this time, the metal wire can be vertically hung in the center of the device. Among them, Young's modulus E can be expressed as (1) The laser emitted by the semiconductor laser 6 (wavelength 650 nm) is emitted as a beam of parallel light after passing through the beam expander collimator 21. The parallel light is emitted to the beam splitter 25 through the plane reflector 22, and then irradiates the wedge-shaped measurement system after being reflected by the beam splitter 25. The wedge-shaped measurement system is composed of a beam splitter 26 and a self-made optical lever 27 (a plane reflector is attached to the vertical surface of the optical lever 27). The beam splitter 26 splits the incident light into two beams, of which the reflected light is directly irradiated onto the recording surface of CCD23 as the reference light R; the transmitted light is reflected by the plane reflector 271 onto CCD23 as the object light O, which interferes with the reference light R with equal thickness. The optical path is as follows: Fig. 9 shown.

[0018] like Fig.10 The figure shows the principle diagram of the optical lever. When the metal wire is slightly extended under the gravity of the weight, the left leg of the optical lever begins to descend along with the table. The distance the table moves up and down is the extension of the metal wire. . Assume the length of the optical lever is The extension of the wire can be measured by the optical lever. Converted into the angle change of the plane reflector , from the geometric relationship we can get (2) (1) Before loading, the width of adjacent stripes It can be obtained from the geometric relationship of the wedge tip and the distribution conditions of the interference fringes (3) (2) After the weight is loaded and the wire is stretched, the angle between the optical lever mirror and the beam splitter increases. , that is, the wedge angle increases , the width of adjacent stripes for: (4) Substituting equations (2)-(4) into equation (1), the Young's modulus of the metal wire can be calculated as: (5) The image processing process uses filtering + curve fitting method to obtain the stripe width value with sub-pixel accuracy. The specific steps are as follows: (1) Frequency domain filtering. The acquired digital interference image contains a lot of noise, so filtering is required first. The interference pattern is transformed into the frequency domain through DFFT2 discrete two-dimensional Fourier transform, and a suitable window filter function is set to perform bandpass filtering on the +1 level spectrum. Then the spectrum is transformed into the spatial domain through IDFFT2 discrete two-dimensional inverse Fourier transform to obtain the interference fringe image after noise reduction.

[0019] (2) Curve fitting: In order to obtain the width of the sub-pixel interference fringes, a curve fitting method is used to obtain the fringe frequency f on the CCD window. It is known that the interference fringes are sinusoidal fringes, and the fitting function can be defined as: (6) Where x is the pixel coordinate, y is the intensity distribution of the fringe, a is the amplitude, and b is the initial phase. The fringe frequency f on the CCD window can be obtained by calling the CurveFit library function. The pixel size of the CCD camera is , the pixel size is μm, so the width of adjacent interference fringes can be obtained for (7) The above process is carried out through Figure 7 The visual graphical interface written on the Raspberry Pi as shown in the figure realizes the control of the measurement and the real-time display of the measurement results. The specific measurement process is as follows Figure 8 As shown: (1) Place a level on the main platform and adjust the position of the support base 31 to make the main platform 2 level; (2) Fix one end of the metal wire whose length and diameter have been measured through the metal chuck on the upper platform of the device, and fix the other end through the metal chuck on the lower platform. At this time, the metal wire can be hung vertically in the center of the device; (3) Turn on the semiconductor laser, click the "Start Calibration" button on the program interface, observe the interference fringe image through the "Real-time Acquisition Fringe Image Window", and adjust the beam expander collimator 21, plane reflector 22 and beam splitter 26 so that the interference fringes are distributed in the horizontal direction; (4) Adjust the fine-tuning bolt 273 on the optical lever 27 so that the number of initial interference fringes is about 100. After the number of fringes stabilizes, click the "End Calibration" button; (5) Mount the weight and enter the parameters of "length", "diameter" and "weight" on the software interface; (6) Click the "Start Measurement" button, and the software will output the "elongation" and "Young's modulus" of the metal wire in real time; (7) Change the mass of the weight and repeat the measurement.

[0020] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in the field can change, modify, replace and modify the above embodiments within the scope of the application without departing from the principles and purpose of the present application. All of these changes should fall within the scope of protection of the claims of the present application.

Claims

1. A Young's modulus measuring instrument, characterized in that: include: An upper platform, wherein the upper platform is processed with three guide mounting holes at fixed angles; A support column, wherein the support column is connected to the upper platform to form a support frame for supporting the measuring instrument; The main platform, the working platform of the Young's modulus tester, is used to install all optical measurement systems; A support seat, the support seat is fixedly mounted on the support column and is used to support the main platform; A beam expander and collimator lens, which is mounted on the main platform and is used to expand and collimate the light beam; A semiconductor laser, which is mounted on the main platform and arranged behind the beam expander collimator to provide a coherent light source for the measuring instrument; A plane reflector, the plane reflector is mounted on the main platform and is used to reflect light onto the first beam splitter; a first beam splitter, the first beam splitter being mounted on the main platform and configured to reflect light onto a second beam splitter in the wedge tip; A second beam splitter, which is mounted on the main platform and arranged in front of the optical lever to form a wedge-shaped structure with the optical lever. The second beam splitter is used to split the incident light into two beams, wherein the reflected light is used as a reference light; An optical lever, which is mounted on the main platform and arranged behind the second beam splitter, and forms a wedge-tip structure with the second beam splitter, and is used to receive the transmitted light and then reflect it onto the CCD as object light, and the two beams of light together generate interference fringes on the CCD; CCD, the CCD is mounted on the main platform and is used to record interference fringes; The stretching platform has a notch at the center of the main platform, and the stretching platform is installed at the notch through a linear square rail.

2. A Young's modulus measuring instrument according to claim 1, characterized in that: The measuring instrument also includes a Raspberry Pi, which is installed on the main platform and is used to carry the software part of the measurement system and obtain the interference fringes on the CCD and perform digital processing on the measurement in a pre-edited visual interactive interface program.

3. A Young's modulus measuring instrument according to claim 1, characterized in that: There are three support columns, the upper ends of the three support columns are connected through an upper platform, and the guide mounting holes arranged on the upper platform are matched with the upper ends of the support columns.

4. A Young's modulus measuring instrument according to claim 1, characterized in that: The optical lever comprises a connecting seat, the lower end of which is mounted on the main platform, and the upper end of which is rotatably connected to a plane reflecting mirror.

5. The optical lever according to claim 4, characterized in that: A plane reflector is attached to one side of the vertical mounting surface of the optical lever, and a support arm is connected to the other side. A fine-tuning bolt is connected to the end of the support arm. The optical lever is mounted on the connecting seat through a bearing.

6. A Young's modulus measuring instrument according to claim 1, characterized in that: The support seat includes a support portion and a connection portion, and the support portion and the connection portion are connected by an integrally formed design. The support portion is used to support the main platform, and the connection portion is used to be connected and fixed on the support column.

7. A Young's modulus measuring instrument according to claim 6, characterized in that: The connecting part is provided with a round through hole, which cooperates with the supporting column. The connecting part is also provided with a screw hole, which is connected with the round through hole. The supporting part is provided with a long through hole, which cooperates with the main platform.

8. A Young's modulus measuring instrument according to claim 1, characterized in that: The stretching platform is provided with an adjustable chuck, the upper platform is provided with an adjustable chuck, and the sample to be tested is clamped between the upper and lower adjustable chucks.

9. A method for measuring a Young's modulus tester, characterized in that: The steps include: 1) Place the level on the main platform and adjust the position of the support seat to make the main platform level; 2) Fix one end of the metal wire with measured length and diameter through the metal chuck on the upper platform of the device, and fix the other end through the metal chuck on the lower platform. At this time, the metal wire can be hung vertically in the center of the device; 3) The laser emitted by the semiconductor laser is emitted as a beam of parallel light after passing through the beam expander and collimator. The parallel light is emitted to the first beam splitter through the plane reflector, and then irradiates the wedge-shaped measurement system after being reflected by the first beam splitter. 4) The wedge-type measurement system consists of a second beam splitter with a transmission-reflection ratio of 6:4 and an optical lever. The second beam splitter splits the incident light into two beams, of which the reflected light is directly irradiated onto the CCD recording surface as the reference light R; the transmitted light is reflected by the plane reflector onto the CCD as the object light O and generates equal-thickness interference with the reference light R; 5) Use the real-time image acquisition and processing system written on the Raspberry Pi to obtain the interference fringe image through the CCD camera. Adjust the plane reflector so that the interference fringe direction recorded by the CCD is horizontal; 6) Click the "Start Calibration" button on the program interface on the Raspberry Pi, then adjust the fine-tuning bolt on the optical lever so that the number of initial interference fringes is around 100, and then click the "End Calibration" button; 7) Mount a 50g weight, enter "length", "diameter" and "weight mass" on the software interface, click the "start measurement" button, and the software will output the "elongation" and "Young's modulus" of the wire in real time; 8) Change the mass of the weights and perform multiple measurements.

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