A method for analyzing stress changes in optical fiber capillaries

Abstract

The invention relates to the field of optical fiber technology, and specifically discloses a method for analyzing stress changes in optical fiber capillaries, comprising: obtaining strain values, calculating stress deviation values ​​and determining stress mutation points by a moving window method; analyzing the consistency of stress mutations at each monitoring point; if not, judging whether the stress mutation point is a plastic yield point, and if so, analyzing its stress mutation time and generating a plastic analysis signal; judging whether the yield analysis point produces a diffusion effect and accelerates plastic change based on the plastic analysis signal; if the plastic change is accelerated, constructing a plastic prediction model based on historical data to predict the time when cracks appear in the optical fiber capillaries; the method can effectively quantify stress mutations, timely discover local stress anomalies, evaluate plastic changes and predict the time when cracks appear, and improve the monitoring and analysis capabilities of stress changes in optical fiber capillaries.

Description

Technical Field

[0001] The invention relates to the technical field of optical fiber, and in particular to an analysis method for optical fiber capillary stress changes. Background Art

[0002] A Chinese invention patent with publication number CN113959838B discloses a method for monitoring stress of optical fiber capillaries, including: storing initial values ​​of stress changes, tracking and analyzing stage-by-stage stresses, obtaining microplastic strain stresses, obtaining elastic stress deformation values, analyzing stress values ​​in the plastic hardening stage, monitoring deformation stress points and network feedback of stress data values; monitoring deformation stress points. During the elastic force recording process of the optical fiber capillary, the deformation stress points generated can be monitored by electronic instruments, and the data change values ​​of the stress points are recorded, so that the deformation value of the optical fiber capillary can be monitored every time a range degree is changed, thereby monitoring the deformation limit of the optical fiber capillary; network feedback of stress data values. The stress change value generated by the optical fiber capillary can be recorded by a storage module, and then transmitted to the control end through a network module for network calculation and monitoring, thereby qualitatively and quantitatively analyzing the stress of the optical fiber capillary.

[0003] The existing technology does not conduct quantitative analysis on the stress mutation of optical fiber capillaries, and it is difficult to grasp the stress mutation situation. The existing technology only records the data change value by monitoring the deformation stress point, and cannot accurately know the consistency of the stress mutation of each monitoring point in terms of time and stress deviation value, resulting in the inability to timely discover the local stress abnormality problem, affecting the stability and reliability of the optical fiber capillary; if the method of constructing the stress absolute difference sequence and the time absolute difference sequence is adopted, and the stress consistency coefficient is calculated to quantify the stress mutation situation, it can provide a solid data foundation for subsequent in-depth analysis, timely capture the local stress abnormality, and reduce the possibility of serious damage caused by the local stress abnormality.

[0004] The existing technology does not determine whether the stress mutation point is the plastic yield point, and it is difficult to accurately grasp the turning point from elastic deformation to plastic deformation of the optical fiber capillary. This makes it lack of basis when evaluating the stability and reliability of the optical fiber capillary under different stress conditions, which may lead to misjudgment of the mechanical properties of the optical fiber capillary. If the stress mutation point is verified by using Hooke's law and comparing the theoretical stress deviation value with the actual measured value, the plastic yield point can be determined, which provides a strong basis for evaluating the changes in the mechanical properties of the optical fiber capillary and better grasps its stability and reliability under different stress conditions.

[0005] The existing technology does not conduct an in-depth analysis of the trend of plastic changes, nor can it predict the time when cracks will appear in the optical fiber capillary. The existing technology can only monitor the stress change value and provide network feedback, but cannot predict whether the plastic change will accelerate and when cracks will appear. If, after determining the plastic yield point, it is further analyzed whether the yield analysis point produces a diffusion effect and whether it accelerates the plastic change, and a plastic prediction model is constructed based on historical data, it is possible to predict the development trend of the plastic change, take measures in advance to slow down or prevent the deterioration of the plastic change, predict the time when cracks will appear in the optical fiber capillary, and improve the safety and stability of the optical fiber system.

[0006] To this end, the present invention provides a method for analyzing changes in optical fiber capillary stress. Summary of the invention

[0007] The object of the present invention is to provide a method for analyzing the capillary stress variation of an optical fiber to solve the above-mentioned problems.

[0008] The purpose of the present invention can be achieved through the following technical solutions:

[0009] A method for analyzing changes in capillary stress of an optical fiber comprises the following steps:

[0010] Analyze the stress change curves of multiple monitoring points of the optical fiber capillary to obtain stress mutation points;

[0011] Analyze the stress mutation points to determine whether the stress mutation at each monitoring point is consistent;

[0012] If they are inconsistent, determine whether the stress mutation point is a plastic yield point. If so, analyze the stress mutation time of the plastic mutation point, determine the yield analysis point and generate a plastic analysis signal.

[0013] Based on the plasticity analysis signal, determine whether the yield analysis point produces a diffusion effect, and if so, determine whether the yield analysis point accelerates the plasticity change of the optical fiber capillary;

[0014] If it will accelerate the plastic change of the optical fiber capillary, a plasticity prediction model is constructed based on historical data to predict the time when cracks appear in the optical fiber capillary.

[0015] As a further technical solution of the present invention: the stress mutation point is determined by:

[0016] Calculate the change deviation between the strain force at each monitoring point and the strain force in the initial state to obtain the stress deviation value;

[0017] By applying different external forces to the optical fiber capillary step by step, the stress deviation value of the change of the monitoring point of the optical fiber capillary is obtained, the external force-stress change curve is drawn, and the stress change sequence is constructed;

[0018] Based on the stress change sequence, the stress mutation point is determined through numerical analysis.

[0019] As a further technical solution of the present invention: the method of determining the stress mutation point through numerical analysis is:

[0020] The moving window method is used to divide the stress change sequence into multiple windows, and the kurtosis of the stress change sequence in each window is calculated;

[0021] The kurtosis change rate of two adjacent windows is calculated, and the maximum value point of the stress deviation value in the window that is initially higher than the preset kurtosis change threshold is obtained as the stress mutation point.

[0022] As a further technical solution of the present invention: the method for judging whether the stress mutation of each monitoring point is consistent is:

[0023] Obtain stress mutation time of multiple monitoring points of the optical fiber capillary, calculate the absolute difference of stress mutation time of any two monitoring points, and construct a time absolute difference sequence;

[0024] Calculate the absolute difference of stress deviation values ​​corresponding to stress mutation points of any two monitoring points and construct a stress absolute difference sequence;

[0025] The stress consistency coefficient is determined by a weighted formula based on the time absolute difference sequence and the stress absolute difference sequence;

[0026] If the stress consistency coefficient is lower than the preset consistency threshold, it is considered that the stress mutation of the entire optical fiber capillary is inconsistent.

[0027] As a further technical solution of the present invention: the plastic yield point is determined as follows:

[0028] If the external force-stress change before the stress mutation point satisfies Hooke's law, and the external force-stress change after the stress mutation point does not satisfy Hooke's law, then the stress mutation point is the plastic yield point.

[0029] The time of the plastic yield point is analyzed to generate a plastic analysis signal.

[0030] As a further technical solution of the present invention: the plasticity analysis signal is generated in the following manner:

[0031] Obtain the stress mutation time when multiple monitoring points of the optical fiber capillary become plastic yield points, sort them according to time, and determine the yield analysis point;

[0032] If the stress mutation time at the yield analysis point does not meet expectations, a plastic analysis signal is generated.

[0033] As a further technical solution of the present invention: the method for determining whether the yield analysis point produces a diffusion effect is:

[0034] Based on the plastic analysis signal, within the monitoring period, determine whether there are continuous plastic yield points adjacent to the yield analysis point;

[0035] If it occurs, the continuous plastic yield point is quantitatively analyzed to obtain the strain-time ratio and continuous yield ratio;

[0036] The continuous effect value is calculated by summing the strain-time ratio and the continuous yield ratio through the formula;

[0037] By comparing the continuous effect value with the preset continuous effect threshold, it is determined that the yield analysis point produces a diffusion effect.

[0038] As a further technical solution of the present invention: the continuous yield ratio and the mean value of strain time are obtained by:

[0039] Starting from the yield analysis point, calculate the difference in stress mutation time between two adjacent plastic yield points to obtain the strain time difference;

[0040] Obtain the average of the strain time differences of the plastic yield points at all adjacent positions to obtain the strain time average;

[0041] The strain time ratio is obtained by performing a ratio processing on the mean strain time and the total strain time difference;

[0042] Obtain the number of all plastic yield points and the number of continuous plastic yield points within the monitoring period;

[0043] The continuous yield ratio is obtained by ratioing the number of continuous plastic yield points to the number of all plastic yield points.

[0044] As a further technical solution of the present invention: whether the yield analysis point will accelerate the plastic change of the optical fiber capillary is determined as follows:

[0045] Based on the strain time difference between two plastic yield points, a continuous time difference series is constructed;

[0046] Calculate the Pearson correlation coefficient of the continuous time difference series and compare and analyze the Pearson correlation coefficient;

[0047] If the strain time difference shows a downward trend, it is believed that the yield analysis point will accelerate the plastic change of the optical fiber capillary.

[0048] As a further technical solution of the present invention: the prediction method of the time when the crack appears in the optical fiber capillary is:

[0049] If the plastic change of the optical fiber capillary is accelerated, a large amount of time when cracks appear at the plastic yield point is obtained from the historical data of the optical fiber capillary, and a plastic prediction data set is constructed;

[0050] Based on the plasticity prediction data set, the support vector machine algorithm is used to build a plasticity prediction model and output the predicted crack time of the plasticity analysis point.

[0051] Beneficial effects of the present invention:

[0052] (1) By constructing the stress absolute difference series and the time absolute difference series, the abstract stress mutation situation is converted into a specific and analyzable numerical series, and the consistency of the stress mutation in time and stress deviation value of each monitoring point of the optical fiber capillary can be quantified, providing a solid data basis for subsequent in-depth analysis and avoiding the ambiguity and subjectivity of the previous assessment of the stress mutation of the optical fiber capillary. By analyzing the consistency of the stress mutation, the synchronization and similarity of the stress mutation of each monitoring point of the optical fiber capillary can be judged, and the possible local stress abnormality of the optical fiber capillary can be captured, which helps to take timely measures to reduce the possibility of serious damage caused by local stress abnormality.

[0053] (2) Hooke's law is used to verify the stress mutation point. By comparing the theoretical stress deviation value and the actual measured value, it can be determined whether the stress mutation point is the plastic yield point. This provides a basis for understanding the changes in the mechanical properties of the optical fiber capillary and helps to grasp the turning point from elastic deformation to plastic deformation of the optical fiber capillary, thereby evaluating its stability and reliability under different stress conditions.

[0054] (3) After determining the plastic yield point, we further analyze whether the yield analysis point produces a diffusion effect and whether it will accelerate plastic change. By calculating the continuous effect value and the Pearson linear correlation coefficient, we can effectively predict the development trend of plastic change, providing strong support for taking measures in advance to slow down or prevent the deterioration of plastic change. Using the support vector machine algorithm, we build a plastic prediction model based on a large amount of historical data, which can predict the time when cracks appear in the optical fiber capillary, thereby improving the safety and stability of the optical fiber system. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 It is a flow chart of the stress change analysis method of the present invention. DETAILED DESCRIPTION

[0056] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the present invention. Based on the implementation method in the present invention, all other implementation methods obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present invention.

[0057] See also Figure 1 As shown, the present invention is a method for analyzing changes in optical fiber capillary stress, comprising the following steps:

[0058] Step 1, analyzing the stress change curves of multiple monitoring points of the optical fiber capillary to obtain stress mutation points;

[0059] In some embodiments, a fiber grating sensor is used to obtain a plurality of monitoring points, and the strain value generated by the deformation of the optical fiber capillary under force is obtained to obtain the strain force;

[0060] Calculate the change deviation between the strain force at each monitoring point and the strain force in the initial state to obtain the stress deviation value;

[0061] It should be noted that, in some embodiments, the optical fiber capillary is placed on a clamping member and connected to an electronic instrument to feedback stress changes to obtain the strain force in the initial state;

[0062] By applying different external forces to the optical fiber capillary step by step, the stress deviation value of the change of the monitoring point of the optical fiber capillary is obtained, and the external force is used as the X-axis and the stress deviation value is used as the Y-axis to draw the external force-stress change curve, and construct the stress change sequence;

[0063] The moving window method is used to divide the stress change sequence into multiple windows, and the kurtosis of the stress change sequence in each window is calculated;

[0064] Calculate the kurtosis change rate of two adjacent windows, and compare it with the preset kurtosis change threshold, to determine the window that is initially higher than the kurtosis change threshold in the stress change sequence;

[0065] Obtain the maximum value of the stress deviation value in the window that is initially higher than the kurtosis change threshold as the stress mutation point;

[0066] It should be noted that the role of determining the stress mutation point is: Role 1: timely discover local stress anomalies. By analyzing the stress mutation point, constructing the stress absolute difference series and the time absolute difference series, and calculating the stress consistency coefficient, the stress mutation situation can be quantified, and the possible local stress anomalies of the optical fiber capillary can be detected in time;

[0067] Function 2: To judge the change of mechanical properties of materials and compare the theoretical stress deviation value with the actual measured value, it can be determined whether the stress mutation point is the plastic yield point. This helps to understand the change of mechanical properties of optical fiber capillaries, grasp the turning point from elastic deformation to plastic deformation, and then evaluate its stability and reliability under different stress conditions.

[0068] Step 2: Analyze the stress mutation points to determine whether the stress mutation at each monitoring point is consistent;

[0069] Obtain the stress mutation time of multiple monitoring points of the optical fiber capillary and calculate the absolute difference of the stress mutation time between any two monitoring points i and j , where t i ,t jrespectively represent the stress mutation times of monitoring points i and j, where 1 ≤ i < j ≤ n, and n is the total number of monitoring points;

[0070] Based on the absolute difference of the stress mutation times of any two monitoring points , construct an absolute time difference sequence;

[0071] Obtain the stress deviation values corresponding to the stress mutation points of all monitoring points, calculate the absolute difference of the stress deviation values corresponding to the stress mutation points of any two monitoring points, and construct a stress absolute difference sequence;

[0072] It should be noted that the stress mutation time refers to the time from the start monitoring time of the monitoring point to the stress mutation point;

[0073] Through the formula: Obtain the stress consistency coefficient I, where T and S are the sums of the absolute time difference sequence and the stress absolute difference sequence respectively, and T max 、S max are the maximum absolute differences in the absolute time difference sequence and the stress absolute difference sequence respectively, and α and β take 1.25 and 1.71 respectively;

[0074] Compare the stress consistency coefficient with a preset consistency threshold. If the stress consistency coefficient is higher than the preset consistency threshold, it is considered that the stress mutations of the overall optical fiber capillary are consistent;

[0075] If the stress consistency coefficient is lower than the preset consistency threshold, it is considered that the stress mutations of the overall optical fiber capillary are inconsistent;

[0076] It should be noted that the role of analyzing whether the stress mutations of the overall optical fiber capillary are consistent is as follows:

[0077] Role 1: Quantify the stress mutation situation. By constructing the stress absolute difference sequence and the absolute time difference sequence, the originally abstract stress mutation situation is transformed into a quantifiable and analyzable numerical sequence, providing a data basis for subsequent consistency evaluation;

[0078] Role 2: Judge the overall stress mutation state, reflecting whether the monitoring points of the optical fiber capillary are relatively synchronous or similar in terms of the stress mutation time and stress deviation value, which is conducive to timely discovering problems such as local abnormal stress on the optical fiber capillary;

[0079] Role 3: Comprehensive evaluation of consistency: Comprehensively evaluate the stress mutation consistency of each monitoring point of the optical fiber capillary in terms of time and stress, and can reflect the consistency of the stress mutation analysis of the optical fiber capillary from multiple dimensions.

[0080] Step 3: If they are inconsistent, determine whether the stress mutation point is a plastic yield point. If so, analyze the stress mutation time of the plastic mutation point, determine the yield analysis point and generate a plastic analysis signal;

[0081] In some embodiments, the deformation of the optical fiber capillary caused by the external force is divided into elastic deformation and plastic deformation;

[0082] It should be noted that elastic deformation refers to the fact that when the optical fiber capillary is stretched by a small external force, the distance between the atoms inside it will change slightly, causing the optical fiber to have a certain elongation and deformation. As long as the external force does not exceed the elastic limit of the optical fiber material, when the external force is removed, the force between the atoms will cause the atoms to return to their original positions, and the optical fiber capillary will be able to restore to its original length and shape;

[0083] Plastic deformation means that if the external force applied to the optical fiber capillary is too large and exceeds its elastic limit, the atomic structure inside the optical fiber will undergo irreversible changes. For example, in the process of manufacturing optical fiber capillaries, if the drawing process parameters are not properly controlled and the applied pulling force is too large, the optical fiber may undergo plastic deformation during the drawing process. At this point, even if no external force is applied later, the optical fiber cannot return to its original state, and its diameter, length, and internal structure may undergo permanent changes.

[0084] In some embodiments, by verifying the stress mutation point using Hooke's law, a difference analysis is performed between a theoretical stress deviation value calculated using Hooke's law and a stress deviation value actually measured to determine whether the external force-stress change before the stress mutation point satisfies Hooke's law;

[0085] It should be noted that in the elastic stage, the stress and strain of the material are proportional. Following Hooke's law, the stress of several monitoring points before the stress mutation point is selected to calculate the ratio of stress to strain at these points. If these ratios are approximately a constant, that is, the elastic modulus of the material, it means that the material is basically in an elastic state before these points and no plastic deformation occurs;

[0086] If the external force-stress change before the stress mutation point satisfies Hooke's law, and the external force-stress change after the stress mutation point does not satisfy Hooke's law, then the stress mutation point is the plastic yield point;

[0087] Obtain the stress mutation time when multiple monitoring points of the optical fiber capillary become plastic yield points, sort them from small to large according to the time values, and select the plastic yield point with the smallest time value as the yield analysis point;

[0088] Compare the stress mutation time at the yield analysis point with the preset expected time;

[0089] If the stress mutation time at the yield analysis point is lower than the preset expected time, an early warning is sent to the system; otherwise, a plastic analysis signal is generated.

[0090] Step 4: Based on the plasticity analysis signal, determine whether the yield analysis point produces a diffusion effect. If so, determine whether the yield analysis point accelerates the plastic change of the optical fiber capillary.

[0091] Based on the plastic analysis signal, within the monitoring period, determine whether there are continuous plastic yield points adjacent to the yield analysis point;

[0092] It should be noted that if the monitoring point at the position adjacent to the yield analysis point of the optical fiber capillary is also a plastic yield point, then the plastic yield point and the yield analysis point at the adjacent position are considered to be continuous;

[0093] Specifically, it is determined whether adjacent plastic yield points are continuous in the time dimension;

[0094] The time when the yield analysis point is determined to be the plastic yield point is taken as the starting time of continuous monitoring;

[0095] Starting from the starting time, if the monitoring points at the adjacent positions of the plastic yield point are successively determined as plastic yield points according to the distribution of positions as time goes by, then whether the adjacent plastic yield points are continuous in the time dimension;

[0096] Starting from the yield analysis point, calculate the difference in stress mutation time between two adjacent plastic yield points to obtain the strain time difference;

[0097] Obtain the average of the strain time differences of the plastic yield points at all adjacent positions to obtain the strain time average;

[0098] The strain time ratio is obtained by performing a ratio processing on the mean strain time and the total strain time difference;

[0099] Obtain the number of all plastic yield points and the number of continuous plastic yield points within the monitoring period;

[0100] The continuous yield ratio is obtained by ratioing the number of continuous plastic yield points to the number of all plastic yield points.

[0101] Based on the strain-time ratio and the continuous yield ratio, the continuous effect value is obtained by summing the formula;

[0102] If the continuation effect value is higher than the preset continuation effect threshold, it is considered that the yield analysis point produces a diffusion effect;

[0103] It should be noted that the role of judging whether the yield analysis point produces a diffusion effect is as follows: Role 1: Evaluating the trend of plastic change: By judging whether the yield analysis point produces a diffusion effect, evaluating the development trend of plastic change, judging whether the plastic deformation of the optical fiber capillary will accelerate deterioration, and providing a basis for taking effective measures in advance;

[0104] Function 2: Ensure the safe and stable operation of the optical fiber system: The diffusion effect is closely related to the risk of cracks in the optical fiber capillary. By judging the diffusion effect, the health of the optical fiber capillary can be predicted and possible faults can be warned in advance.

[0105] If the continuous effect value is lower than or equal to the preset continuous effect threshold, the yield analysis point is not considered to have a diffusion effect, but the change of the continuous effect value needs to be continuously monitored;

[0106] If the yield analysis point produces a diffusion effect, the time when the yield analysis point is determined to be a plastic yield point is taken as the starting point of the analysis time, and the strain time difference between two adjacent plastic yield points in the continuous plastic yield points is obtained;

[0107] Based on the strain time difference between two plastic yield points, a continuous time difference series is constructed;

[0108] The Pearson linear correlation coefficient r of the continuous time difference series is calculated by the Pearson correlation coefficient calculation formula;

[0109] If the Pearson correlation coefficient r of the continuous time difference series is within the preset correlation range, that is, the strain time difference shows a downward trend, it is believed that the yield analysis point will accelerate the plastic change of the optical fiber capillary.

[0110] Step 5: If the plastic change of the optical fiber capillary is accelerated, a plastic prediction model is constructed based on historical data to predict the time when cracks appear in the optical fiber capillary;

[0111] If the plastic change of the optical fiber capillary is accelerated, a large amount of time when cracks appear at the plastic yield point is obtained from the historical data of the optical fiber capillary, and a plastic prediction data set is constructed;

[0112] Use the support vector machine algorithm to build a plasticity prediction model and output the predicted crack time of the plasticity analysis point;

[0113] It should be noted that the support vector machine (SVM) is used to build a plastic prediction model for optical fiber capillaries. The crack time and related characteristic data of the plastic yield point are obtained from historical data, cleaned and normalized. The Gaussian kernel function is selected according to the characteristics of the data, and the optimal parameter combination of the penalty parameter C is determined by cross-validation to build the model. The training set and the test set are divided into 8:2, and the model is trained with the training set and the solution parameters are optimized. Then, the mean square error and mean absolute error indicators are used to evaluate the accuracy and generalization ability of the model based on the test set.

[0114] Based on the plasticity prediction model, the predicted crack time of the plasticity analysis point is output.

[0115] The technical solution of the specific implementation of the present invention is: by constructing a stress absolute difference sequence and a time absolute difference sequence, the abstract stress mutation situation is converted into a specific analyzable numerical sequence, and the consistency of the stress mutation of each monitoring point of the optical fiber capillary in terms of time and stress deviation value can be quantified, providing a solid data foundation for subsequent in-depth analysis, and avoiding the ambiguity and subjectivity of the previous evaluation of the stress mutation of the optical fiber capillary;

[0116] By analyzing the consistency of stress mutation, the synchronization and similarity of each monitoring point of the optical fiber capillary during stress mutation can be determined, and the possible abnormal local stress of the optical fiber capillary can be captured, which helps to take timely measures to reduce the possibility of serious damage caused by abnormal local stress.

[0117] Hooke's law is used to verify the stress mutation point. By comparing the theoretical stress deviation value and the actual measured value, it can be determined whether the stress mutation point is the plastic yield point, which provides a basis for understanding the change in the mechanical properties of the optical fiber capillary and helps to grasp the turning point from elastic deformation to plastic deformation of the optical fiber capillary, thereby evaluating its stability and reliability under different stress conditions. After determining the plastic yield point, it is further analyzed whether the yield analysis point produces a diffusion effect and whether it will accelerate the plastic change. By calculating the continuous effect value and the Pearson linear correlation coefficient, the development trend of the plastic change can be effectively predicted, providing strong support for taking measures in advance to slow down or prevent the deterioration of the plastic change.

[0118] By using the support vector machine algorithm and building a plasticity prediction model based on a large amount of historical data, the time when cracks will appear in the optical fiber capillary can be predicted, thus improving the safety and stability of the optical fiber system.

[0119] The above is a detailed description of an embodiment of the present invention, but the content is only a preferred embodiment of the present invention and cannot be considered to limit the scope of implementation of the present invention. All equivalent changes and improvements made according to the scope of application of the present invention should still fall within the scope of the present invention.

Claims

1. A method for analyzing changes in capillary stress of an optical fiber, characterized in that: The following methods are included: Analyze the stress change curves of multiple monitoring points of the optical fiber capillary to obtain stress mutation points; Analyze the stress mutation points to determine whether the stress mutation at each monitoring point is consistent; The method for judging whether the stress mutation of each monitoring point is consistent is as follows: Obtain stress mutation time of multiple monitoring points of the optical fiber capillary, calculate the absolute difference of stress mutation time of any two monitoring points, and construct a time absolute difference sequence; Calculate the absolute difference of stress deviation values ​​corresponding to stress mutation points of any two monitoring points and construct a stress absolute difference sequence; Based on the time absolute difference series and stress absolute difference series, the stress consistency coefficient is determined by a weighted formula; If the stress consistency coefficient is lower than the preset consistency threshold, it is considered that the stress mutation of the entire optical fiber capillary is inconsistent; If they are inconsistent, determine whether the stress mutation point is a plastic yield point. If so, analyze the stress mutation time of the plastic yield point, determine the yield analysis point and generate a plastic analysis signal. Based on the plasticity analysis signal, determine whether the yield analysis point produces a diffusion effect, and if so, determine whether the yield analysis point accelerates the plasticity change of the optical fiber capillary; If it will accelerate the plastic change of the optical fiber capillary, a plasticity prediction model is constructed based on historical data to predict the time when cracks will appear in the optical fiber capillary.

2. The method for analyzing the capillary stress change of an optical fiber according to claim 1, characterized in that: The stress mutation point is determined as follows: Calculate the change deviation between the strain force at each monitoring point and the strain force in the initial state to obtain the stress deviation value; By applying different external forces to the optical fiber capillary step by step, the stress deviation value of the change of the monitoring point of the optical fiber capillary is obtained, the external force-stress change curve is drawn, and the stress change sequence is constructed; Based on the stress change sequence, the stress mutation point is determined through numerical analysis.

3. The method for analyzing the capillary stress change of an optical fiber according to claim 2, characterized in that: The method of determining the stress mutation point through numerical analysis is as follows: The moving window method is used to divide the stress change sequence into multiple windows, and the kurtosis of the stress change sequence in each window is calculated; The kurtosis change rate of two adjacent windows is calculated, and the maximum value point of the stress deviation value in the window that is initially higher than the preset kurtosis change threshold is obtained as the stress mutation point.

4. The method for analyzing the capillary stress change of an optical fiber according to claim 1, characterized in that: The plastic yield point is determined as follows: If the external force-stress change before the stress mutation point satisfies Hooke's law, and the external force-stress change after the stress mutation point does not satisfy Hooke's law, then the stress mutation point is the plastic yield point; The time of the plastic yield point is analyzed to generate a plastic analysis signal.

5. The method for analyzing the capillary stress change of an optical fiber according to claim 4, characterized in that: The plasticity analysis signal is generated as follows: Obtain the stress mutation time when multiple monitoring points of the optical fiber capillary become plastic yield points, sort them according to time, and determine the yield analysis point; If the stress mutation time at the yield analysis point does not meet expectations, a plastic analysis signal is generated.

6. The method for analyzing the capillary stress change of an optical fiber according to claim 1, characterized in that: The method for determining whether the yield analysis point produces a diffusion effect is as follows: Based on the plastic analysis signal, during the monitoring period, determine whether there are continuous plastic yield points adjacent to the yield analysis point; If it occurs, the continuous plastic yield point is quantitatively analyzed to obtain the strain-time ratio and continuous yield ratio; The continuous effect value is calculated by summing the strain-time ratio and the continuous yield ratio through the formula; By comparing the continuous effect value with the preset continuous effect threshold, it is determined that the yield analysis point produces a diffusion effect.

7. The method for analyzing the capillary stress change of an optical fiber according to claim 6, characterized in that: The continuous yield ratio and strain time ratio are obtained as follows: Starting from the yield analysis point, calculate the difference in stress mutation time between two adjacent plastic yield points to obtain the strain time difference; Obtain the average of the strain time differences of the plastic yield points at all adjacent positions to obtain the strain time average; The strain time ratio is obtained by performing a ratio processing on the mean strain time and the total strain time difference; Obtain the number of all plastic yield points and the number of continuous plastic yield points within the monitoring period; The continuous yield ratio is obtained by ratioing the number of continuous plastic yield points to the number of all plastic yield points.

8. The method for analyzing the capillary stress change of an optical fiber according to claim 1, characterized in that: The method for judging whether the yield analysis point will accelerate the plastic change of the optical fiber capillary is: Based on the strain time difference between two plastic yield points, a continuous time difference series is constructed; Calculate the Pearson correlation coefficient of the continuous time difference series and compare and analyze the Pearson correlation coefficient; If the strain time difference shows a downward trend, it is believed that the yield analysis point will accelerate the plastic change of the optical fiber capillary.

9. The method for analyzing the capillary stress change of an optical fiber according to claim 1, characterized in that: The method for predicting the time when the optical fiber capillary crack appears is: If the plastic change of the optical fiber capillary is accelerated, a large amount of time when cracks appear at the plastic yield point is obtained from the historical data of the optical fiber capillary, and a plastic prediction data set is constructed; Based on the plasticity prediction data set, the support vector machine algorithm is used to build a plasticity prediction model and output the predicted crack time of the plasticity analysis point.

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