Young modulus measuring method and system for experiment teaching

Abstract

The invention discloses a Young modulus measuring method and a Young modulus measuring system for experiment teaching. An optical magnification lens group and a camera are sequentially arranged in the front edge optical axis direction of a fixed column at the bottom end of a test sample, an image of the fixed column is collected, and the positions of scale lines of a reticle and mark lines on the fixed column are recognized through a horizontal projection peak detection algorithm and an image processing algorithm of a multi-line equidistant recognition algorithm. High-precision automatic measurement of shrinkage and elongation of the test sample is realized; the AI tutoring module automatically judges whether an operation error exists or not according to the acknowledged value; the problems of low measurement precision, insufficient guidance, low efficiency and the like in a traditional physical experiment are solved, and the experiment teaching quality is remarkably improved; the device is suitable for experiment teaching of Young modulus measurement in university physical experiments, and can be expanded and applied to industrial or scientific research scenes of material mechanical property testing.

Description

Technical Field

[0001] This invention relates to physics experimental teaching equipment, specifically to a method and system for measuring Young's modulus in experimental teaching. Background Technology

[0002] Young's modulus, also known as the elastic modulus, is a physical quantity that characterizes the ability of a solid material to resist deformation. It is defined as the ratio of stress to strain when the material is under uniaxial tension or compression. Young's modulus is an indispensable key parameter in materials design and structural analysis, and is widely used in civil engineering, mechanical manufacturing, aerospace and other fields.

[0003] Various experimental methods can be used to measure Young's modulus, among which the tensile method is a commonly used laboratory measurement method due to its simple principle, convenient operation, and intuitive results. The tensile method involves applying an axial tensile force to a material sample of a specific geometry and measuring its elongation under the tensile force. By combining the original length, cross-sectional area, and applied tensile force of the sample, Young's modulus can be calculated.

[0004] Traditional tensile testing typically uses contact measuring tools such as micrometers and steel rulers, with the elongation of the sample read manually. This method has the following drawbacks: Limited accuracy: Manual readings are easily affected by subjective factors, and the precision limitations of the measuring tools themselves lead to significant measurement errors. Low efficiency: Point-by-point measurements are time-consuming and labor-intensive, making it difficult to achieve rapid batch measurements.

[0005] In recent years, with the development of image processing and machine vision technologies, non-contact measurement methods have been increasingly applied to the measurement of Young's modulus. For example, the digital image correlation (DIC) method calculates the strain distribution of a sample by analyzing the changes in its surface image before and after deformation, thereby determining Young's modulus. However, the DIC method requires high image quality, and the calculation process is complex and relatively expensive.

[0006] Therefore, developing a high-precision, high-efficiency, and low-cost method for measuring Young's modulus is of significant practical importance. In particular, how to utilize existing experimental equipment and combine it with image processing technology to achieve accurate measurement of Young's modulus is currently one of the hot research topics.

[0007] At the same time, when conducting experiments related to Young's modulus, due to the large number of experimenters, it is often difficult to get timely and professional answers from teachers when encountering problems and needing to consult them.

[0008] In recent years, with the development of artificial intelligence, the application of various large AI models and the introduction of targeted knowledge bases have made AI model answers more professional. Correctly using AI models to provide real-time monitoring and guidance to experimenters during the experimental process is also one of the current research hotspots. Summary of the Invention

[0009] To address the problems existing in the prior art, this invention proposes a method and system for measuring Young's modulus in experimental teaching. By integrating image processing, data analysis, and intelligent tutoring functions, it solves the problems of cumbersome manual operation, large errors, and insufficient guidance in traditional experiments. Through this measurement system, students can master the method for measuring Young's modulus.

[0010] The existing Young's modulus measurement system for experimental teaching includes: a Young's modulus rod, a fixed column, and weights. The test sample is placed on the Young's modulus rod, with its end fixed to the top of the fixed column. Weights are placed at the bottom of the fixed column, and the test sample is stretched by the weights. Different masses of weights result in different stretches of the test sample. Horizontal marking lines are set on the fixed column, and the position of the marking lines changes with the length of the test sample. That is, the change in the position of the marking lines represents the change in the length of the test sample. The Young's modulus of the test sample is obtained by observing the change in the position of the marking lines.

[0011] One object of the present invention is to provide a Young's modulus measurement system for experimental teaching.

[0012] The Young's modulus measurement system for experimental teaching of the present invention includes: an optical magnifying lens assembly, a camera, a video capture card, and a computer; wherein, a reticle located in a vertical plane is set in the optical magnifying lens assembly, the reticle is made of light-transmitting material, and the reticle has multiple equally spaced scale lines along the horizontal direction; a fixed post, the optical magnifying lens assembly, and the camera are arranged sequentially along the optical axis; the camera is connected to the computer via the video capture card; before measurement, the scale lines of the reticle are calibrated, a white board is placed between the optical magnifying lens assembly and the fixed post to remove the background image of the fixed post, so that the camera only captures the image of the reticle, the image of the reticle captured by the camera is transmitted to the computer, and the position of the scale lines is automatically identified and the scale line is obtained through a horizontal projection peak detection algorithm combined with a multi-line equidistant recognition algorithm. The magnification factor between the graduation lines; the white board is removed, and a weight is placed at the bottom of the test sample. The test sample is stretched by the weight, and the position of the marking line on the fixed column changes accordingly; the image of the fixed column surface is magnified by an optical magnifying lens group, and the images of the graduation lines of the reticle and the marking lines on the fixed column are captured by a camera and transmitted to a video capture card, and then transmitted to a computer; the computer automatically identifies the position of the graduation lines of the reticle and the marking lines on the fixed column through a horizontal projection peak detection algorithm; the mass of the weight is changed, and multiple sets of measurements are performed. Based on the positional change of the marking line relative to the graduation line and combined with the magnification factor between the graduation lines, the shrinkage or elongation of the test sample is calculated, realizing the identification of shrinkage and elongation through computer vision, and the Young's modulus of the test sample is calculated by the method of successive differences.

[0013] Another objective of this invention is to propose a method for measuring Young's modulus for experimental teaching.

[0014] The method for measuring Young's modulus for experimental teaching of the present invention includes the following steps:

[0015] 1) Set up the measuring device:

[0016] A reticle is set in the optical magnifying lens assembly, located on the vertical plane. The reticle is made of light-transmitting material and has multiple scale lines that are equally spaced along the horizontal direction.

[0017] A fixed post, an optical magnifying lens group, and a camera are sequentially arranged along the optical axis; the camera is connected to a computer via a video capture card.

[0018] 2) Determine the position of the graduation lines on the reticle:

[0019] Before measurement, a whiteboard is placed between the optical magnifying lens group and the fixed post to remove the background image of the fixed post, so that the camera only captures the image of the reticle; the image of the reticle captured by the camera is transmitted to the computer, and the position of the scale lines is automatically identified by the horizontal projection peak detection algorithm combined with the multi-line equidistant recognition algorithm, and the magnification ratio coefficient between the scale lines is obtained; the whiteboard is then removed.

[0020] 3) Measure Young's modulus:

[0021] a) A weight is placed at the bottom of the test sample. The test sample is stretched or compressed as the weight is increased or decreased, and the position of the marking line on the fixed column changes accordingly.

[0022] b) After the image on the surface of the fixed column is magnified by the optical magnifying lens group, the images of the scale lines of the reticle and the marking lines on the fixed column are captured by the camera and transmitted to the video capture card and then to the computer;

[0023] c) The computer automatically identifies the positions of the scale lines on the reticle and the marking lines on the fixed post through a horizontal projection peak detection algorithm to achieve automatic detection of feature lines;

[0024] d) Use real-time position tracking technology based on multi-frame analysis to perform dynamic stability detection and determine whether the position of the marker line is stable. If the position of the marker line is unstable, return to step b). If the position of the marker line is stable, it indicates that the stretching or compression process has ended and proceed to the next step.

[0025] e) The position of the marking line is transmitted to the AI ​​tutoring module. The AI ​​tutoring module judges whether the elongation or shrinkage of the test sample is reasonable based on the accepted value. If it is too large or too small, there is an operation error. Data with operation errors is not recorded. The module analyzes the operation errors corresponding to the excessive or insufficient values ​​based on the knowledge base and provides corresponding modification suggestions.

[0026] f) Change the mass of the weights and repeat steps a) to e) to perform multiple sets of measurements and obtain multiple sets of measurement data;

[0027] g) Based on the positional change of the marking line relative to the scale line, and combined with the magnification ratio coefficient between the scale lines, the elongation or shrinkage of the test sample is calculated, so as to realize the identification of elongation and shrinkage through computer vision, and the Young's modulus of the test sample is calculated by the method of successive differences.

[0028] The method of automatically identifying the position of candidate tick marks or marker lines using the horizontal projection peak detection algorithm includes the following steps: i. converting the image to grayscale, so that each pixel obtains a corresponding grayscale value;

[0029] ii. Overlay the grayscale values ​​of each row, where a row refers to the horizontal coordinate, to obtain the row grayscale values;

[0030] iii. Based on the row grayscale values, find the peak grayscale value;

[0031] When identifying the scale lines on the reticle, since the scale lines are black, they are dark areas in the grayscale image and are easily confused with dirt, noise, and shadows. There are also cases where multiple scale lines are mixed with other interfering lines (dirt, noise, or shadows). The position of the grayscale peak value is used as the location of the candidate scale line.

[0032] Alternatively, when identifying the marker line, the marker line has a strong contrast with the background, and it is a single target, meaning there is only one marker line in the field of view.

[0033] There's no need to distinguish between multiple lines; simply find the peak value of the maximum grayscale value to determine the location of the marker line.

[0034] In step 2), multiple candidate tick marks are identified by the horizontal projection peak detection algorithm. A multi-line equidistant recognition algorithm is then used to identify multiple lines with equal spacing between adjacent candidate tick marks as tick marks. The ratio of the distance between tick marks on the image to the actual distance between tick marks is automatically calibrated to obtain the magnification ratio between tick marks. Feature lines include tick marks and marker lines.

[0035] In step 3) d), dynamic stability detection is performed using real-time position tracking technology based on multi-frame analysis: images of the marker line are acquired frame by frame, and the position of the marker line is compared frame by frame. If the position change of the marker line is less than the threshold (1 pixel to 3 pixels) for multiple consecutive frames (30 to 80 frames), it indicates that the elongation or contraction has stabilized.

[0036] In step 3)e), the AI ​​tutoring module includes: laboratory tensile method for measuring Young's modulus, supporting DOCX / TXT file import and semantic retrieval; a pre-test system, including multiple-choice question bank, fill-in-the-blank question bank and thinking question bank; a real-time Q&A engine that generates professional answers by combining knowledge base context; and intelligent analysis of experimental reports, supporting OCR recognition and data integrity verification.

[0037] Advantages of this invention:

[0038] This invention achieves high-precision automatic measurement through an image processing algorithm that combines a horizontal projection peak detection algorithm with a multi-line equidistant recognition algorithm; the AI ​​tutoring module provides real-time guidance based on knowledge graphs and semantic retrieval; this invention solves the problems of low measurement accuracy, insufficient guidance, and low efficiency in traditional physics experiments, and significantly improves the quality of experimental teaching; it is suitable for experimental teaching of Young's modulus measurement in university physics experiments, and can be extended to industrial or scientific research scenarios for material mechanical property testing. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of one embodiment of the Young's modulus measurement system for experimental teaching according to the present invention.

[0040] Figure 2 This is a front view of a fixed column according to an embodiment of the Young's modulus measurement system for experimental teaching of the present invention;

[0041] Figure 3 This is a schematic diagram of an optical magnifying lens assembly. Detailed Implementation

[0042] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0043] The method for measuring Young's modulus for experimental teaching in this embodiment includes the following steps:

[0044] 1) Set up a measuring device, such as Figure 1 As shown:

[0045] The test sample is an adjustable-length metal wire with a diameter of 0.2-0.5 mm and a length of 0.8-1.2 m. The wire is mounted on a Young's modulus rod, with its end fixed to the top of a fixed post. Screws on both sides of the fixed post restrict its movement. A weight tray is placed at the bottom of the fixed post, and weights are placed on the tray. Figure 2 As shown;

[0046] A light-transmitting reticle is placed vertically between the eyepiece and objective lens of the optical magnifying lens assembly, such as... Figure 3 As shown,

[0047] The reticle has three equally spaced black graduation lines along the horizontal direction;

[0048] A fixed column, an optical magnifying lens group, and a camera are sequentially arranged along the optical axis; the camera is connected to a computer via a video capture card; the camera is a CCD camera and is connected to an external DC 12V power supply.

[0049] 2) Determine the position of the graduation lines on the reticle:

[0050] Before measurement, a whiteboard is placed between the optical magnifying lens group and the fixed post to remove the background image of the fixed post, so that the camera can only capture the image of the reticle. The image of the reticle captured by the camera is transmitted to the computer, and the position of the scale lines of the reticle is automatically identified by the horizontal projection peak detection algorithm combined with the multi-line equidistant recognition algorithm, and the magnification ratio coefficient between the scale lines is obtained.

[0051] Among them, when identifying the scale lines of the reticle through the horizontal projection peak detection algorithm, multiple candidate scale lines will be identified: i. The image is converted to grayscale, and each pixel obtains the corresponding grayscale value;

[0052] ii. Overlay the grayscale values ​​of each row, where a row refers to the horizontal coordinate, to obtain the row grayscale values;

[0053] iii. Since the tick marks are black, they are dark areas in the grayscale image and are easily confused with blemishes, noise, and shadows. There are also cases where multiple tick marks are mixed with other interfering lines (blemishes, noise, or shadows). Based on the row grayscale values, find the peak grayscale value and use the position of the peak grayscale value as the position of the candidate tick mark.

[0054] A multi-line equidistant recognition algorithm is used:

[0055] Identify multiple lines with equal spacing between two adjacent candidate scale lines as scale lines, and automatically calibrate the ratio coefficient between the distance between scale lines on the image and the actual distance between scale lines to obtain the magnification ratio coefficient between scale lines; remove the whiteboard;

[0056] 3) Measure Young's modulus:

[0057] a) A weight is placed at the bottom of the metal wire. The metal wire is stretched or compressed as the weight is increased or decreased, and the position of the marking line on the fixed post changes accordingly.

[0058] b) After the image on the surface of the fixed column is magnified by the optical magnifying lens group, the images of the scale lines of the reticle and the marking lines on the fixed column are captured by the camera and transmitted to the video capture card and then to the computer;

[0059] c) The contrast between the marker line and the background is strong, and it is a single target, that is, there is only one marker line in the field of view. The computer automatically identifies the peak value of the maximum gray value through the horizontal projection peak detection algorithm, which is the location of the marker line. The computer also automatically identifies the location of the scale line of the reticle through the horizontal projection peak detection algorithm, thus realizing automatic detection of feature lines.

[0060] d) Dynamic stability detection is performed using real-time position tracking technology based on multi-frame analysis: the image of the marker line is acquired frame by frame, one frame is acquired every 0.1s, and the position of the marker line is compared frame by frame. If the position change of the marker line is less than 1 pixel for 60 consecutive frames, it indicates that the elongation or contraction has stabilized. If the position of the marker line is unstable, return to step b). If the position of the marker line is stable, it indicates that the stretching process has ended and proceed to the next step.

[0061] e) The position of the marking line is transmitted to the AI ​​tutoring module. The AI ​​tutoring module judges whether the elongation or shrinkage of the metal wire is reasonable based on the accepted value of Young's modulus of 200 GPa. If it is too large or too small, there is an operation error. Data with operation errors is not recorded. The module analyzes the corresponding operation errors of too large or too small based on the knowledge base and gives corresponding modification suggestions.

[0062] f) Change the mass of the weights and repeat steps a) to e) to perform 20 sets of measurements, adding / removing weights 10 times each, to obtain 10 sets of measurement data.

[0063] g) Based on the positional change of the marking line relative to the scale line, and combined with the magnification ratio coefficient between the scale lines, the shrinkage or elongation of the metal wire is calculated. The shrinkage and elongation are identified by computer vision, and the Young's modulus of the metal wire is calculated by the method of successive differences. The standard deviation of the diameter measurement is automatically calculated by AI-assisted analysis for error analysis. The relative error between the measured value and the accepted value is compared to verify the results. After the measurement is completed, an experimental record sheet is automatically generated.

[0064] The invention has significant advantages: measurement efficiency is increased by 6 times (traditional experiment 120min → this invention 20min); key parameter errors are reduced: diameter measurement fluctuation ≤0.002mm, elongation error <0.01mm; report generation time is reduced from 60min to instant automatic generation.

[0065] Finally, it should be noted that the purpose of disclosing the embodiments is to help further understand the present invention. However, those skilled in the art will understand that various substitutions and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the present invention should not be limited to the content disclosed in the embodiments, and the scope of protection of the present invention is defined by the claims.

Claims

1. A method for measuring Young's modulus in experimental teaching, characterized in that, The measurement method includes the following steps: 1) Set up the measuring device: A reticle located on a vertical plane is set in the optical magnifying lens assembly. The reticle has multiple scale lines that are equally spaced along the horizontal direction. A fixed post, an optical magnifying lens group, and a camera are sequentially arranged along the optical axis; the camera is connected to a computer via a video capture card. 2) Determine the position of the graduation lines on the reticle: Before measurement, a whiteboard is placed between the optical magnifying lens group and the fixed post to remove the background image of the fixed post. The camera captures the image of the reticle and transmits it to the computer. The position of the scale line is automatically identified by the horizontal projection peak detection algorithm combined with the multi-line equidistant recognition algorithm, and the magnification ratio coefficient between the scale lines is obtained. The whiteboard is then removed. 3) Measure Young's modulus: a) Place a weight at the bottom of the test sample, and the position of the mark line on the fixed column will change accordingly; b) After the image on the surface of the fixed column is magnified by the optical magnifying lens group, the images of the scale lines of the reticle and the marking lines on the fixed column are captured by the camera and transmitted to the video capture card and then to the computer; c) The computer automatically identifies the positions of the scale lines on the reticle and the marking lines on the fixed post through a horizontal projection peak detection algorithm to achieve automatic detection of feature lines; d) Use real-time position tracking technology based on multi-frame analysis to perform dynamic stability detection and determine whether the position of the marker line is stable. If the position of the marker line is unstable, return to step b). If the position of the marker line is stable, it indicates that the stretching or compression process has ended and proceed to the next step. e) The position of the marker line is transmitted to the AI ​​guidance module. The AI ​​guidance module determines whether the elongation or shrinkage of the test sample is reasonable based on accepted values. If it is too large or too small, an operational error exists. Data with operational errors is not recorded. Based on the knowledge base content, the analysis of operational errors corresponding to excessively large or small values ​​provides corresponding modification suggestions; f) Change the mass of the weights and repeat steps a) to e) to perform multiple sets of measurements and obtain multiple sets of measurement data; g) Based on the positional change of the marking line relative to the scale line, and combined with the magnification ratio coefficient between the scale lines, the elongation or shrinkage of the test sample is calculated, so as to realize the identification of elongation and shrinkage through computer vision, and the Young's modulus of the test sample is calculated by the method of successive differences.

2. The measurement method as described in claim 1, characterized in that, The algorithm for automatically identifying the position of candidate scale lines through horizontal projection peak detection includes the following steps: i. Convert the image to grayscale, resulting in a grayscale image where each pixel has a corresponding grayscale value; ii. Overlay the grayscale values ​​of each row, where a row refers to the horizontal coordinate, to obtain the row grayscale values; iii. Based on the row grayscale values, find the peak grayscale value and use the position of the peak grayscale value as the position of the candidate tick line.

3. The measurement method as described in claim 2, characterized in that, In step 2), a multi-line equidistant recognition algorithm is used to identify multiple lines with equal spacing between two adjacent candidate scale lines as scale lines; and the ratio coefficient between the distance between scale lines on the image and the actual distance between scale lines is automatically calibrated to obtain the magnification ratio coefficient between scale lines.

4. The measurement method as described in claim 1, characterized in that, The position of the marker line is automatically identified using a horizontal projection peak detection algorithm, including the following steps: i. Convert the image to grayscale, resulting in a grayscale image where each pixel has a corresponding grayscale value; ii. Overlay the grayscale values ​​of each row, where a row refers to the horizontal coordinate, to obtain the row grayscale values; iii. Based on the row grayscale values, find the peak grayscale value and locate the position of the marker line with the maximum grayscale value peak.

5. The measurement method as described in claim 1, characterized in that, In step 3) d), dynamic stability detection is performed using real-time position tracking technology based on multi-frame analysis: images of the marker line are acquired frame by frame, and the position of the marker line is compared frame by frame. If the position change of the marker line is less than the threshold for multiple consecutive frames, it indicates that the elongation or contraction has stabilized.

6. A Young's modulus measurement system for experimental teaching, characterized in that, The measurement system includes: an optical magnifying lens assembly, a camera, a video capture card, and a computer. A reticle, made of a light-transmitting material, is positioned vertically within the optical magnifying lens assembly and has multiple horizontally spaced graduation lines. A fixed post, the optical magnifying lens assembly, and the camera are sequentially arranged along the optical axis. The camera is connected to the computer via the video capture card. Before measurement, the graduation lines on the reticle are calibrated. A white board is placed between the optical magnifying lens assembly and the fixed post to remove the background image of the fixed post, ensuring the camera only captures the image of the reticle. The image of the reticle captured by the camera is transmitted to the computer, where a horizontal projection peak detection algorithm combined with a multi-line equidistant recognition algorithm automatically identifies the position of the graduation lines and obtains the magnification between them. The scaling factor is used to measure the shrinkage or elongation of the test sample. The whiteboard is removed, and a weight is placed at the bottom of the test sample. The sample is stretched by the weight, causing the position of the marking line on the fixed column to change. The image of the fixed column surface is magnified by an optical magnifying lens group. The images of the reticle's scale lines and the marking lines on the fixed column are captured by a camera and transmitted to a video capture card, then to a computer. The computer automatically identifies the positions of the reticle's scale lines and the marking lines on the fixed column using a horizontal projection peak detection algorithm. Multiple measurements are performed by changing the mass of the weight. Based on the change in the position of the marking line relative to the scale line and combined with the magnification scaling factor between the scale lines, the shrinkage or elongation of the test sample is calculated. This allows for the identification of shrinkage and elongation through computer vision, and the Young's modulus of the test sample is calculated using the successive difference method.

7. The measurement system as described in claim 6, characterized in that, The reticle is made of a light-transmitting material.

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