Method and system for evaluating residual life of polyester film

Abstract

The invention discloses a polyester film residual life evaluation method and system. The method comprises the following steps: acquiring first data and second data of a sample polyester film, and establishing a first life acquisition model according to the first data; preprocessing the second data, and establishing a second tensile strength quantitative evaluation model according to the preprocessed second data; and determining the residual life of the to-be-tested polyester film according to the first life acquisition model and the second tensile strength quantitative evaluation model. Complex operation is avoided, operation requirements of testing are reduced, and the problem that the aging state of the polyester film is difficult to evaluate on site is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of polyester film evaluation, and in particular to a method and system for evaluating the remaining life of a polyester film. Background Art

[0002] Polyester films (such as PET films) are widely used in electrical equipment such as transformers, generators, and motors due to their excellent electrical insulation properties, mechanical strength, and thermal stability, especially as winding insulation materials or slot insulation materials. Compared with other high-performance films (such as polyimide films), polyester films are relatively low in cost, but still provide good electrical and mechanical properties, and are suitable for the insulation needs of medium and low voltage power equipment. When power equipment is energized for a long time, the polyester film gradually ages under the dominance of thermal stress, and its insulation properties and mechanical strength will decrease. When the polyester film ages severely, the power equipment must be withdrawn from operation. Therefore, effectively judging the degree of aging of polyester film is of great significance for evaluating the operating life of power equipment.

[0003] For newly commissioned polyester film materials, thermal aging is used to evaluate their long-term heat resistance, and the retention rate of the initial value of tensile strength under a specific temperature index (TI) is used to test their performance. For example, when TI ≥ 115, the tensile strength retains 50% of the initial value. For polyester film materials that have already been put into operation, testing their tensile strength retention rate (current tensile strength / initial tensile strength) can better reflect their aging degree. When the tensile strength drops to 50% of the initial value, it is considered to have reached the end of its life.

[0004] At present, in practical applications, the tensile strength of polyester film needs to be tested to evaluate its service life. However, the tensile strength test method for polyester films with different aging degrees requires sampling of the polyester film of the power equipment and making tensile samples of standard shapes. The entire testing process has problems such as damaging the insulation structure of the power equipment, taking a long time to test, and requiring high levels of testers. It is difficult to use it for on-site equipment aging status assessment. Summary of the invention

[0005] The purpose of this section is to summarize some aspects of embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the specification abstract and the invention title of this application to avoid blurring the purpose of this section, the specification abstract and the invention title, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0006] In view of the above existing problems, the present invention is proposed.

[0007] Therefore, the present invention provides a method and system for evaluating the remaining life of a polyester film, which can solve the problems mentioned in the background technology.

[0008] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0009] In a first aspect, the present invention provides a method for evaluating the remaining life of a polyester film, comprising:

[0010] Acquire first data and second data of a sample polyester film, and establish a first life acquisition model according to the first data;

[0011] Preprocessing the second data, and establishing a second tensile strength quantitative evaluation model according to the preprocessed second data;

[0012] The remaining life of the polyester film to be tested is determined according to the first life acquisition model and the second tensile strength quantitative evaluation model.

[0013] As a preferred solution of the polyester film remaining life assessment method of the present invention, the preprocessing of the second data includes:

[0014] Obtain the absorbance of different layers of sample polyester film;

[0015] Determine the correlation between the absorbance of the sample polyester film and the number of layers;

[0016] The sample polyester film is a multi-layer polyester film with a preset thickness.

[0017] As a preferred embodiment of the method for evaluating the remaining life of a polyester film according to the present invention, the method of establishing a first life acquisition model according to the first data comprises:

[0018] Determine the variation law of the test life of the sample polyester film with temperature according to the first data;

[0019] A first life acquisition model is established based on the variation rule to determine the sample polyester film at a preset temperature.

[0020] As a preferred embodiment of the method for evaluating the remaining life of a polyester film of the present invention, the step of obtaining the absorbance of different layers of the sample polyester film comprises:

[0021] Determine the wavelength of the near-infrared spectrum according to the characteristic absorption peak of the sample polyester film, and set the backing material according to the application environment of the sample polyester film to construct a near-infrared spectrum collection environment;

[0022] Based on the near-infrared spectrum collection environment, a diffuse reflection collection method is used to collect the absorbance of different layers of the sample polyester film.

[0023] As a preferred embodiment of the method for evaluating the remaining life of a polyester film according to the present invention, the method for determining the remaining life of the polyester film to be tested according to the first life acquisition model and the second tensile strength quantitative evaluation model comprises:

[0024] The tensile strength of the polyester film to be tested and the tensile strength of the unaged sample polyester film are obtained by using a second tensile strength quantitative evaluation model;

[0025] The tensile strength loss rate of the polyester film to be tested is obtained by comparing the tensile strength of the polyester film to be tested with the tensile strength of the unaged sample polyester film;

[0026] The remaining life of the polyester film to be tested is obtained by the tensile strength loss rate of the polyester film to be tested and the service life of the polyester film to be tested obtained by the first life acquisition model.

[0027] As a preferred embodiment of the method for evaluating the remaining life of a polyester film according to the present invention, the preprocessing of the second data further comprises:

[0028] Determine the spectral data of the single-layer sample polyester film at different aging degrees according to the correlation;

[0029] A linear regression analysis is performed on the spectral data and the tensile strength of the samples at the corresponding aging degrees to obtain a quantitative evaluation model for the second tensile strength of the sample polyester film.

[0030] As a preferred embodiment of the method for evaluating the remaining life of a polyester film according to the present invention, the preprocessing of the second data further comprises:

[0031] Performing dimension reduction processing on the spectral data by principal component analysis to obtain spectral data after dimension reduction;

[0032] A linear regression model was established, in which the input was the spectral data after dimension reduction, and the output was the tensile strength of the sample at the corresponding aging degree. The least squares method was used to solve it and the second tensile strength quantitative evaluation model was obtained.

[0033] In a second aspect, the present invention provides a polyester film remaining life assessment system, comprising:

[0034] An acquisition module, used for acquiring first data and second data of the sample polyester film, and establishing a first life acquisition model according to the first data;

[0035] A construction module, used for preprocessing the second data and establishing a second tensile strength quantitative evaluation model according to the preprocessed second data;

[0036] A determination module is used to determine the remaining life of the polyester film to be tested according to the first life acquisition model and the second tensile strength quantitative evaluation model.

[0037] In a third aspect, the present invention provides a computer device, comprising a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps of the above-mentioned method when executing the computer program.

[0038] In a fourth aspect, the present invention provides a computer-readable storage medium having a computer program stored thereon, wherein the computer program implements the steps of the method described above when executed by a processor.

[0039] Compared with the prior art, the present invention has the following beneficial effects: the present invention proposes a method and system for evaluating the remaining life of a polyester film, obtains the first data and the second data of a sample polyester film, and establishes a first life acquisition model according to the first data; pre-processes the second data, and establishes a second tensile strength quantitative evaluation model according to the pre-processed second data; and determines the remaining life of the polyester film to be tested according to the first life acquisition model and the second tensile strength quantitative evaluation model. It avoids complex operations, reduces the operating requirements of the test, and thus solves the problem of difficulty in evaluating the aging state of the polyester film on site. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. Among them:

[0041] Figure 1 A method and system flow chart of a polyester film remaining life assessment method provided by one embodiment of the present invention;

[0042] Figure 2 A detailed operation flow chart of a polyester film remaining life assessment method and system provided by one embodiment of the present invention;

[0043] Figure 3 A schematic diagram of the system structure of a polyester film remaining life assessment method and system provided by an embodiment of the present invention;

[0044] Figure 4 An internal structural diagram of a computer device of a polyester film remaining life assessment method and system provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0045] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in the art without creative work should fall within the scope of protection of the present invention.

[0046] Example 1

[0047] Reference Figure 1-Figure 4 , which is the first embodiment of the present invention, provides a method and system for evaluating the remaining life of a polyester film, comprising:

[0048] In the existing related technologies, there are deficiencies in the evaluation of the aging status of polyester films, which are mainly reflected in the complex evaluation process, high operation requirements, and difficulty in achieving rapid on-site evaluation.

[0049] The present application provides a method that can effectively solve the above-mentioned problems. Next, multiple embodiments will be combined to explain in detail how to implement the polyester film remaining life assessment method;

[0050] Figure 1 A method and a flow chart of a system method for assessing the remaining life of a polyester film are shown, including:

[0051] S101, obtaining first data and second data of a sample polyester film, and establishing a first life acquisition model according to the first data;

[0052] In the embodiment of the present application, the first data is the change of the elongation at break of the sample polyester film at different temperatures over time, which can be used to determine the change law of the test life of the sample polyester film with temperature, and the second data is the tensile strength of the sample under different aging degrees.

[0053] In an optional embodiment, the specific content of the first data and the second data can be changed, as long as the established model is guaranteed to obtain the remaining life or any data related to the remaining life, such as the remaining life probability, the actual service life, the predicted value of the remaining life, etc., which should be within the scope of protection of this application.

[0054] In the embodiment of the present application, the elongation at break of the sample polyester film at different temperatures and the tensile strength of the sample at different aging degrees are obtained. The sample polyester film is a multi-layer polyester film with a preset thickness.

[0055] For example, first, polyester film samples can be prepared. Film samples often have different thicknesses and are used in multiple layers. Therefore, samples with a single layer thickness of ≤15 μm and a single layer thickness of >15 μm are prepared to ensure the typicality of the single layer thickness. The polyester film is cut into individual samples of 100 mm × 100 mm × 20 layers, and a total of more than 36 samples are required to ensure the typicality of the sample library.

[0056] Secondly, the aging temperature can be set to 140℃, 160℃ and 180℃ respectively, and 12 samples are placed at each temperature. For 140℃, the aging is 36 days, and the samples are taken every 3 days; for 160℃, the aging is 24 days, and the samples are taken every 2 days; for 180℃, the aging is 12 days, and the samples are taken every 1 day. In this way, a total of 36 samples with different aging degrees at different aging temperatures are obtained. In this way, it is guaranteed that the samples with tensile strength loss rate that meets the end-of-life judgment standard are obtained.

[0057] Finally, for each aged sample, 5 layers of each sample were tested, and the tensile strength calibration value of each sample was the average of 5 tests, and the tensile strength label Tsi of different aged samples was obtained. Select the aged sample whose elongation at break drops to 50% of the original at each temperature T, and record its aging time as t, and you can get t1 corresponding to T1=140℃, t2 corresponding to T2=160℃, and t3 corresponding to T3=180℃.

[0058] It should be noted that obtaining the first data and the second data of the sample polyester film can provide basic data for establishing an accurate life prediction model. By analyzing these data, a mathematical model reflecting the aging characteristics of the polyester film can be constructed, and then the remaining life of the film under different use conditions can be predicted. In addition, by comparing the tensile strength under different aging degrees, the performance degradation of the film can be more intuitively evaluated, providing a scientific basis for the maintenance and replacement of the film.

[0059] In the embodiment of the present application, establishing a first life acquisition model according to the first data includes:

[0060] Determine the variation law of the test life of the sample polyester film with temperature according to the first data;

[0061] According to the changing law, the first life acquisition model of the sample polyester film at the preset temperature is established.

[0062] In an optional embodiment, the Arrhenius equation can be used to calculate the specific expression of the law of change of the test life of the sample polyester film with temperature, and the first life acquisition model can be inferred based on the specific expression; other mathematical models can also be used to describe the relationship between the test life and temperature. For example, polynomial regression analysis, exponential decay model or other applicable statistical methods can be used to establish the model. After determining the law of change of the test life with temperature, the model can be further calibrated through experimental data to ensure the accuracy and reliability of the model. However, no matter what technology is selected to establish the first life acquisition model, as long as the input of the model is the first data (in this application, the change of the elongation at break of the sample polyester film at different temperatures over time), and the output is the service life, then the model should be within the scope of protection of this application.

[0063] In the embodiment of the present application, the Arrhenius equation is used to calculate the specific expression of the variation law of the test life of the sample polyester film with temperature, and a first life acquisition model is established. The specific steps may be:

[0064] According to the Arrhenius equation

[0065]

[0066] Where k is the reaction rate constant (for material aging, it is usually proportional to the inverse of the life span, i.e. k = 1 / t); A is the pre-exponential factor, E a is the activation energy, R is the gas constant, T is the absolute temperature, and the equation is linearized to obtain:

[0067]

[0068] By substituting T1 and t1, T2 and t2, T3 and t3, the slope Ea / R and intercept -lnA of the linear equation can be obtained. By extrapolating the equation, the first life acquisition model of the sample at the normal operating temperature of the equipment can be obtained.

[0069] It should be noted that the use of the Arrhenius equation to establish the first life acquisition model can provide a relatively simple and widely applicable mathematical framework to describe the temperature dependence of the material aging process. Through the Arrhenius equation, aging data at different temperatures can be correlated to predict the aging behavior at any temperature. In addition, the linear nature of the equation makes data processing more intuitive and easy, which is convenient for quickly evaluating the remaining life of polyester film in practical applications.

[0070] S102, preprocessing the second data, and establishing a second tensile strength quantitative evaluation model according to the preprocessed second data;

[0071] In the embodiment of the present application, preprocessing the second data includes:

[0072] Obtain the absorbance of different layers of sample polyester film;

[0073] Determine the correlation between the absorbance of the sample polyester film and the number of layers;

[0074] The sample polyester film is a multi-layer polyester film with a preset thickness.

[0075] In an optional embodiment, the absorbance of different layers of the sample polyester film can be obtained by diffuse reflection collection, or by other non-contact measurement techniques, such as infrared spectroscopy or ultraviolet-visible spectroscopy; or by other non-contact optical measurement techniques, such as Fourier transform infrared spectroscopy (FTIR) or ultraviolet-visible spectroscopy (UV-Vis). Through these techniques, the absorbance data of the sample polyester film at different aging stages can be obtained, and then the relationship between the absorbance data and the aging degree can be analyzed. After determining the correlation between the absorbance and the number of layers, a quantitative evaluation model can be established, which can infer the number of layers of the film based on the absorbance data, thereby evaluating its overall physical properties and aging status.

[0076] In the embodiment of the present application, obtaining the absorbance of different layers of the sample polyester film includes:

[0077] Determine the near-infrared spectrum wavelength according to the characteristic absorption peak of the sample polyester film, set the backing material according to the application environment of the sample polyester film, and construct the near-infrared spectrum collection environment;

[0078] Based on the near-infrared spectrum collection environment, the diffuse reflection collection method is used to collect the absorbance of different layers of sample polyester film.

[0079] Exemplarily, near-infrared spectra of all aged samples are collected. Since the characteristic absorption peak of polyester film generally appears between 1200nm and 1800nm, a 900-2200nm near-infrared spectrometer is used to collect the spectrum. The resolution of the spectrometer should be better than 7nm, and diffuse reflection collection is adopted.

[0080] In an optional embodiment, considering the transparency of the polyester film, the materials such as the windings it covers will affect the spectrum of the polyester film. Therefore, when collecting the spectrum, it is necessary to simulate the backing material of the polyester film in the power equipment. For example, for the transformer, a copper plate is placed under the polyester film to simulate the situation where the polyester film acts as winding insulation.

[0081] In an optional embodiment, the polyester film samples on different structures have different numbers of layers, resulting in differences in near-infrared spectra. When collecting near-infrared spectra, it is necessary to correct the spectral differences caused by thickness differences. The specific implementation method is to collect the near-infrared spectra of each sample at 3 layers, 6 layers, 9 layers, 12 layers and 15 layers respectively.

[0082] In an optional embodiment, the absorbance L is linearly related to the number of layers, and the absorbance can be determined according to the Beer-Lambert law:

[0083] Ab(λ,L)=L·ε(λ)·c

[0084] Among them, Ab(λ,L) is the absorbance at wavelength λ, L is the number of film layers, ε(λ) is the molar absorption coefficient at wavelength, and c is the constant of film material properties.

[0085] For each wavelength point, the relationship between absorbance and number of layers was obtained by linear regression fitting using spectral data of different numbers of layers.

[0086] Ab(λ,L)=m·L·A(λ,1)

[0087] Where m is the fitting coefficient. Through this fitting, the absorbance Ab(λ,1) of the single-layer film at each wavelength λ can be obtained.

[0088] In an optional embodiment, assuming that the spectrum Ab(λ,L) of a multilayer film has been obtained, the spectrum can be converted into the spectrum of a single-layer film by performing layer number correction according to the fitting relationship:

[0089] Ab(λ,1)=Ab(λ,L) / mL

[0090] Through the above steps, the multi-layer spectrum can be corrected to a single-layer spectrum. Finally, the spectrum data S of different aging times are obtained. i Usually, the number of features in the spectrum S is related to the number of pixels in the spectrometer detector, with typical values ​​being 256 or 512.

[0091] In an optional embodiment, the correlation between the absorbance and the number of layers of the sample polyester film can also be determined by methods other than Beer-Lambert's law, for example, by Fourier transform infrared spectroscopy (FTIR) technology. FTIR is a powerful analytical tool that can provide detailed information about the chemical structure of the material. Through FTIR analysis, infrared spectra of the sample polyester film at different aging stages can be obtained. By analyzing the changes in the absorption peak intensity of specific chemical bonds in the spectrum, the degree of aging of the film can be inferred. For example, as the aging process proceeds, certain chemical bonds may break or form, resulting in changes in the absorption peak intensity at specific wave numbers. Through these changes, a model for the correlation between absorbance and the number of layers based on FTIR data can be established to evaluate the physical properties and aging state of the polyester film.

[0092] In an optional embodiment, UV-visible spectroscopy analysis technology can also be used. UV-visible spectroscopy analysis is an analysis method based on the absorption characteristics of ultraviolet and visible light by a substance. Through UV-visible spectroscopy analysis, spectral data of the sample polyester film at different aging stages can be obtained. Since the electronic structure of the material may change during the aging process, this will affect its absorption characteristics of light. By analyzing these changes, a model of the correlation between absorbance and the number of layers based on UV-visible spectroscopy data can be established to evaluate the physical properties and aging state of the polyester film.

[0093] In the embodiment of the present application, preprocessing the second data further includes:

[0094] According to the correlation, the spectral data of the single-layer sample polyester film at different aging degrees are determined;

[0095] A linear regression analysis was performed on the spectral data and the tensile strength of the samples at the corresponding aging degree to obtain a quantitative evaluation model for the second tensile strength of the sample polyester film.

[0096] In the embodiment of the present application, preprocessing the second data further includes:

[0097] The spectral data is subjected to dimension reduction processing by principal component analysis to obtain the spectral data after dimension reduction;

[0098] A linear regression model was established, in which the input was the spectral data after dimension reduction, and the output was the tensile strength of the sample at the corresponding aging degree. The least squares method was used to solve it and the second tensile strength quantitative evaluation model was obtained.

[0099] In the embodiment of the present application, the collected spectral data sets {S1, S2, ..., S i}Perform principal component analysis to obtain the principal components with the top 95% contribution rate. Using this method, we can obtain the sample spectral data Pi after dimension reduction. Compared with S, Pi The number of features is smaller, usually no more than 10, which is more conducive to multiple linear regression modeling analysis.

[0100] Secondly, a linear regression model is established, in which the input value is {P1,P2,…,P i}, the output is the corresponding value {T s1 ,T s2 ,…,T si}, use the least squares method to bias the regression coefficients β0 to β1~β m , where m is the number of features after dimensionality reduction.

[0101]

[0102] Finally, a quantitative evaluation model of the second tensile strength of the sample was obtained.

[0103] It should be noted that establishing a linear regression model and solving it using the least squares method can effectively reduce the computational complexity and improve the operational efficiency of the model. In addition, the regression coefficient obtained by the least squares method can accurately reflect the linear relationship between the spectral data and the tensile strength of the sample, thereby providing reliable data support for the remaining life assessment of the polyester film. In practical applications, the model can quickly predict the tensile strength of the polyester film at different aging stages, providing a scientific basis for the safe operation of power equipment. In this way, the health of the polyester film can be effectively monitored and evaluated, and equipment failures caused by film aging can be prevented, thereby improving the stability and safety of the entire power system.

[0104] S103, determining the remaining life of the polyester film to be tested according to the first life acquisition model and the second tensile strength quantitative evaluation model.

[0105] In the embodiment of the present application, determining the remaining life of the polyester film to be tested according to the first life acquisition model and the second tensile strength quantitative evaluation model includes:

[0106] The tensile strength of the polyester film to be tested and the tensile strength of the unaged sample polyester film are obtained by using a second tensile strength quantitative evaluation model;

[0107] Furthermore, the tensile strength loss rate of the polyester film to be tested is obtained by comparing the tensile strength of the polyester film to be tested with the tensile strength of the unaged sample polyester film;

[0108] Furthermore, the remaining life of the polyester film to be tested is obtained by using the tensile strength loss rate of the polyester film to be tested and the service life of the polyester film to be tested obtained by the first life acquisition model.

[0109] For example, for a sample of unknown aging state, the spectrum S is acquired by using the above-mentioned spectrometer and acquisition method.x , use the principal component analysis to record the load vector to obtain the reduced-dimensional spectrum P x Then, the tensile strength Ts of the polyester film was obtained using the established quantitative evaluation model. i .

[0110] Secondly, the tensile strength T of the sample sx The tensile strength loss rate of the unaged sample is obtained by comparing it with the tensile strength of the unaged sample. The service life at the operating temperature is obtained by the above analysis. The formula L x / L0=(T s50％ -T sx ) / (T s0 -T s50％ ), and the remaining life L of the polyester film is obtained. x .

[0111] It should be noted that, by adopting the above method, firstly, the sample polyester film is subjected to aging treatment at different temperatures to obtain the service life of the polyester film at a preset temperature, so that a simulation can be performed in advance, and the ambient temperature of the target polyester film to be tested is simulated by the preset temperature to obtain the initial service life of the target polyester film, thereby avoiding a time-consuming life test; secondly, the absorbance of the single-layer polyester film is obtained by collecting near-infrared spectra of the sample polyester film after different degrees of aging treatment, and a linear regression analysis is performed on the absorbance and the degree of aging to obtain a quantitative evaluation model for the tensile strength of the polyester film. In this way, an evaluation model suitable for the target polyester film can be obtained by processing and analyzing the sample polyester film, which can avoid damage to the target polyester film. Finally, the remaining life of the target polyester film is determined in combination with the service life and the evaluation model. In this way, not only the remaining life of the target polyester film to be tested can be accurately obtained, but also complex operations can be avoided, thereby reducing the operational requirements of the test.

[0112] This embodiment also provides a polyester film remaining life assessment system, including:

[0113] An acquisition module, used for acquiring first data and second data of the sample polyester film, and establishing a first life acquisition model according to the first data;

[0114] A construction module is used to preprocess the second data and establish a second tensile strength quantitative evaluation model according to the preprocessed second data;

[0115] The determination module is used to determine the remaining life of the polyester film to be tested according to the first life acquisition model and the second tensile strength quantitative evaluation model.

[0116] The above-mentioned unit modules may be embedded in or independent of a processor in a computer device in the form of hardware, or may be stored in a memory in a computer device in the form of software, so that the processor can call and execute operations corresponding to the above-mentioned modules.

[0117] This embodiment also provides a computer device, which may be a terminal, and its internal structure diagram may be as shown in FIG. Figure 4 As shown. The computer device includes a processor, a memory, a communication interface, a display screen and an input device connected through a system bus. Among them, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The communication interface of the computer device is used to communicate with an external terminal in a wired or wireless manner, and the wireless manner can be achieved through WIFI, an operator network, NFC (near field communication) or other technologies. When the computer program is executed by the processor, a method for evaluating the remaining life of a polyester film is implemented. The display screen of the computer device can be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer device can be a touch layer covered on the display screen, or a button, trackball or touchpad set on the computer device housing, or an external keyboard, touchpad or mouse, etc.

[0118] This embodiment further provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the following steps are implemented:

[0119] Acquire first data and second data of the sample polyester film, and establish a first life acquisition model according to the first data;

[0120] Preprocessing the second data, and establishing a second tensile strength quantitative evaluation model based on the preprocessed second data;

[0121] The remaining life of the polyester film to be tested is determined according to the first life acquisition model and the second tensile strength quantitative evaluation model.

[0122] Example 2

[0123] Reference Figure 2 , is an embodiment of the present invention, and provides a specific embodiment of a polyester film remaining life assessment method, wherein 201-204 is a polyester film sample preparation and performance testing stage, 205-208 is a near infrared spectrum acquisition and modeling stage, and 209-212 is a test sample aging state assessment stage;

[0124] During the polyester film sample preparation and performance testing stage:

[0125] Among them, 201 prepares polyester film samples. Film samples often have different thicknesses and are used in multiple layers. In this embodiment, 6020-type samples with a single layer thickness of 15 μm and a single layer thickness of 75 μm are prepared to ensure the typicality of the single layer thickness. The polyester film is cut into a single sample of 100 mm × 100 mm × 20 layers, and a total of 36 samples are required to ensure the typicality of the sample library.

[0126] Furthermore, 202 carried out accelerated heat aging experiments with reference to the aging procedure of GB / T 11026 "Heat resistance of electrical insulating materials". The aging temperatures were set at 140°C, 160°C and 180°C, and 12 samples were placed at each temperature. Referring to the recommended exposure temperature and time in GB / T11026, for 140°C, aging was 36 days, and sampling was done every 3 days; for 160°C, aging was 24 days, and sampling was done every 2 days; for 180°C, aging was 12 days, and sampling was done every 1 day. In this way, a total of 36 samples with different aging degrees at different aging temperatures were obtained. In this way, it can be ensured that the samples with tensile strength loss rate that meets the end-of-life judgment standard are obtained.

[0127] Furthermore, for each aged sample, the tensile strength test was carried out with reference to GB / T 13022 "Test method for tensile properties of plastic films". Five layers of each sample were tested. The tensile strength calibration value of each sample was the average of the five tests, and the tensile strength label T of different aged samples was obtained. si The test results are shown in Table 1.

[0128] Table 1 Test results of polyester film

[0129]

[0130] Select the aged sample whose elongation at break drops to 50% of the original at each temperature T, and record its aging time as t. For this embodiment, the aging termination time corresponding to T1=140°C is 33 days, the aging termination time corresponding to T2=160°C is 14 days, and the aging termination time corresponding to T3=180°C is 6 days.

[0131] Furthermore, 204 fits the life-temperature formula through Table 2;

[0132] Table 2 Aging termination time of polyester film at various exposure temperatures

[0133] Temperature(℃) Temperature (K) <![CDATA[1 / T(K -1 )]]> Lifespan (h) lnt 140 413.15 0.002420 792 6.67 160 433.15 0.002309 336 5.82 180 463.15 0.002207 144 4.97

[0134] The Arrhenius life-temperature formula is obtained as

[0135]

[0136] When T is the normal operating temperature of 80°C, the lifespan is 32150 hours, or about 88 years. It can be seen that polyester film has a long lifespan.

[0137] Near-infrared spectra of all aged samples were collected. Since the characteristic absorption peak of polyester film generally appears between 1200nm and 1800nm, a 900-2200nm near-infrared spectrometer was used to collect the spectra. The resolution of the spectrometer should be better than 7nm, and diffuse reflection collection was adopted.

[0138] In the near infrared spectrum acquisition and modeling stage:

[0139] Among them, 205 near infrared spectra were collected for all aged samples. Since the characteristic absorption peak of polyester film generally appears between 1200nm and 1800nm, a 900-2200nm near infrared spectrometer was used to collect the spectrum. The spectrometer model of this embodiment is NIR Quest+2.2, the spectrometer resolution is 5nm, and diffuse reflection collection is adopted. The polyester film used in this embodiment is used for gas transformer winding insulation. Therefore, when collecting the spectrum, a 2mm copper plate is placed under the polyester film to simulate the situation where the polyester film acts as winding insulation.

[0140] Furthermore, the number of layers of polyester film samples on different structures 206 is different, resulting in differences in near-infrared spectra. When collecting near-infrared spectra, it is necessary to correct the spectral differences caused by thickness differences. The specific implementation method is to collect the near-infrared spectra of each sample at 3 layers, 6 layers, 9 layers, 12 layers and 15 layers respectively. The near-infrared spectra have absorbance as the ordinate and wavelength as the abscissa.

[0141] Generally, the absorbance L is linearly related to the number of layers, according to Beer-Lambert's law

[0142] Ab(λ,L)=L·ε(λ)·c

[0143] Among them, Ab(λ,L) is the absorbance at wavelength λ, L is the number of film layers, ∈(λ) is the molar absorption coefficient at wavelength λ, and c is the constant of the film material property. For each wavelength point, the relationship between absorbance and number of layers is obtained by linear regression fitting using spectral data of different numbers of layers.

[0144] Ab(λ,L)=m·L·A(λ,1)

[0145] Where m is the fitting coefficient. Through this fitting, the absorbance Ab(λ,1) of a single-layer film at each wavelength λ can be obtained. Assuming that the spectrum Ab(λ,L) of a multilayer film has been obtained, the number of layers can be corrected according to the fitting relationship and converted into the spectrum of a single-layer film:

[0146] Ab(λ,1)=Ab(λ,L) / mL

[0147] Through the above steps, the multi-layer spectrum can be corrected into a single-layer spectrum. Finally, the spectrum data Si of different aging times are obtained. Usually, the number of features of the spectrum S is related to the number of pixels of the spectrometer detector, and the typical values ​​are 256 and 512;

[0148] Furthermore, 207 pairs of collected spectral data sets {S1, S2, …, S i}Perform principal component analysis to obtain the principal components with the top 95% contribution rate. Using this method, we can obtain the sample spectral data P after dimension reduction. i , compared with S, P i The features are fewer. For this embodiment, P i The number of features is 4, which is more conducive to multiple linear regression modeling analysis.

[0149] Furthermore, 208 a linear regression model is established, in which the input value is {P1, P2, …, P i}, the output is the corresponding value {T s1 ,T s2 ,…,T si}, use the least squares method to solve the bias β0 regression coefficients β1~βm, where m is the number of features after dimensionality reduction. For this embodiment, m=4.

[0150]

[0151] Finally, a quantitative evaluation model for the tensile strength of the sample was obtained.

[0152] During the aging status evaluation phase of the sample to be tested:

[0153] Among them, 209-210 for samples of unknown aging state, the spectrum Sx is collected using the above spectrometer and collection method, and the load vector recorded by principal component analysis is used to obtain the spectrum P after dimension reduction. x Then, the tensile strength T of the polyester film was obtained using the established quantitative evaluation model. sx The test results of the five samples are shown in Table 3.

[0154] Table 3 Test results of the samples to be tested

[0155]

[0156] It can be seen that the test accuracy is more consistent with the tensile strength test method given by the national standard.

[0157] Furthermore, 211-212 passed the sample tensile strength T sxThe tensile strength loss rate of the unaged sample is obtained by comparing it with the tensile strength of the unaged sample. The service life at the operating temperature is obtained by the above analysis. The formula L x / L0=(T s50％ -T sx ) / (T s0 -T s50％ ), and the remaining life L of the polyester film is obtained. x .

[0158] To summarize, firstly, by subjecting the sample polyester film to aging treatment at different temperatures, the service life of the polyester film at a preset temperature is obtained, so that a simulation can be performed in advance, and the ambient temperature of the target polyester film to be tested is simulated by the preset temperature to obtain the initial service life of the target polyester film, thereby avoiding a time-consuming life test; secondly, by collecting near-infrared spectra of the sample polyester film after different degrees of aging treatment, the absorbance of the single-layer polyester film is obtained, and a linear regression analysis is performed on the absorbance and the degree of aging to obtain a quantitative evaluation model for the tensile strength of the polyester film, so that an evaluation model suitable for the target polyester film can be obtained by processing and analyzing the sample polyester film, which can avoid damage to the target polyester film, and finally, the remaining service life of the target polyester film is determined in combination with the service life and the evaluation model, which not only can accurately obtain the remaining service life of the target polyester film to be tested, but also avoids complex operations and reduces the operational requirements of the test.

[0159] Example 3

[0160] Reference Figure 3 , as one embodiment of the present invention, provides a polyester film remaining life assessment system, comprising:

[0161] An acquisition module 301 is used to obtain the variation of the elongation at break of the sample polyester film at different temperatures over time and the tensile strength of the sample at different aging degrees; the sample polyester film is a multi-layer polyester film with a preset thickness;

[0162] Module 302 is constructed to determine the service life of the sample polyester film at a preset temperature according to the change; collect near-infrared spectra of the sample polyester films at multiple different aging degrees to obtain the absorbance of different layers of the target polyester film, and then determine the correlation between the absorbance and the number of layers of the target polyester film; determine the spectral data of the single-layer sample polyester film at different aging degrees according to the correlation, and perform linear regression analysis on the spectral data and the sample tensile strength at the corresponding aging degree to obtain a quantitative evaluation model for the tensile strength of the sample polyester film;

[0163] The determination module 303 is used to determine the target tensile strength of the target polyester film according to the tensile strength quantitative evaluation model, and determine the remaining life of the target polyester film according to the target tensile strength and the service life.

[0164] By using the above-mentioned device, firstly, by subjecting the sample polyester film to aging treatment at different temperatures, the service life of the polyester film at a preset temperature is obtained, so that a simulation can be performed in advance, and the ambient temperature of the target polyester film to be tested is simulated by the preset temperature to obtain the initial service life of the target polyester film, thereby avoiding a time-consuming life test; secondly, by collecting near-infrared spectra of the sample polyester film after aging treatment to different degrees, the absorbance of the single-layer polyester film is obtained, and a linear regression analysis is performed on the absorbance and the aging degree to obtain a quantitative evaluation model for the tensile strength of the polyester film, so that an evaluation model suitable for the target polyester film can be obtained by processing and analyzing the sample polyester film, which can avoid damage to the target polyester film, and finally, the remaining service life of the target polyester film is determined in combination with the service life and the evaluation model, so that not only the remaining service life of the target polyester film to be tested can be accurately obtained, but also complex operations can be avoided, and the operating requirements of the test are reduced, thereby solving the problem of difficulty in evaluating the aging state of the polyester film on site.

[0165] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should be included in the scope of the claims of the present invention.

[0166] Those skilled in the art will appreciate that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can adopt the form of complete hardware embodiments, complete software embodiments, or embodiments in combination with software and hardware. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code. The scheme in the embodiments of the present application can be implemented in various computer languages, for example, object-oriented programming language Java and literal scripting language JavaScript, etc.

[0167] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0168] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0169] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0170] Although the preferred embodiments of the present application have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present application.

[0171] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. A method for evaluating the remaining life of a polyester film, characterized in that: include: Acquire first data and second data of a sample polyester film, and establish a first life acquisition model according to the first data; Preprocessing the second data, and establishing a second tensile strength quantitative evaluation model according to the preprocessed second data; The remaining life of the polyester film to be tested is determined according to the first life acquisition model and the second tensile strength quantitative evaluation model.

2. The method for evaluating the remaining life of a polyester film according to claim 1, wherein: The preprocessing of the second data comprises: Obtain the absorbance of different layers of sample polyester film; Determine the correlation between the absorbance of the sample polyester film and the number of layers; The sample polyester film is a multi-layer polyester film with a preset thickness.

3. The method for evaluating the remaining life of a polyester film according to claim 2, wherein: The establishing of a first life acquisition model according to the first data comprises: Determine the variation law of the test life of the sample polyester film with temperature according to the first data; A first life acquisition model is established based on the variation rule to determine the sample polyester film at a preset temperature.

4. The method for evaluating the remaining life of a polyester film according to claim 3, wherein: The method of obtaining the absorbance of different layers of the sample polyester film comprises: Determine the wavelength of the near-infrared spectrum according to the characteristic absorption peak of the sample polyester film, and set the backing material according to the application environment of the sample polyester film to construct a near-infrared spectrum collection environment; Based on the near-infrared spectrum collection environment, a diffuse reflection collection method is used to collect the absorbance of different layers of the sample polyester film.

5. The method for evaluating the remaining life of a polyester film according to claim 4, wherein: Determining the remaining life of the polyester film to be tested according to the first life acquisition model and the second tensile strength quantitative evaluation model comprises: The tensile strength of the polyester film to be tested and the tensile strength of the unaged sample polyester film are obtained by using a second tensile strength quantitative evaluation model; The tensile strength loss rate of the polyester film to be tested is obtained by comparing the tensile strength of the polyester film to be tested with the tensile strength of the unaged sample polyester film; The remaining life of the polyester film to be tested is obtained by the tensile strength loss rate of the polyester film to be tested and the service life of the polyester film to be tested obtained by the first life acquisition model.

6. The method for evaluating the remaining life of a polyester film according to claim 5, wherein: The preprocessing of the second data further includes: Determine the spectral data of the single-layer sample polyester film at different aging degrees according to the correlation; A linear regression analysis is performed on the spectral data and the tensile strength of the samples at the corresponding aging degrees to obtain a quantitative evaluation model for the second tensile strength of the sample polyester film.

7. The method for evaluating the remaining life of a polyester film according to claim 6, wherein: The preprocessing of the second data further includes: Performing dimension reduction processing on the spectral data by principal component analysis to obtain spectral data after dimension reduction; A linear regression model was established, in which the input was the spectral data after dimension reduction, and the output was the tensile strength of the sample at the corresponding aging degree. The least squares method was used to solve it and the second tensile strength quantitative evaluation model was obtained.

8. A polyester film remaining life assessment system, characterized in that: include: An acquisition module, used for acquiring first data and second data of the sample polyester film, and establishing a first life acquisition model according to the first data; A construction module, used for preprocessing the second data and establishing a second tensile strength quantitative evaluation model according to the preprocessed second data; A determination module is used to determine the remaining life of the polyester film to be tested according to the first life acquisition model and the second tensile strength quantitative evaluation model.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 7 are implemented.

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