A thickness measurement method for flexible materials

Abstract

The invention relates to the technical field of material thickness measurement, and specifically discloses a thickness measurement method for flexible materials. The method comprises the following steps: laying a flexible material to be tested on a test workbench, setting a cooling time, observing the temperature of the flexible material to be tested corresponding to each cooling time point, determining that when the flexible material to be tested is in a standard test state, gradually applying prestress to the flexible material to be tested until wrinkles are generated in the flexible material to be tested; analyzing the wrinkle image of the flexible material to be tested by using image processing software, and extracting the wavelength of the wrinkles corresponding to the flexible material to be tested; thereby measuring the thickness of the flexible material to be tested, the wrinkle behavior under cooling and prestress, and using image processing technology to analyze the wrinkle wavelength to infer the thickness, which can avoid direct contact and reduce the influence on the material, thereby improving the accuracy and reliability of the measurement, and also providing important data support for the subsequent use of the flexible material.

Description

Technical Field

[0001] The invention belongs to the technical field of material thickness measurement and relates to a thickness measurement method for flexible materials. Background Art

[0002] Flexible materials are increasingly used in modern industry and manufacturing. From flexible circuit boards in electronic devices to flexible sensors in the medical field to packaging materials in daily life, flexible materials have become a key component in many industries due to their unique physical properties and versatility. However, as these materials become more popular in various applications, how to accurately measure and control their thickness has become a critical issue. The thickness of flexible materials not only directly affects the performance and quality of the product, but also the efficiency and cost of the production process.

[0003] Current technology has some significant drawbacks in flexible material thickness measurement:

[0004] (1) Traditional thickness measurement methods, such as mechanical contact measurement and laser measurement, often fail to provide sufficient accuracy. Mechanical contact measurement can easily cause indentations or deformations on the surface of flexible materials, thus affecting the accuracy of the measurement results; while laser measurement may be affected by the reflectivity and light transmittance of the material surface, resulting in data errors.

[0005] (2) The physical properties of flexible materials, such as elasticity, flexibility, and deformation ability, make it difficult for measurement equipment to maintain a stable measurement environment in practical applications. These materials may undergo slight deformations under the influence of force, temperature changes, or other external conditions, further increasing the complexity and uncertainty of the measurement. In addition, flexible materials usually have irregular surface structures, and traditional measurement methods have difficulty obtaining consistent measurement results on uneven surfaces. Summary of the invention

[0006] In view of the above problems in the prior art, the present invention provides a thickness measurement method for flexible materials to solve the above technical problems.

[0007] In order to achieve the above purpose and other purposes, the technical solution adopted by the present invention is as follows:

[0008] In one aspect, the present invention provides a method for measuring the thickness of a flexible material, the method comprising the following steps:

[0009] Step S1, laying the flexible material to be tested on a test workbench, setting the cooling time, observing the temperature of the flexible material to be tested corresponding to each cooling time point, and determining that when the flexible material to be tested is in a standard test state, proceeding to step S2;

[0010] Step S2, gradually applying prestress to the flexible material to be tested until wrinkles are generated in the flexible material to be tested, and simultaneously recording the critical prestress when wrinkles are generated in the flexible material to be tested;

[0011] Step S3, using image processing software to analyze the wrinkle image of the flexible material to be tested, and extracting the wavelength of the wrinkles corresponding to the flexible material to be tested;

[0012] Step S4: Based on the wavelength of the wrinkles of the flexible material to be measured, the physical parameters of the flexible material to be measured are obtained to measure the thickness of the flexible material to be measured.

[0013] In the above method, the logic for determining whether the flexible material to be tested is in the standard test state is:

[0014] Set the cooldown interval based on the cooldown duration , then the temperature change rate of the flexible material to be tested at each cooling time point within the cooling time is expressed as , i is the number of each cooling time point, i=1,2,... , is the temperature of the flexible material corresponding to the i-th cooling time point, d is the differential sign;

[0015] Calculate the average temperature change rate of the flexible material under test during the cooling time , is the total number of cooling time points;

[0016] Calculate the standard deviation of the temperature change rate of the flexible material under test during the cooling time ;

[0017] but , is the set judgment threshold.

[0018] In the above method, the logic for determining whether the flexible material to be tested has wrinkles is:

[0019] Use a high-resolution camera to collect images of the flexible material to be tested at each test time point in real time;

[0020] Using an edge detection algorithm to identify the edges of the flexible material to be tested in the image at each test time point;

[0021] The contour detection algorithm is used to identify the contour of the flexible material to be tested in the image at each test time point, thereby obtaining the contour points in the image corresponding to the flexible material to be tested at each test time point, and the sequence of each contour point is set as , ... ... ; n is the number of each contour point, n=1,2,...N, m is the number of each test time point, m=1,2,...M;

[0022] Thus, the curvature of each contour point in the image corresponding to each test time point of the flexible material to be tested is calculated. , is the first-order derivative of the nth contour point in the image corresponding to the mth test time point of the flexible material to be tested, is the second-order derivative of the nth contour point in the image corresponding to the mth test time point of the flexible material to be tested;

[0023] in, ; ;

[0024] Based on the curvature of each contour point in the corresponding image of the flexible material to be tested at each test time point, the maximum curvature value of the flexible material to be tested at each test time point is screened out. If there is a maximum curvature value at a certain test time point that is greater than the set curvature threshold and the maximum curvature values ​​of each test time point after the test time point are greater than the set curvature threshold, it is determined that the flexible material to be tested has wrinkles.

[0025] In the above method, the wavelength of the wrinkles corresponding to the flexible material to be tested is extracted, and the specific extraction process includes the following steps:

[0026] Using edge detection algorithm to identify wrinkle edges in wrinkle images corresponding to each test time point of the flexible material to be tested; extracting wrinkle lines from edge detection results;

[0027] Along the wrinkle lines in the wrinkle image corresponding to the flexible material to be tested at each test time point, determine the position coordinates of each peak in the wrinkle image corresponding to the flexible material to be tested at each test time point, wherein the peak is the highest point of the wrinkle line;

[0028] The position coordinates of each peak in the wrinkle image of the flexible material to be tested at each test time point are marked as , j is the number of each peak, j=1,2,...J, calculate the wavelength of the corresponding wrinkles of the flexible material to be tested , J is the total number of peaks, M is the total number of test time points, is the position coordinate of the j+1th peak in the wrinkle image of the flexible material to be tested at the mth test time point.

[0029] In the above method, the physical parameters of the flexible material to be measured include elastic modulus and Poisson's ratio.

[0030] In the above method, the specific logic of obtaining the elastic modulus of the flexible material to be tested is as follows:

[0031] During the test process of gradually applying prestress to the flexible material to be tested, the value of the prestress applied in each test is recorded in real time. And the elongation of the flexible material under test in each test ;

[0032] And obtain the initial length L and cross-sectional area A of the flexible material to be tested;

[0033] Calculate the elastic modulus of the flexible material to be tested , c is the number of each test applied, c=1,2,...q, q is the total number of tests applied.

[0034] In the above method, the specific logic of obtaining the Poisson's ratio of the flexible material to be tested is as follows:

[0035] During the test process of gradually applying prestress in the longitudinal direction of the flexible material to be tested, the longitudinal deformation of the flexible material to be tested under each test is recorded in real time. ;

[0036] During the test process of gradually applying prestress in the lateral direction of the flexible material to be tested, the lateral deformation of the flexible material to be tested under each application test is recorded in real time. ;

[0037] Calculate the Poisson's ratio of the flexible material to be tested , L' represents the initial width of the flexible material to be tested.

[0038] In the above method, the thickness of the flexible material to be measured is measured, and the specific measurement process is:

[0039] Obtain the critical prestress when the flexible material to be tested produces wrinkles , calculate the thickness h of the flexible material to be tested as .

[0040] As described above, the present invention provides a method for measuring the thickness of a flexible material, which has at least the following beneficial effects:

[0041] (1) The present invention provides a method for measuring the thickness of a flexible material. The method comprises the following steps: laying the flexible material to be tested flat on a test workbench, setting a cooling time, observing the temperature of the flexible material to be tested corresponding to each cooling time point, and determining when the flexible material to be tested is in a standard test state. Prestress is then gradually applied to the flexible material to be tested until wrinkles are generated in the flexible material to be tested. The wrinkle image of the flexible material to be tested is analyzed using image processing software to extract the wavelength of the wrinkles corresponding to the flexible material to be tested. The method thus measures the thickness of the flexible material to be tested. The method has the advantages and necessity of non-contact measurement, providing comprehensive performance information, strong flexibility and adaptability, and low implementation cost, and also provides important data support for the subsequent use of the flexible material.

[0042] (2) The embodiment of the present invention realizes non-contact measurement of the thickness of flexible materials. By observing the wrinkle behavior of the material under cooling and prestressing, and using image processing technology to analyze the wrinkle wavelength to infer the thickness, direct contact can be avoided, reducing the impact on the material, thereby improving the accuracy and reliability of the measurement.

[0043] (3) The embodiments of the present invention can obtain the performance of the material under different conditions by observing the temperature change of the material during the cooling process and the wrinkle behavior under the action of prestress. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for describing the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0045] Figure 1 It is a schematic diagram of the connection of each step of the method of the present invention. DETAILED DESCRIPTION

[0046] The above contents in combination with the implementation of the present invention are merely examples and explanations of the concept of the present invention. The technical personnel in the relevant technical field may make various modifications or supplements to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the concept of the invention or exceed the scope defined by the claims, they shall all fall within the protection scope of the present invention.

[0047] Example 1

[0048] See also Figure 1 As shown, a method for measuring the thickness of a flexible material comprises the following steps:

[0049] Step S1, laying the flexible material to be tested on a test workbench, setting the cooling time, observing the temperature of the flexible material to be tested corresponding to each cooling time point, and determining that when the flexible material to be tested is in a standard test state, proceeding to step S2;

[0050] Based on the above embodiment, the logic for determining whether the flexible material to be tested is in the standard test state is:

[0051] Set the cooldown interval based on the cooldown duration , then the temperature change rate of the flexible material to be tested at each cooling time point within the cooling time is expressed as , i is the number of each cooling time point, i=1,2,... , is the temperature of the flexible material corresponding to the i-th cooling time point, d is the differential sign;

[0052] Calculate the average temperature change rate of the flexible material under test during the cooling time , is the total number of cooling time points;

[0053] Calculate the standard deviation of the temperature change rate of the flexible material under test during the cooling time ;

[0054] but , is the set judgment threshold.

[0055] The embodiment of the present invention realizes non-contact measurement of the thickness of flexible materials. By observing the wrinkle behavior of the material under cooling and prestressing, and using image processing technology to analyze the wrinkle wavelength to infer the thickness, direct contact can be avoided, the impact on the material can be reduced, and the accuracy and reliability of the measurement can be improved.

[0056] Step S2, gradually applying prestress to the flexible material to be tested until wrinkles are generated in the flexible material to be tested, and simultaneously recording the critical prestress when wrinkles are generated in the flexible material to be tested;

[0057] On the basis of the above embodiment, a high-resolution camera is used to collect images of the flexible material to be tested at each test time point in real time;

[0058] Use the Canny edge detection algorithm to identify the edges of the flexible material to be tested in the image at each test time point;

[0059] import cv2

[0060] import numpy as np

[0061] # Read the image

[0062] image = cv2.imread('material_image.jpg', cv2.IMREAD_GRAYSCALE)

[0063] # Gaussian filter denoising

[0064] blurred = cv2.GaussianBlur(image, (5, 5), 0)

[0065] # Canny edge detection

[0066] edges = cv2.Canny(blurred, 50, 150)

[0067] The contour detection algorithm is used to identify the contour of the flexible material to be tested in the image at each test time point, thereby obtaining the contour points in the image corresponding to the flexible material to be tested at each test time point, and the sequence of each contour point is set as , ... ... ; n is the number of each contour point, n=1,2,...N, m is the number of each test time point, m=1,2,...M;

[0068] Thus, the curvature of each contour point in the image corresponding to each test time point of the flexible material to be tested is calculated. , is the first-order derivative of the nth contour point in the image corresponding to the mth test time point of the flexible material to be tested, is the second-order derivative of the nth contour point in the image corresponding to the mth test time point of the flexible material to be tested;

[0069] in, ; ;

[0070] Based on the curvature of each contour point in the corresponding image of the flexible material to be tested at each test time point, the maximum curvature value of the flexible material to be tested at each test time point is screened out. If there is a maximum curvature value at a certain test time point that is greater than the set curvature threshold and the maximum curvature values ​​of each test time point after the test time point are greater than the set curvature threshold, it is determined that the flexible material to be tested has wrinkles.

[0071] Step S3, using image processing software to analyze the wrinkle image of the flexible material to be tested, and extracting the wavelength of the wrinkles corresponding to the flexible material to be tested;

[0072] On the basis of the above embodiment, the wavelength of the wrinkles corresponding to the flexible material to be tested is extracted, and the specific extraction process includes the following steps:

[0073] Use edge detection algorithm to identify the wrinkle edges in the wrinkle images corresponding to the flexible material to be tested at each test time point; extract wrinkle lines from the edge detection results, and use Hough transform to detect wrinkle lines;

[0074] Along the wrinkle lines in the wrinkle image corresponding to the flexible material to be tested at each test time point, determine the position coordinates of each peak in the wrinkle image corresponding to the flexible material to be tested at each test time point, wherein the peak is the highest point of the wrinkle line;

[0075] The position coordinates of each peak in the wrinkle image of the flexible material to be tested at each test time point are marked as , j is the number of each peak, j=1,2,...J, calculate the wavelength of the corresponding wrinkles of the flexible material to be tested , J is the total number of peaks, M is the total number of test time points, is the position coordinate of the j+1th peak in the wrinkle image of the flexible material to be tested at the mth test time point.

[0076] Step S4: Based on the wavelength of the wrinkles of the flexible material to be measured, the physical parameters of the flexible material to be measured are obtained to measure the thickness of the flexible material to be measured.

[0077] Based on the above embodiment, the physical parameters of the flexible material to be measured include elastic modulus and Poisson's ratio.

[0078] Based on the above embodiment, the specific logic of obtaining the elastic modulus of the flexible material to be tested is as follows:

[0079] During the test process of gradually applying prestress to the flexible material to be tested, the value of the prestress applied in each test is recorded in real time. And the elongation of the flexible material under test in each test ;

[0080] And obtain the initial length L and cross-sectional area A of the flexible material to be tested;

[0081] Calculate the elastic modulus of the flexible material to be tested , c is the number of each test applied, c=1,2,...q, q is the total number of tests applied.

[0082] Based on the above embodiment, the specific logic of obtaining the Poisson's ratio of the flexible material to be tested is as follows:

[0083] During the test process of gradually applying prestress in the longitudinal direction of the flexible material to be tested, the longitudinal deformation of the flexible material to be tested under each test is recorded in real time. ;

[0084] During the test process of gradually applying prestress in the lateral direction of the flexible material to be tested, the lateral deformation of the flexible material to be tested under each application test is recorded in real time. ;

[0085] Calculate the Poisson's ratio of the flexible material to be tested , L' represents the initial width of the flexible material to be tested.

[0086] On the basis of the above embodiment, the thickness of the flexible material to be measured is measured, and the specific measurement process is as follows:

[0087] Obtain the critical prestress when the flexible material to be tested produces wrinkles , calculate the thickness h of the flexible material to be tested as .

[0088] The present invention provides a thickness measurement method for flexible materials. The method comprises the following steps: laying the flexible material to be tested flat on a test workbench, setting a cooling time, observing the temperature of the flexible material to be tested corresponding to each cooling time point, and determining that when the flexible material to be tested is in a standard test state, gradually applying prestress to the flexible material to be tested until wrinkles are generated in the flexible material to be tested; using image processing software to analyze the wrinkle image of the flexible material to be tested, and extracting the wavelength of the wrinkles corresponding to the flexible material to be tested; thereby measuring the thickness of the flexible material to be tested; and having the advantages and necessity of non-contact measurement, providing comprehensive performance information, strong flexibility and adaptability, and low implementation cost. This method not only improves the accuracy and reliability of measurement, but also provides important technical support for the research and application of flexible materials, and has broad application prospects and practical value.

[0089] It should be understood that in the various embodiments of the present application, the size of the serial numbers of the above-mentioned processes does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0090] It should be understood that determining B based on A does not mean determining B only based on A. B can also be determined based on A and / or other information.

[0091] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

[0092] Finally: The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for measuring the thickness of a flexible material, characterized in that: include: Step S1, laying the flexible material to be tested on a test workbench, setting the cooling time, observing the temperature of the flexible material to be tested corresponding to each cooling time point, and determining that when the flexible material to be tested is in a standard test state, proceeding to step S2; Step S2, gradually applying prestress to the flexible material to be tested until wrinkles are generated in the flexible material to be tested, and simultaneously recording the critical prestress when wrinkles are generated in the flexible material to be tested; Step S3, using image processing software to analyze the wrinkle image of the flexible material to be tested, and extracting the wavelength of the wrinkles corresponding to the flexible material to be tested; Step S4: Based on the wavelength of the wrinkles of the flexible material to be measured, the physical parameters of the flexible material to be measured are obtained to measure the thickness of the flexible material to be measured.

2. A method for measuring thickness of flexible materials according to claim 1, characterized in that: The logic for determining that the flexible material to be tested is in the standard test state is: Set the cooldown interval based on the cooldown duration , then the temperature change rate of the flexible material to be tested at each cooling time point within the cooling time is expressed as , i is the number of each cooling time point, i=1,2,... , is the temperature of the flexible material corresponding to the i-th cooling time point, d is the differential sign; Calculate the average temperature change rate of the flexible material under test during the cooling time , is the total number of cooling time points; Calculate the standard deviation of the temperature change rate of the flexible material under test during the cooling time ; but , is the set judgment threshold.

3. A method for measuring thickness of flexible materials according to claim 1, characterized in that: The logic for determining whether the flexible material to be tested has wrinkles is: Use a high-resolution camera to collect images of the flexible material to be tested at each test time point in real time; Using an edge detection algorithm to identify the edges of the flexible material to be tested in the image at each test time point; The contour detection algorithm is used to identify the contour of the flexible material to be tested in the image at each test time point, thereby obtaining the contour points in the image corresponding to the flexible material to be tested at each test time point, and the sequence of each contour point is set as , ... ... ; n is the number of each contour point, n=1,2,...N, m is the number of each test time point, m=1,2,...M; The curvature of each contour point in the image corresponding to each test time point of the flexible material to be tested is calculated in this way. , is the first-order derivative of the nth contour point in the image corresponding to the mth test time point of the flexible material to be tested, is the second-order derivative of the nth contour point in the image corresponding to the mth test time point of the flexible material to be tested; in, ; ; Based on the curvature of each contour point in the corresponding image of the flexible material to be tested at each test time point, the maximum curvature value of the flexible material to be tested at each test time point is screened out. If there is a maximum curvature value at a certain test time point that is greater than the set curvature threshold and the maximum curvature values ​​of each test time point after the test time point are greater than the set curvature threshold, it is determined that the flexible material to be tested has wrinkles.

4. A method for measuring thickness of flexible materials according to claim 1, characterized in that: Extract the wavelength of the corresponding wrinkles of the flexible material to be tested. The specific extraction process includes the following steps: Using edge detection algorithm to identify wrinkle edges in wrinkle images corresponding to each test time point of the flexible material to be tested; extracting wrinkle lines from edge detection results; Along the wrinkle lines in the wrinkle image corresponding to the flexible material to be tested at each test time point, determine the position coordinates of each peak in the wrinkle image corresponding to the flexible material to be tested at each test time point, wherein the peak is the highest point of the wrinkle line; The position coordinates of each peak in the wrinkle image of the flexible material to be tested at each test time point are marked as , j is the number of each peak, j=1,2,...J, calculate the wavelength of the corresponding wrinkles of the flexible material to be tested , J is the total number of peaks, M is the total number of test time points, is the position coordinate of the j+1th peak in the wrinkle image of the flexible material to be tested at the mth test time point.

5. A method for measuring thickness of flexible materials according to claim 1, characterized in that: The physical parameters of the flexible material to be tested include elastic modulus and Poisson's ratio.

6. A method for measuring thickness of flexible materials according to claim 5, characterized in that: The specific logic for obtaining the elastic modulus of the flexible material to be tested is as follows: During the test process of gradually applying prestress to the flexible material to be tested, the value of the prestress applied in each test is recorded in real time. And the elongation of the flexible material under test in each test ; And obtain the initial length L and cross-sectional area A of the flexible material to be tested; Calculate the elastic modulus of the flexible material to be tested , c is the number of each test applied, c=1,2,...q, q is the total number of tests applied.

7. A method for measuring thickness of flexible materials according to claim 5, characterized in that: The specific logic for obtaining the Poisson's ratio of the flexible material to be tested is as follows: During the test process of gradually applying prestress in the longitudinal direction of the flexible material to be tested, the longitudinal deformation of the flexible material to be tested under each test is recorded in real time. ; During the test process of gradually applying prestress in the lateral direction of the flexible material to be tested, the lateral deformation of the flexible material to be tested under each application test is recorded in real time. ; Calculate the Poisson's ratio of the flexible material to be tested , L' represents the initial width of the flexible material to be tested.

8. A method for measuring thickness of flexible materials according to claim 1, characterized in that: Calculate the thickness of the flexible material to be measured. The specific measurement process is as follows: Obtain the critical prestress when the flexible material to be tested produces wrinkles , calculate the thickness h of the flexible material to be tested as .

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