CN115127912A - Composite cable joint fatigue fracture life evaluation method based on multi-source information fusion - Google Patents
Composite cable joint fatigue fracture life evaluation method based on multi-source information fusion Download PDFInfo
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Abstract
The invention discloses a composite cable joint fatigue fracture life evaluation method based on multi-source information fusion, belongs to the technical field of high voltage and insulation, and aims to solve the problem that a special test evaluation method is lacked in composite cable joint fatigue fracture accidents, and the service life of the composite cable joint fatigue fracture accidents cannot be accurately predicted. The method comprises the steps of sample and test equipment preparation, sample test and data acquisition, data processing and fracture interference model building result application. The invention integrates the joint fracture accidents which are easy to happen in the actual working condition, analyzes the factors which influence the cable joint fracture by integrating the temperature, the humidity and the stretching degree, constructs the fracture interference model, realizes the health condition evaluation of the cable joint, judges the reasonable fracture degree, prevents the crack from continuing to expand, and ensures the safe work of the cable joint.
Description
Technical Field
The invention belongs to the technical field of high voltage and insulation, and particularly relates to a composite cable joint fatigue fracture life evaluation method based on multi-source information fusion.
Background
The power cable works in a complex environment for a long time, the performance of the cable suit is reduced along with the aging of a line, and the safe operation of a power grid is threatened. Among them, XLPE cable is called cross-linked polyethylene cable, and the cable plays an extremely important role in power supply network. In long-term operation, the joint of the cable is one of the weakest links in a cable line and is easy to generate faults under the influence of factors such as complex operation conditions, variable external environments, sudden external force damage and the like. Typical fault defects include high temperature aging, moisture exposure, delamination, cracking, air gaps, water tree branches, partial discharge, electrical breakdown, and the like. Necessary and appropriate means are required to monitor the operation of the joint to prevent accidents.
In a power distribution network system, main research objects include conventional state evaluation, withstand voltage test, and partial discharge detection. In the prior art, the overhaul modes of the power distribution network in China mainly comprise accident overhaul, planned overhaul and emerging nondestructive online detection. The nondestructive online detection has the characteristics of low detection cost, low implementation, installation and debugging difficulty, capability of effectively reducing the accident occurrence rate and the like, and becomes an important research object in recent years. And the terahertz nondestructive detection in the nondestructive detection has high time domain spectrum signal-to-noise ratio, and is very suitable for imaging application.
At present, relevant research is carried out aiming at the service state and prediction of a cable, comprehensive experimental research of multi-source information is still lacked, evaluation and early warning are carried out on the operation state of a cable joint of a power distribution network in patent application CN202111518571.0 & ltan evaluation and early warning device and method for the operation state of the cable joint of the power distribution network & lta & gt power saving company & lta & gt in China, Gansu & lta & gt, China, and China, in the patent application CN202111518571.0 & ltan evaluation and early warning device and method for the operation state of the cable joint of the power distribution network & lta & gt, wherein an evaluation and early warning method for guiding characteristic data, such as the discharge amount, the temperature rise and the humidity of the cable joint, which can represent the operation state of the cable joint is disclosed.
Based on the background technology, research and development personnel provide a fatigue fracture life evaluation method for a composite cable joint with multi-source information fusion by synthesizing joint fracture accidents which are easy to occur in actual working conditions.
Disclosure of Invention
The invention aims to provide a composite cable joint fatigue fracture life assessment method based on multi-source information fusion, and aims to solve the problem that the composite cable joint fatigue fracture accident lacks a special test assessment method and the life of the composite cable joint fatigue fracture accident cannot be accurately predicted.
In order to solve the problems, the technical scheme of the invention is as follows:
the composite cable joint fatigue fracture life evaluation method based on multi-source information fusion comprises the following steps:
s1, preparing a sample and test equipment;
s1.1, preparing a sample;
preparing a complete XLPE cable joint as a test sample, and classifying the defect and fracture defects of the cable joint into three grades of defect-free, micro-crack defect and severe-crack defect, wherein: the depth of the micro crack is within 1cm, and the length of the crack is within 2 cm; the severe crack is more than 1cm in depth and more than 2cm in length;
s1.2, preparing an automatic temperature and humidity control test box;
s1.3, preparing tensile test equipment;
s1.4, preparing terahertz detection test equipment;
s2, sample testing and data acquisition;
the image acquisition and data processing system applies Word files, Excel files, Visio files, BMP files and MATLAB simulation software in the prior art;
s2.1, collecting tensile test data and carrying out terahertz detection on the tested sample to obtain a time domain spectrogram;
s2.2, collecting high-temperature test data and carrying out terahertz detection on the tested sample to obtain a time domain spectrogram;
s2.3, stretching the sample subjected to the high-temperature test in the S2.2 again, and collecting test data; carrying out terahertz detection on the sample after the tensile test to obtain a time domain spectrogram;
s2.4, collecting high-temperature and damp test data and carrying out terahertz detection on the tested sample to obtain a time domain spectrogram;
s2.5, stretching the sample subjected to the high-temperature and damp test in the S2.4 again, and collecting test data; carrying out terahertz detection on the sample after the tensile test to obtain a time domain spectrogram;
s3, processing data;
carrying out Word arrangement and Visio mapping analysis on the data acquired in S2.1-S2.5, carrying out MATLAB data conversion according to the acquired data, and carrying out data comparison reference on the stretched experimental sample and the unstretched experimental sample;
obtaining terahertz transmission and reflection coefficients through a terahertz time-domain spectrogram, and further calculating the complex dielectric constant of the sample;
s4, establishing a fracture interference model;
when a component containing a crack or an initial defect bears steady-state random cyclic stress, in order to ensure the safe operation of the component, the stress intensity factor variation range is controlled below a fatigue crack propagation threshold value so as to prevent the crack from continuing to propagate;
therefore, a stress intensity factor variation range and a fatigue crack propagation threshold value are obtained by relying on data in S3, and a fracture interference model is established;
s5, applying the result;
and performing terahertz detection on the cable joint in actual operation to obtain the defect condition of the XLPE cable joint sample, substituting the defect condition into the fracture interference model established in S4, estimating a reasonable fracture degree, preventing the crack from continuing to expand and ensuring the safe operation of the crack.
Further, the temperature and humidity automatic control test box in the step S1.2 is a high-voltage electrothermal test box (I) with adjustable temperature and controllable humidity, a copper hook is installed inside the test box for conducting electricity, and an insulating support is installed for bearing an experimental sample; the infrared imager and the ultraviolet imager can acquire the image of the cable joint sample.
Furthermore, a sensor is arranged in the stretching device in the step S1.3, the force can be accurately set to 0.1N, and an automatic control center is arranged in a matched manner and used for controlling the starting and stopping of the machine, the stretching torque and the stretching frequency.
Further, the terahertz detection test device in the step S1.4 is a terahertz time-domain spectrometer, and the spectral range of the terahertz detection test device is 0-3.5 THz; the spectral resolution is 2 GHz; the dynamic range is larger than 60dB, the diameter of the terahertz light beam is 22mm, and the diameter of the terahertz focus is 1-2 mm.
Further, the specific process of step S2.1 is:
setting the stretching moment, stretching frequency and stretching duration until the experimental sample cracks, and calculating the stretching times; detecting the crack defect of the sample by using a terahertz time-domain spectrometer to obtain a terahertz time-domain spectrogram, and analyzing the internal change of the terahertz time-domain spectrogram;
and (3) in the experimental process, the tensile data is imported into a computer in real time for monitoring, and MATLAB real-time modeling analysis is carried out according to the experimental data to obtain a tensile data distribution diagram.
Further, the specific process of step S2.2 is:
carrying out experiments on samples at different times and different temperatures, monitoring in real time by using an infrared imager and an ultraviolet imager in the experiment process, and importing data into a computer; detecting the crack defect of the sample by using a terahertz time-domain spectrometer to obtain a terahertz time-domain spectrogram, and analyzing the internal change of the terahertz time-domain spectrogram;
the specific process of step S2.3 is:
performing a stretching experiment on the sample after the high-temperature test, setting the stretching moment, the stretching frequency and the stretching duration until the test sample cracks, and calculating the stretching times; detecting crack defects by using a terahertz system to obtain a terahertz time-domain spectrogram, and analyzing internal changes of the terahertz time-domain spectrogram;
and (3) importing all data into a computer in real time in the experimental process for monitoring, and carrying out MATLAB real-time modeling analysis according to the experimental data to obtain a tensile data distribution diagram of the data.
Further, the specific process of step S2.4 is:
when a sample is subjected to a high-temperature damp experiment, humidifying or dehumidifying of humidifying equipment in a test box is automatically controlled by temperature and humidity at the same time of temperature change so as to ensure that the sample is tested at different temperatures and humidity, and temperature and humidity data are automatically transmitted to a computer; in the experimental process, an infrared imager and an ultraviolet imager are used for real-time monitoring, and data are imported into a computer;
the specific process of step S2.5 is:
performing a stretching experiment on the sample subjected to high temperature and moisture, setting the stretching moment, stretching frequency and stretching duration until the experimental sample cracks, calculating the stretching times at the moment, detecting crack defects by using a terahertz system to obtain a terahertz time-domain spectrogram, and analyzing internal changes of the terahertz time-domain spectrogram;
and (3) importing the tensile data into a computer in real time for monitoring in the experimental process, and carrying out MATLAB real-time modeling analysis according to the experimental data to obtain a tensile data distribution diagram of the tensile data.
Further, the terahertz transmission and reflection coefficients obtained in step S3 are:
in the formula (1), ω is the angular frequency of the THz wave;
theta and beta are respectively an incident angle and a refraction angle;
a. s is an air medium and a sample medium respectively;
the complex dielectric constant of the sample was:
and acquiring related parameters through the terahertz time-domain spectrogram, and calculating the dielectric constant according to the formula.
Further, the process of establishing the fracture interference model in step S4 is as follows, and the mean value K of the stress intensity factor m And the variation Δ K are respectively expressed as:
K m ＝X(s m )·Y(a) (3)
ΔK＝[X(s max )-X(s min )]·Y(a)＝ΔX·Y(a) (4)
fatigue crack propagation threshold Δ K as known for stress intensity factor variation Δ K th Are respectively f (delta K) and g (delta K) th ) Then, it corresponds to any one of Δ K, Δ K th The probability of less than Δ K is:
f (Δ K) is a monotonic function of the random variable Δ K with a probability of occurrence of F (Δ K) d Δ K; thereby can be
To construct a differential df of the failure rate f:
df＝F(ΔK)f(ΔK)dΔK (6)
integrating the above equation to obtain the probability of the crack to continue to propagate, i.e. the failure rate f:
the framework crack non-propagation probability, i.e. the reliability, is:
substituting equation (5) into the above equation, then:
this is a one-dimensional fracture interference model.
The invention has the following beneficial effects:
(1) the invention utilizes the temperature and humidity automatic control test box to accurately simulate the high temperature and damp working condition in the working environment of the cable joint, and utilizes the high-voltage electric heating test box to replace the special equipment, thereby reducing the cost, having short temperature rise and temperature reduction time and quick humidification and dehumidification, and completely meeting the test requirements. The stretching device simulates the condition of sudden external force, and the simulated test environment and the actual working condition have high similarity by combining the stretching device and the actual working condition, so that the test result has higher reference value. The data of all the test equipment can be transmitted to a computer in real time for collection, collection and calculation, and the reliability is improved.
(2) The invention integrates the joint fracture accidents which are easy to happen in the actual working condition, analyzes the factors which influence the cable joint fracture by integrating the temperature, the humidity and the stretching degree, constructs the fracture interference model, realizes the health condition evaluation of the cable joint, judges the reasonable fracture degree, prevents the crack from continuing to expand, and ensures the safe work of the cable joint. The method can not only realize nondestructive online detection of the fracture degree of the composite cable joint, but also be used for infinite life damage tolerance design and fault analysis. The practicability is extremely strong, and the popularization prospect is good.
Drawings
FIG. 1 is a schematic diagram of a temperature and humidity automatic control test chamber in step S1.2 of the present invention;
FIG. 2 is a schematic view of the drawing apparatus used in step S1.3 of the present invention.
The reference numbers are as follows: firstly, automatically controlling a test box by temperature and humidity; stretching device; thirdly, an infrared imager; and fourthly, an ultraviolet imager.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings of the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.
Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention.
Example 1
Related test devices are correctly erected before the test, a fire extinguisher is prepared, safety protection work is well done, and property and personal safety are guaranteed.
As shown in fig. 1-2, the method for evaluating fatigue fracture life of a composite cable joint based on multi-source information fusion comprises the following steps:
s1, preparing a sample and test equipment;
s1.1, preparing a sample;
a complete XLPE cable splice was prepared as a test sample. The cable joint defect fracture defect is divided into three grades of defect-free, micro crack defect and serious crack defect, wherein: the depth of the micro crack is within 1cm, and the length of the crack is within 2 cm; the severe crack has a depth of 1cm or more and a length of 2cm or more.
S1.2, preparing an automatic temperature and humidity control test box;
the automatic temperature and humidity control test box is a test box capable of adjusting temperature and controlling humidity in the prior art, and the existing high-voltage electrothermal test box (I) of a test room is adopted in the embodiment, and is SF-401A, 2m long, 1.5m wide and 2m high. The left side of the case is provided with a control center which controls the start and stop of the machine and the setting of temperature and humidity, and the control center is digital display type. The experiment box is internally provided with a copper hook for conducting electricity and an insulating support for bearing an experiment sample. The equipment is transmitted and powered by the power cabinet and is safely grounded.
The temperature of the experimental box can be set to be 150 ℃ at most, and the working time is not limited.
The installation positions of the infrared imager and the ultraviolet imager matched with the infrared imager are shown in figure 1, and the infrared imager and the ultraviolet imager are ensured to be capable of acquiring images of cable joint samples.
S1.3, preparing tensile test equipment;
the existing stretching device II is adopted, the structural schematic diagram is shown in figure 2, the device is uT6820, the length is 0.7m, the width is 0.65m, the height is 2m, a sensor is arranged in the device, and the force can be accurately set to be 0.1N.
The right side of the device is provided with a control center for controlling the start and stop of the machine and setting the stretching moment and the stretching frequency.
S1.4, preparing terahertz detection test equipment;
the terahertz detection test equipment adopts the existing terahertz time-domain spectrometer with the model of CCT-1800, and mainly comprises the following components: femtosecond fiber laser; a THz lens transmitting antenna; a THz lens detection antenna; delay line (1ns time delay); a beam splitter and a beam splitter; moving the substrate clamping frame in the manual XY direction; electronic components (pulse generator + lock detection); notebook computer for spectrometer T3D software. The spectral range is 0-3.5THz and is determined by the laser wavelength; the spectral resolution is 2 GHz; the dynamic range is larger than 60dB, the diameter of the terahertz light beam is 22mm, and the diameter of the terahertz focus is 1-2 mm.
S2, sample testing and data acquisition;
the image acquisition and data processing system applies Word files, Excel files, Visio files, BMP files and MATLAB simulation software in the prior art.
S2.1, collecting tensile test data and carrying out terahertz detection on the tested sample to obtain a time domain spectrogram;
and setting the stretching moment, the stretching frequency and the stretching time till the experimental sample cracks, and calculating the stretching times at the moment. And detecting the crack defect of the sample by using a terahertz time-domain spectrometer to obtain a terahertz time-domain spectrogram and analyzing the internal change of the terahertz time-domain spectrogram.
And (3) in the experimental process, the tensile data is imported into a computer in real time for monitoring, and MATLAB real-time modeling analysis is carried out according to the experimental data to obtain a tensile data distribution diagram.
S2.2, collecting high-temperature test data and carrying out terahertz detection on the tested sample to obtain a time domain spectrogram;
the method comprises the steps of carrying out experiments on samples at different times and different temperatures, monitoring in real time by using an infrared imager and an ultraviolet imager in the experiment process, and importing data into a computer.
And detecting the crack defect of the sample by using a terahertz time-domain spectrometer to obtain a terahertz time-domain spectrogram and analyzing the internal change of the terahertz time-domain spectrogram.
S2.3, stretching the sample subjected to the high-temperature test in the S2.2 again, and collecting test data; carrying out terahertz detection on the sample after the tensile test to obtain a time domain spectrogram;
the samples after the high temperature test were then subjected to a tensile test. And setting the stretching moment, the stretching frequency and the stretching time till the experimental sample cracks, and calculating the stretching times at the moment. And detecting the crack defect by using a terahertz system to obtain a terahertz time-domain spectrogram and analyzing the internal change of the terahertz time-domain spectrogram.
And (3) importing all data into a computer in real time in the experimental process for monitoring, and carrying out MATLAB real-time modeling analysis according to the experimental data to obtain a tensile data distribution diagram of the data.
S2.4, collecting high-temperature and damp test data and carrying out terahertz detection on the tested sample to obtain a time domain spectrogram;
when a sample is subjected to a high-temperature damp experiment, humidification or dehumidification is performed while the temperature of humidification equipment in the temperature and humidity automatic control test box is changed. So as to ensure that the sample is tested under different humiture, and the humiture data is automatically transmitted to a computer. And in the experimental process, real-time monitoring is carried out by using an infrared imager and an ultraviolet imager, and data are imported into a computer.
S2.5, stretching the sample subjected to the high-temperature and damp test in the S2.4 again, and collecting test data; carrying out terahertz detection on the sample after the tensile test to obtain a time domain spectrogram;
the samples after the high temperature and moisture exposure were then subjected to tensile testing. And setting the stretching moment, stretching frequency and stretching duration until the test sample cracks, and calculating the stretching times at the moment. And detecting the crack defect by using a terahertz system to obtain a terahertz time-domain spectrogram and analyzing internal changes of the terahertz time-domain spectrogram.
And (3) importing the tensile data into a computer in real time for monitoring in the experimental process, and carrying out MATLAB real-time modeling analysis according to the experimental data to obtain a tensile data distribution diagram of the tensile data.
S3, processing data;
performing Word arrangement and Visio graphic analysis on the data acquired in S2.1-S2.5, performing MATLAB data conversion according to the acquired data, and performing data comparison reference on the stretched experimental sample and the unstretched experimental sample;
obtaining the terahertz transmission and reflection coefficients as follows:
in the formula (1), ω is the angular frequency of the THz wave;
theta and beta are respectively an incident angle and a refraction angle;
a. s is air medium and sample medium, respectively.
The complex dielectric constant of the sample was:
relevant parameters are obtained through the terahertz time-domain spectrogram, and the dielectric constant can be calculated according to the formula.
S4, establishing a fracture interference model;
when a component containing a crack or an initial defect bears steady-state random cyclic stress, in order to ensure the safe operation of the component, the stress intensity factor variation range is controlled below a fatigue crack propagation threshold value so as to prevent the crack from continuing to propagate.
Therefore, the stress intensity factor variation and the fatigue crack propagation threshold value are obtained according to the data in S3, and a fracture interference model is established.
Mean value of stress intensity factor K m And the variation Δ K are respectively expressed as
K m ＝X(s m )·Y(a) (3)
ΔK＝[X(s max )-X(s min )]·Y(a)＝ΔX·Y(a) (4)
Fatigue crack propagation threshold Δ K as known for stress intensity factor variation Δ K th Are respectively f (delta K) and g (delta K) th ) Then, it corresponds to any one of Δ K, Δ K th The probability of less than Δ K is:
f (Δ K) is a monotonic function of the random variable Δ K, with a probability of occurrence of F (Δ K) d Δ K. Thereby can be
To construct a differential df of the failure rate f:
df＝F(ΔK)f(ΔK)dΔK (6)
integrating the above equation to obtain the probability of the crack to continue to propagate, i.e. the failure rate f:
the framework crack non-propagation probability, i.e. the reliability, is:
substituting equation (5) into the above equation, then:
this is a one-dimensional fracture interference model.
S5, applying the result;
and performing terahertz detection on the cable joint in actual operation to obtain the defect condition of the XLPE cable joint sample, substituting the defect condition into the fracture interference model established in S4, estimating a reasonable fracture degree, preventing the crack from continuing to expand and ensuring the safe operation of the crack.
In conclusion, the method can not only be used for nondestructive online detection of the fracture degree of the composite cable joint, but also be used for infinite life damage tolerance design and fault analysis. The practicability is extremely strong, and the popularization prospect is good.
Claims (9)
1. The composite cable joint fatigue fracture life evaluation method based on multi-source information fusion comprises the following steps: s1, preparing a sample and test equipment;
s1.1, preparing a sample;
preparing a complete XLPE cable joint as a test sample, and classifying the defect and fracture defects of the cable joint into three grades of defect-free, micro-crack defect and severe crack defect;
s1.2, preparing an automatic temperature and humidity control test box;
s1.3, preparing tensile test equipment;
s1.4, preparing terahertz detection test equipment;
s2, sample testing and data acquisition;
the image acquisition and data processing system applies Word files, Excel files, Visio files, BMP files and MATLAB simulation software in the prior art;
s2.1, collecting tensile test data and carrying out terahertz detection on the tested sample to obtain a time domain spectrogram;
s2.2, collecting high-temperature test data and carrying out terahertz detection on the tested sample to obtain a time domain spectrogram;
s2.3, stretching the sample subjected to the high-temperature test in the S2.2 again, and collecting test data; carrying out terahertz detection on the sample after the tensile test to obtain a time domain spectrogram;
s2.4, collecting high-temperature and damp test data and carrying out terahertz detection on the tested sample to obtain a time domain spectrogram;
s2.5, stretching the sample subjected to the high-temperature and damp test in S2.4 again, and collecting test data; carrying out terahertz detection on the sample after the tensile test to obtain a time domain spectrogram;
s3, processing data;
carrying out Word arrangement and Visio mapping analysis on the data acquired in S2.1-S2.5, carrying out MATLAB data conversion according to the acquired data, and carrying out data comparison reference on the stretched experimental sample and the unstretched experimental sample;
obtaining terahertz transmission and reflection coefficients through a terahertz time-domain spectrogram, and further calculating the complex dielectric constant of the sample;
s4, establishing a fracture interference model;
when a component containing a crack or an initial defect bears steady-state random cyclic stress, in order to ensure the safe operation of the component, the stress intensity factor variation range is controlled below a fatigue crack propagation threshold value so as to prevent the crack from continuing to propagate;
therefore, a stress intensity factor variation range and a fatigue crack propagation threshold value are obtained by relying on data in S3, and a fracture interference model is established;
s5, applying results;
and performing terahertz detection on the cable joint in actual operation to obtain the defect condition of an XLPE cable joint sample, substituting the defect condition into the fracture interference model established in S4, estimating a reasonable fracture degree, preventing the crack from continuing to expand and ensuring the safe operation of the crack.
2. The composite cable joint fatigue fracture life assessment method based on multi-source information fusion of claim 1, wherein: the temperature and humidity automatic control test box in the step S1.2 is a high-voltage electrothermal test box I with adjustable temperature and controllable humidity, a copper hook is installed inside the test box for conducting electricity, and an insulating support is installed for bearing an experimental sample; the infrared imager and the ultraviolet imager can collect the image of the cable joint sample.
3. The composite cable joint fatigue fracture life assessment method based on multi-source information fusion of claim 1, wherein: and a sensor is arranged in the stretching device in the step S1.3, the force can be accurately set to 0.1N, and an automatic control center is arranged in a matched manner and used for controlling the starting and stopping of the machine, the stretching torque and the stretching frequency.
4. The composite cable joint fatigue fracture life assessment method based on multi-source information fusion of claim 1, wherein: the terahertz detection test device in the step S1.4 is a terahertz time-domain spectrometer, and the spectral range of the terahertz time-domain spectrometer is 0-3.5 THz; the spectral resolution is 2 GHz; the dynamic range is larger than 60dB, the diameter of the terahertz light beam is 22mm, and the diameter of the terahertz focus is 1-2 mm.
5. The composite cable joint fatigue fracture life assessment method based on multi-source information fusion of claim 1, wherein: the specific process of step S2.1 is:
setting the stretching moment, stretching frequency and stretching duration until the experimental sample cracks, and calculating the stretching times; detecting the crack defect of the sample by using a terahertz time-domain spectrometer to obtain a terahertz time-domain spectrogram, and analyzing the internal change of the terahertz time-domain spectrogram;
and (3) importing the tensile data into a computer in real time for monitoring in the experimental process, and carrying out MATLAB real-time modeling analysis according to the experimental data to obtain a tensile data distribution diagram of the tensile data.
6. The composite cable joint fatigue fracture life assessment method based on multi-source information fusion of claim 1, wherein:
the specific process of step S2.2 is:
carrying out experiments on samples at different times and different temperatures, monitoring in real time by using an infrared imager and an ultraviolet imager in the experiment process, and importing data into a computer; detecting the crack defect of the sample by using a terahertz time-domain spectrometer to obtain a terahertz time-domain spectrogram, and analyzing the internal change of the terahertz time-domain spectrogram;
the specific process of step S2.3 is:
performing a stretching experiment on the sample after the high-temperature test, setting the stretching moment, the stretching frequency and the stretching duration until the experimental sample cracks, and calculating the stretching times; detecting crack defects by using a terahertz system to obtain a terahertz time-domain spectrogram, and analyzing internal changes of the terahertz time-domain spectrogram;
and (3) importing all data into a computer in real time in the experimental process for monitoring, and carrying out MATLAB real-time modeling analysis according to the experimental data to obtain a tensile data distribution map of the data.
7. The composite cable joint fatigue fracture life assessment method based on multi-source information fusion of claim 1, wherein:
the specific process of step S2.4 is:
when a high-temperature damp experiment is carried out on a sample, humidifying or dehumidifying is carried out by using humidifying equipment in a temperature and humidity automatic control test box while the temperature changes so as to ensure that the sample is tested under different temperatures and humidities, and temperature and humidity data are automatically transmitted to a computer; in the experimental process, an infrared imager and an ultraviolet imager are used for real-time monitoring, and data are imported into a computer;
the specific process of step S2.5 is:
performing a stretching experiment on the sample subjected to high temperature and moisture, setting the stretching moment, stretching frequency and stretching duration until the experimental sample cracks, calculating the stretching times at the moment, detecting crack defects by using a terahertz system to obtain a terahertz time-domain spectrogram, and analyzing internal changes of the terahertz time-domain spectrogram;
and (3) in the experimental process, the tensile data is imported into a computer in real time for monitoring, and MATLAB real-time modeling analysis is carried out according to the experimental data to obtain a tensile data distribution diagram.
8. The composite cable joint fatigue fracture life assessment method based on multi-source information fusion of claim 1, wherein: the terahertz transmission and reflection coefficients obtained in step S3 are:
in the formula (1), ω is the angular frequency of the THz wave;
theta and beta are respectively an incident angle and a refraction angle;
a. s is an air medium and a sample medium respectively;
the complex dielectric constant of the sample was:
and acquiring related parameters through the terahertz time-domain spectrogram, and calculating the dielectric constant according to the formula.
9. The composite cable joint fatigue fracture life assessment method based on multi-source information fusion of claim 1, wherein: the process of establishing the fracture interference model in step S4 is as follows, the mean value K of the stress intensity factor m And the variation Δ K are respectively expressed as:
K m ＝X(s m )·Y(a) (3)
ΔK＝[X(s max )-X(s min )]·Y(a)＝ΔX·Y(a) (4)
fatigue crack propagation threshold value delta K as known for stress intensity factor variation delta K th Are respectively f (delta K) and g (delta K) th ) Then, it corresponds to any one of Δ K, Δ K th The probability of less than Δ K is:
f (Δ K) is a monotonic function of the random variable Δ K with a probability of occurrence of F (Δ K) d Δ K; from this, the differential df of the failure rate f can be constructed:
df＝F(ΔK)f(ΔK)dΔK (6)
integrating the above equation, the probability of crack propagation, i.e. the failure rate f, is obtained:
the framework crack non-propagation probability, i.e. the reliability, is:
substituting equation (5) into the above equation, then:
this is a one-dimensional fracture interference model.
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116911068A (en) * | 2023-09-06 | 2023-10-20 | 成都汉度科技有限公司 | Method and system for predicting effective life of cable joint |
| CN118376897A (en) * | 2024-06-26 | 2024-07-23 | 浙江大有实业有限公司电缆工程分公司 | Cable GIS terminal performance test system and method |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116911068A (en) * | 2023-09-06 | 2023-10-20 | 成都汉度科技有限公司 | Method and system for predicting effective life of cable joint |
| CN116911068B (en) * | 2023-09-06 | 2023-11-28 | 成都汉度科技有限公司 | Method and system for predicting effective life of cable joint |
| CN118376897A (en) * | 2024-06-26 | 2024-07-23 | 浙江大有实业有限公司电缆工程分公司 | Cable GIS terminal performance test system and method |
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