Device and method for testing bearing capacity of polyurethane composite material electric pole

Abstract

The invention relates to the technical field of bearing capacity testing, in particular to a device and method for testing the bearing capacity of a polyurethane composite material electric pole. According to the method, the bearing state is represented according to the deformation representation at the moment, and after a creep threshold value is adjusted from the temperature change and the bearing state reduction change, the offset of the bearing state change is analyzed to correct the static load; the creep resistance index is obtained by combining the static load change and the bearing state; the dynamic load amplitude is corrected according to the correlation condition of the temperature and the bearing state in the time sequence and the temperature change, the dynamic load frequency is adjusted through the change rate of the bearing state, and the anti-fatigue index is obtained in combination with the bearing state; and a bearing test result is obtained by integrating deformation and a bearing state according to the trend conditions of creep resistance and fatigue resistance. According to the invention, the load parameters are dynamically adjusted by combining the dynamic fatigue of temperature change and the creep test, the load capacity of the electric pole in different environments is more comprehensively tested, and a more accurate electric pole bearing capacity test result is obtained.

Description

Technical Field

[0001] The present invention relates to the technical field of bearing capacity testing, and particularly relates to a bearing capacity testing device and method for a polyurethane composite material electric pole. Background Art

[0002] Polyurethane (PU), whose full name is polycarbamate, is a polymer material formed by the polycondensation reaction of polyols and polyisocyanates and has excellent mechanical properties and extremely strong plasticity. The polyurethane composite material electric pole is a new type of electric pole material made of polyurethane as the carrier and glass fiber as the reinforcing body by a specific process. Since the electric poles made of this material have the advantages of convenient installation, low maintenance cost, high safety performance, and environmental protection and energy saving, they are widely used in fields such as transmission lines and distribution systems.

[0003] The working environment of electric poles is usually outdoors. In some special cases, such as extreme weather (strong wind, heavy rain, heavy snow, ice disasters, etc.) or geological disasters (such as earthquakes, etc.), the loads borne by electric poles will far exceed the loads during normal operation. Bearing capacity testing can help evaluate the bearing capacity of electric poles under these extreme working conditions, verify whether they are safe enough to cope with potential risks, and ensure the continuity and reliability of power supply in harsh environments.

[0004] The polyurethane composite material has the characteristics of high toughness and low stiffness, and is prone to plastic deformation or crack propagation. In addition, this material is highly sensitive to temperature, with characteristics of low-temperature embrittlement and high-temperature softening. However, when the existing devices test the bearing capacity of electric poles, they usually do not consider the influence of extreme weather, mainly conduct tests in a stable environment, and in order to improve the test efficiency during the test process, mainly choose to conduct static or high-frequency dynamic tests on electric poles, such as fatigue tests above 50 Hz for electric poles, without considering the temperature change and load capacity influence in complex environments, so the long-term service performance cannot be effectively evaluated, resulting in inaccurate test results for the bearing capacity of electric poles. Summary of the Invention

[0005] In order to solve the technical problems in the prior art that the temperature change and load capacity influence in complex environments are not considered, the long-term service performance cannot be effectively evaluated, and the test results for the bearing capacity of electric poles are inaccurate, the purpose of the present invention is to provide a bearing capacity testing device and method for a polyurethane composite material electric pole, and the specific technical solutions adopted are as follows: The present invention provides a bearing capacity testing method for a polyurethane composite material electric pole, and the method includes: In the variable-temperature bearing capacity test, obtain the temperature, various deformation parameters, static load, dynamic load amplitude, and dynamic load frequency of the electric pole at each moment; obtain the bearing state value at each moment according to the various deformation parameters at each moment; Adjust the creep rate threshold according to the temperature change at the moment and the degree of reduction of the bearing state value; analyze the deviation of the change rate of the bearing state value based on the currently adjusted creep rate threshold, and correct the static load in combination with the bearing state value to obtain the static load at the next moment; obtain the anti-creep index at the moment according to the static load change and the bearing state value at each moment; Based on the correlation relationship between the bearing state value and the temperature in time series, and the correction of the dynamic load amplitude by the current temperature change, obtain the dynamic load amplitude at the next moment; adjust the dynamic load frequency by the fluctuation of the change rate of the current bearing state value to obtain the dynamic load frequency at the next moment; obtain the anti-fatigue index at the moment according to the bearing state value at each moment, and the distribution of the previous dynamic load amplitude and the dynamic load frequency; Determine the stop moment according to the size of the bearing state index; obtain the bearing capacity test result by the trend change of the anti-creep index and the anti-fatigue index before the stop moment, and combine the bearing state value distribution and the load deviation distribution under deformation;

[0006] Further, the method for obtaining the bearing state includes: The deformation parameters include the crack area, the strain values at all positions on the pole, and the displacement of the support plate; For any moment, perform negative correlation mapping and normalization on the variance of the strain values at all positions at this moment to obtain the strain bearing degree; perform negative correlation mapping and normalization on the displacement of the support plate at this moment to obtain the displacement bearing degree; perform weighted summation on the strain bearing degree and the displacement bearing degree at this moment to obtain the deformation bearing capacity at this moment; Perform normalization on the product of the value obtained by performing negative correlation mapping on the crack area at this moment and the deformation bearing capacity to obtain the bearing state value at this moment.

[0007] Further, the adjusting the creep rate threshold according to the temperature change at the moment and the degree of reduction of the bearing state value includes: For any moment, take the difference between the temperature at this moment and the previous average temperature as the temperature offset at this moment; Within the preset previous range at this moment, calculate the average rate of reduction of the bearing state index and perform negative correlation mapping to obtain the reduction adjustment degree; Combine the temperature offset and the reduction adjustment degree to obtain the threshold adjustment coefficient at this moment; multiply the preset rate threshold by the threshold adjustment coefficient, and calculate the sum of the product and the preset rate threshold as the adjusted creep rate threshold at this moment.

[0008] Further, the method for obtaining the static load at the next moment includes: Calculate the change rate of the bearing state value between each moment and the previous moment as the creep rate at each moment; When the creep rate is greater than or equal to the adjusted creep rate threshold, the ratio of the difference between the creep rate and the adjusted creep rate threshold to the adjusted creep rate threshold is used as the adjustment ratio; the product of the value obtained by negatively correlating the load-bearing state value at the corresponding moment and the adjustment ratio is used as the load adjustment coefficient at that moment; after multiplying the static load at that moment by the load adjustment coefficient, the difference between the static load at that moment and the product is calculated as the static load at the next moment.

[0009] Further, the method for obtaining the anti-creep index includes: For each moment, the difference in static load between each moment and the next moment is used as the adjustment amplitude for each moment; The value obtained by negatively correlating the load-bearing state at each moment with the adjustment amplitude is multiplied to obtain the anti-creep index at each moment.

[0010] Further, the method for obtaining the dynamic load amplitude at the next moment includes: For any moment, in the time series before that moment, a two-dimensional coordinate system is constructed based on the temperature and load-bearing state value at the moment; the horizontal axis in the two-dimensional coordinate system is the temperature, and the vertical axis is the load-bearing state value; each moment is mapped into the two-dimensional coordinate system and linearly fitted, and the slope of the fitted line is used as the temperature sensitivity coefficient; After calculating the temperature difference between that moment and the previous moment, the ratio of the temperature difference to the temperature at that moment is used as the temperature change degree; the product of the temperature change degree and the temperature sensitivity coefficient is used as the temperature adjustment coefficient; after multiplying the temperature adjustment coefficient by the dynamic load amplitude at that moment, the difference between the dynamic load amplitude at that moment and the product is calculated as the dynamic load amplitude at the next moment.

[0011] Further, the method for obtaining the dynamic load frequency at the next moment includes: The ratio of the difference between the creep rate at each moment and the historical average creep rate to the historical average creep rate is used as the frequency adjustment coefficient for each moment; After multiplying the dynamic load frequency at each moment by the frequency adjustment coefficient, the difference between the dynamic load frequency and the product is calculated as the dynamic load frequency at the next moment.

[0012] Further, the method for obtaining the anti-fatigue index includes: For any moment, combining all the dynamic load amplitudes, dynamic load frequencies, and test durations before that moment to obtain the cumulative index at that moment; the product of the cumulative index and the load-bearing state value at that moment is normalized to obtain the anti-fatigue index at that moment.

[0013] Further, the method for obtaining the bearing capacity test result includes: Before the stop moment in time sequence, perform a linear fitting on the numerical distribution of the anti-creep index in time sequence, perform a negative correlation mapping on the fitting slope, and obtain the creep life evaluation value; perform a linear fitting on the numerical distribution of the anti-fatigue index in time sequence, perform a negative correlation mapping on the fitting slope, and obtain the fatigue life evaluation value; Combine the creep life evaluation value and the fatigue life evaluation value to obtain the life evaluation index; Perform a negative correlation mapping on the difference between the load at the deformation start moment and the maximum load between the deformation start and stop moments to obtain the toughness evaluation index; Combine all the bearing state values, life evaluation index, and toughness evaluation index in time sequence to obtain the bearing capacity index as the bearing capacity test result.

[0014] The present invention also provides a bearing capacity test device for a polyurethane composite material electric pole, including a temperature control module and a variable temperature test module. The temperature control module is used to control temperature changes; the variable temperature test module includes a collection unit, an analysis and control unit, and a test evaluation unit; The signal output end of the collection unit is connected to the signal input end of the analysis and control unit, the signal output end of the analysis and control unit is connected to the signal input end of the test evaluation unit. The analysis and control unit is used for data analysis and regulation of subsequent loads; the test evaluation unit is used to evaluate the test result; The collection unit obtains temperature, various deformation parameters, static load, dynamic load amplitude, and dynamic load frequency at each moment through sensors, and transmits the acquired data to the analysis and control unit; The analysis and control unit obtains the bearing state value at each moment according to various deformation parameters at each moment; adjusts the creep rate threshold according to the temperature change and the reduction degree of the bearing state value at the moment; analyzes the deviation of the change rate of the bearing state value based on the currently adjusted creep rate threshold, and corrects the static load in combination with the bearing state value to obtain the static load at the next moment; obtains the anti-creep index at the moment according to the change of the static load and the bearing state value at each moment; Based on the correlation relationship between the bearing state value and temperature in time sequence, and correct the dynamic load amplitude according to the current temperature change to obtain the dynamic load amplitude at the next moment; adjust the dynamic load frequency by the fluctuation of the change rate of the current bearing state value to obtain the dynamic load frequency at the next moment; obtain the anti-fatigue index at the moment according to the bearing state value at each moment, and the previous dynamic load amplitude and dynamic load frequency distribution; Determine the stop moment according to the size of the bearing state index; transmit the analysis data before the stop moment to the test evaluation unit; The test evaluation unit obtains the bearing capacity test result through the trend changes of the anti-creep index and anti-fatigue index in the previous sequence before the stop moment, in combination with the bearing state value distribution and the load deviation distribution under deformation.

[0015] The present invention has the following beneficial effects: Through the physical characteristic deformation in the bearing capacity test of the electric pole under temperature change, the static load and dynamic load tests are carried out simultaneously, which is convenient to analyze the long-term service life of the electric pole from the perspectives of creep resistance and fatigue resistance, so as to more comprehensively test the load capacity of the electric pole under complex conditions. First, the bearing state is characterized by the deformation performance at a certain moment. After adjusting the creep rate threshold from the temperature change and the reduction change of the real-time bearing state, the static load is adjusted through the offset of the change rate of the bearing state at a certain moment. Considering the change of the creep rate caused by the influence of temperature on the internal activity of the material, the overload acceleration damage is avoided, which affects the bearing evaluation. Combining the static load change and the bearing state, the creep resistance index is obtained. Further, from the correlation between temperature and bearing state in time series, and the correction of the dynamic load amplitude by the temperature change at a certain moment, considering the decrease of the material modulus at high temperature, the dynamic load amplitude needs to be adjusted to adapt to the actual working conditions. And through the change rate of the bearing state value, the dynamic load frequency is adjusted, considering the weakened fatigue situation in creep analysis, so as to adjust the rhythm of the fatigue resistance test. Finally, by comprehensively considering the accumulated state in time series and the bearing state at a certain moment, the fatigue resistance index is obtained. After the limit of the real-time bearing state stops, through the trend of creep resistance and fatigue resistance in the test, combining the bearing state and the load change that generates deformation, the bearing test result is comprehensively obtained. Considering the creep life, fatigue life, toughness of the deformed load, and the three factors of the bearing state, a better bearing capacity test result is comprehensively obtained. By combining the dynamic fatigue and creep tests with temperature change, the load parameters are dynamically adjusted according to the real-time temperature and the real-time state of the electric pole during the test, so as to more comprehensively test the load capacity of the electric pole in different environments and obtain more accurate bearing capacity test results of the electric pole. Description of the Drawings

[0016] In order to more clearly illustrate the technical solutions and advantages in the embodiments of the present invention or the prior art, the drawings required for use in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0017] Figure 1 It is a flowchart of a method for testing the bearing capacity of a polyurethane composite electric pole provided by an embodiment of the present invention; Figure 2 It is a schematic structural diagram of a device for testing the bearing capacity of a polyurethane composite electric pole provided by an embodiment of the present invention; Figure 3 It is a schematic structural diagram of a detection table provided by an embodiment of the present invention; Figure 4Schematic diagram of a cover plate structure provided by an embodiment of the present invention; Figure 5 Schematic diagram of a protective frame structure provided by an embodiment of the present invention; Figure 6 Schematic diagram of the installation position structure of a distributed fiber optic grating sensor provided by an embodiment of the present invention; Figure 7 Schematic diagram of the application of static load and dynamic load provided by an embodiment of the present invention; Figure 8 Schematic diagram of a strain value distribution curve provided by an embodiment of the present invention; Mark the following reference numerals on the drawings in combination with the attached drawings: 1, test bench; 10, sliding groove; 11, guide rod; 12, first hydraulic cylinder; 2, bottom placement table; 20, internal insertion tube; 3, slider; 30, corrosion-resistant steel pipe; 31, sleeve plate; 32, sector support plate; 33, displacement sensor; 4, protective frame; 40, protective net; 41, vision sensor; 42, acoustic emission sensor; 50, magnetic induction patch; 5, indicator light; 60, hinge; 6, cover plate; 61, compressive strength detection box; 62, second hydraulic cylinder; 70, control rod; 7, pressing plate; 71, connecting rod; 72, pressure sensor probe plate; 73, iron indicator tube; 74, distributed fiber optic grating sensor; 8, electric servo actuator; 9, temperature control module; 33, displacement sensor; 41, vision sensor; 42, acoustic emission sensor; 74, distributed fiber optic grating sensor. Detailed implementation manners

[0018] In order to further elaborate on the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the following combines the attached drawings and preferred embodiments to detail the specific implementation manners, structures, features and effects of a bearing capacity testing device and testing method for a polyurethane composite material electric pole proposed according to the present invention. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. In addition, the specific features, structures or characteristics in one or more embodiments can be combined in any suitable form.

[0019] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs.

[0020] The following specifically describes the specific scheme of a bearing capacity testing device and testing method for a polyurethane composite material electric pole provided by the present invention in combination with the attached drawings. Figures 2 to 6, in a bearing capacity test device for a polyurethane composite pole, the temperature control module 9 is installed inside the test bench 1, including a PTC heating sheet and a liquid cooling circulation pipeline, and is used to control temperature changes; the electric servo actuator 8 is installed on the second hydraulic cylinder 62 and is used to control load output; the distributed fiber optic grating sensor 74 is installed at the bottom of the pressure plate 7 and is used to obtain the surface strain distribution of the polyurethane pole in real time; the displacement sensor 33 is installed inside the sector support plate 32 and is used to obtain the displacement of the support plate in real time and quantify the expansion deformation amplitude inside the pole; the vision sensor 41 is installed on the protective frame 4 and is used to collect the surface image information of the pole in real time; the acoustic emission sensor 42 is installed on the protective frame 4 and is used to collect the signals of material delamination or fiber fracture of the pole in real time.

[0021] Among them, the temperature control module 9 simulates the temperature changes in daily environments and extreme weather conditions through artificial intelligence algorithms. For example, when simulating the day-night changes in summer, the temperature is controlled to rise from 15°C to 40°C and then gradually decrease from 40°C to 20°C, with a cycle of 1 hour. The average temperature change ranges are obtained for different seasons. For example, the average temperature in spring is between 5°C and 20°C, etc. It can be understood that the specific temperature control situation can be adjusted by the implementer according to the specific implementation scenario and is not limited here.

[0022] Place the polyurethane composite pole into the device, and by adjusting components such as the first hydraulic cylinder 12, the second hydraulic cylinder 62, the sector support plate 32, and the pressure plate 7, the pole is fixed in the device for a variable-temperature bearing capacity test. Before the test, clean the surface of the polyurethane composite pole to ensure the flatness of the sensor fitting area, and calibrate each sensor through existing instruments or existing methods to ensure that it can collect data normally. At the same time, ensure that the load output errors of the first hydraulic cylinder 12, the second hydraulic cylinder 62, and the electric servo actuator are less than 2%. During the test, combine creep testing and fatigue testing. Creep testing is that the electric servo actuator applies a static load to the pole, and at the same time, fatigue testing is carried out, that is, a dynamic load is superimposed on the basis of the static load, so as to more realistically simulate the actual scenario. Start the temperature control module and collect real-time data through the installed sensors. Please refer to Figure 7 , which shows a schematic diagram of the application of static load and dynamic load provided by an embodiment of the present invention, the initial additional conditions of the static load and the dynamic load, and the implementer can adjust according to the specific implementation scenario and is not limited here.

[0023] A bearing capacity test device for a polyurethane composite material electric pole further includes a variable temperature test module. The variable temperature test module includes a collection unit, an analysis and control unit, and a test and evaluation unit. The signal output end of the collection unit is connected to the signal input end of the analysis and control unit. After transmitting the acquired data to the analysis and control unit, the analysis and control unit performs data analysis and regulates the subsequent load of the test. The signal output end of the analysis and control unit is connected to the signal input end of the test and evaluation unit. The test and evaluation unit evaluates the test data. The variable temperature test module can be a conventional processor chip such as a single-chip microcomputer, for example: FPGA, CPU, MCU, etc.

[0024] For the analysis and evaluation of the bearing capacity test, please refer to Figure 1 , which shows a flowchart of a bearing capacity test method for a polyurethane composite material electric pole provided by an embodiment of the present invention. The method includes the following steps: S1: In the variable temperature bearing capacity test, obtain the temperature, various deformation parameters, static load, dynamic load amplitude, and dynamic load frequency of the electric pole at each moment; obtain the bearing state value at each moment according to the various deformation parameters at each moment.

[0025] As the bearing capacity test of the polyurethane composite electric pole progresses, cracks will gradually appear on the surface of the electric pole, and due to the uneven stress distribution inside the electric pole, offsets and expansions will gradually occur. Combining the real-time acquisition results of the sensors, determine the real-time bearing state index of the polyurethane composite material electric pole. The better the state of the electric pole, the larger the bearing state index.

[0026] Therefore, through the deformation parameter situation of the electric pole, the real-time monitored bearing state is first obtained. In the embodiment of the present invention, the deformation parameters include the crack area, the strain values at all positions on the electric pole, and the displacement of the support plate. The crack area is obtained by collecting the surface image through a visual sensor and using a semantic segmentation algorithm to segment the cracks to obtain the crack area. The total number of pixel points in the crack area is used as the crack area. The larger the crack area, the worse the current bearing state of the electric pole may be.

[0027] The distribution of the strain values at all positions on the electric pole can reflect the bearing situation of the electric pole. When the strain distribution on the surface of the electric pole is more uniform, it indicates that the electric pole is still in the elastic stage and the bearing state is better. On the contrary, it indicates that the electric pole has begun to become unbalanced, the bearing capacity has begun to decrease, and the more uneven the distribution, the weaker the bearing capacity. Please refer to Figure 8 , which shows a schematic diagram of a strain value distribution curve provided by an embodiment of the present invention. Therefore, for any moment, perform a negative correlation mapping and normalization processing on the variance of the strain values at all positions at that moment to obtain the strain bearing degree. The smaller the variance, the stronger the bearing state is reflected.

[0028] Meanwhile, the displacement of the support plate characterizes the displacement magnitude at the sector-shaped support plate. When the displacement of the support plate occurs, it indicates that deformation begins to occur inside the pole, and the internal deformation becomes more obvious as the displacement increases. Therefore, the displacement of the support plate at this moment is subjected to negative correlation mapping and normalization processing to obtain the displacement bearing capacity. When the displacement of the support plate does not occur, the bearing state is better.

[0029] Since the influence of the support plate displacement and strain distribution on the bearing state is different. For example, when there is no displacement at the sector-shaped support plate and the surface strain of the pole is uneven, the bearing capacity is weak. When there is obvious displacement at the sector-shaped support plate and the surface strain of the pole is uniform, the bearing capacity is strong. The degree of strain distribution uniformity is more important than the degree of support plate displacement.

[0030] Therefore, the strain bearing capacity and displacement bearing capacity at this moment are weighted and summed to obtain the deformation bearing capacity at this moment. In the embodiment of the present invention, the weight of the strain bearing capacity is set to 0.7, and the weight of the displacement bearing capacity is set to 0.3. The specific numerical values can be adjusted by the implementer and are not limited here.

[0031] Finally, in combination with the generation situation of the crack area, the product of the value after negative correlation mapping of the crack area at this moment and the deformation bearing capacity is normalized to obtain the bearing state value at this moment. The better the state of the pole, the larger the corresponding bearing state value.

[0032] It should be noted that both negative correlation mapping and normalization processing are well-known technical means to those skilled in the art. Negative correlation means that the dependent variable increases as the independent variable decreases. Negative correlation mapping can adopt forms such as inverse proportion or negative exponential power, etc. The choice of normalization can be linear normalization or standard normalization, etc. The specific negative correlation mapping and normalization methods are not limited and elaborated here.

[0033] S2: According to the temperature change and the reduction degree of the bearing state value at the moment, adjust the creep rate threshold; analyze the deviation of the change rate of the bearing state value based on the currently adjusted creep rate threshold, and combine the bearing state value to correct the static load to obtain the static load at the next moment; obtain the anti-creep index at the moment according to the change of the static load and the bearing state value at each moment.

[0034] For the creep test of the polyurethane composite pole, it mainly involves applying a constant static load to the pole and observing the creep situation of the pole under the static load. Since the environmental temperature simulates the real day-night and seasonal changes, and when in a high-temperature environment, the activity inside the pole material increases, which leads to an accelerated creep rate of the pole. When the creep rate of the pole exceeds a certain threshold at different temperatures, it indicates that the pole may be about to break, underestimating the true bearing capacity. Therefore, it is necessary to adjust the static load to avoid misjudging normal creep as failure at high temperatures.

[0035] When the temperature is higher, it indicates that the material has higher activity and higher softening degree, and the threshold needs to be increased to tolerate normal deformation. On the contrary, when the temperature is lower, it indicates that the material has a higher degree of embrittlement, and the threshold needs to be increased to sensitively capture the risk of brittle fracture. At the same time, through the rate of change of the load-bearing state, when the degree of decrease is greater, it reflects that the material is damaged faster, and the adjustment range needs to be controlled when adjusting the threshold. When the degree of decrease is smaller, it reflects that the material is damaged slower, the material is stronger and tougher, and a greater sensitive adjustment is allowed.

[0036] Therefore, preferably, in the embodiment of the present invention, according to the temperature change at a moment and the degree of decrease of the load-bearing state value, the creep rate threshold is adjusted, including: For any moment, the difference between the temperature at this moment and the previous average temperature is used as the temperature deviation degree at this moment, reflecting the deviation degree of the temperature at this time. Within the preset previous range at this moment, calculate the average rate of decrease of the load-bearing state index and perform a negative correlation mapping to obtain the decrease adjustment degree. When the decrease speed is higher, the adjustment compensation is tighter. In the embodiment of the present invention, the preset previous range can be set to the range of the previous 10 moments before this moment. The ratio of the difference in the load-bearing state between the previous moment and the next moment to the time duration between the moments is the rate of decrease of the load-bearing state index, and the average value of all rates within the preset previous range is used as the average rate of decrease of the load-bearing state index.

[0037] Furthermore, by combining the temperature deviation degree and the decrease adjustment degree, the threshold adjustment coefficient at this moment is obtained. In the embodiment of the present invention, the product of the temperature deviation degree and the decrease adjustment degree is normalized to obtain the threshold adjustment coefficient, where the normalization range is [-1, 1]. For different situations of temperature deviation, the sensitivity of the adjustment system required at this time is characterized by the threshold adjustment coefficient.

[0038] Finally, after multiplying the preset rate threshold by the threshold adjustment coefficient, calculate the sum of the product and the preset rate threshold as the adjusted creep rate threshold at this moment. The product of the preset rate threshold and the threshold adjustment coefficient is used as the adjustment amount to adjust the preset rate threshold. It should be noted that the preset rate threshold is regulated by the implementer according to the specific implementation scenario and can be set to 0.005, which is not limited here.

[0039] After realizing the threshold adjustment at different temperatures, the static load is adjusted according to the exceeding situation of the change rate, so as to reduce the degree to which the mechanical properties of the polyurethane composite material mask the true bearing life assessment when fluctuating violently with temperature. Preferably, in the embodiment of the present invention, the method for obtaining the static load at the next moment includes: Calculate the change rate of the load-bearing state value between each moment and the previous moment as the creep rate at each moment, and characterize the creep rate through the speed of state change. In the embodiment of the present invention, the ratio of the difference in the load-bearing state value between each moment and the previous moment to the time duration between the moments is used as the change rate, that is, the creep rate.

[0040] When the creep rate is greater than or equal to the adjusted creep rate threshold, it indicates that the creep rate is too high and there may be a risk of direct fracture of the material, so adjustment is required. The ratio of the difference between the creep rate at this time and the adjusted creep rate threshold to the adjusted creep rate threshold is used as the adjustment ratio. The higher the excess amount of the creep rate, the more load reduction is required.

[0041] Furthermore, the product of the value obtained by negatively correlating the load-bearing state value at the corresponding moment and the adjustment ratio is used as the load adjustment coefficient at this moment. Considering the load-bearing state at this time, the worse the load-bearing state, the higher the degree of adjustment required to ensure the stable and complete progress of the test. Finally, multiply the static load at this moment by the load adjustment coefficient, and calculate the difference between the static load at this moment and the product as the static load at the next moment. By reducing the load, the overall stability of the test is ensured, and thus a more realistic anti-creep situation of the electric pole can be evaluated.

[0042] In the embodiment of the present invention, an anti-creep index is obtained according to the change of the static load and the load-bearing state value at each moment, including: For each moment, the difference in static load between each moment and the next moment is used as the adjustment amplitude for each moment. The value obtained by negatively correlating the load-bearing state at each moment with the adjustment amplitude is multiplied for normalization processing to obtain the anti-creep index for each moment. For a polyurethane composite material electric pole, when the load amplitude to be adjusted is smaller at this time and the load-bearing state is better, it reflects that the anti-deformation ability of the electric pole is better, that is, the anti-creep index is larger.

[0043] S3: Based on the correlation relationship between the load-bearing state value and the temperature in time series, and the correction of the dynamic load amplitude due to the current temperature change, the dynamic load amplitude at the next moment is obtained; the dynamic load frequency at the next moment is obtained by adjusting the dynamic load frequency according to the change rate fluctuation of the current load-bearing state value; according to the load-bearing state value at each moment, and the previous dynamic load amplitude and dynamic load frequency distribution, the anti-fatigue index at the moment is obtained.

[0044] For the fatigue test of the polyurethane composite material electric pole, it is carried out by dynamically changing the load parameters, that is, changing the amplitude and frequency. Considering the influence of continuous wind gusts in the field environment of the electric pole, the life of the electric pole is evaluated through repeated stress conditions. However, the process of the fatigue test of the electric pole is still affected by temperature, and at the same time, the load parameters during the fatigue test are also affected by the creep test process. Since the creep test will cause the electric pole to deform slowly, the anti-fatigue ability of the electric pole gradually decreases. When the creep rate is too high, the deformation amount of the material in each fatigue cycle will increase, which may cause the material to accumulate too much deformation in a short time, thereby accelerating the expansion of fatigue cracks and making the test results tend to a shorter fatigue life.

[0045] As the temperature rises, the elastic modulus of polyurethane decreases and the deformation increases under the same load, leading to unrealistic accelerated damage. Therefore, the dynamic load parameters are reduced in combination with the load-bearing state of the pole at temperature, and the test is conducted at a more realistic strain level when the pole is in service, thereby improving the accuracy of subsequent life assessment.

[0046] In an embodiment of the present invention, a method for obtaining the dynamic load amplitude at a later moment includes: First, for any moment, in the time sequence before the moment, a two-dimensional coordinate system is constructed based on the temperature and the load state value at the moment. In the two-dimensional coordinate system, the horizontal axis is the temperature and the vertical axis is the load state value. The correlation between the temperature and the load state is analyzed through the two-dimensional coordinates. Each moment is mapped to the two-dimensional coordinate system and a straight line is fitted. The slope of the fitted straight line is used as the temperature sensitivity coefficient to reflect the degree of change in the load state index caused by a unit temperature change. It should be noted that straight line fitting and slope acquisition are both well-known technical means well known to those skilled in the art, and will not be elaborated here.

[0047] Then, load correction is performed through real-time changes combined with sensitivity coefficients. After calculating the temperature difference between this moment and the previous moment, the ratio of the temperature difference to the temperature at this moment is taken as the temperature change degree, and the product of the temperature change degree and the temperature sensitivity coefficient is taken as the temperature adjustment coefficient. By analyzing the real-time temperature change degree, the influence of the load state is adjusted. The greater the temperature change, the more drastic the material state change, and the greater the load adjustment is required.

[0048] Finally, after multiplying the temperature adjustment coefficient by the dynamic load amplitude at that moment, the difference between the dynamic load amplitude at that moment and the product is calculated as the dynamic load amplitude at the next moment.

[0049] At the same time, the dynamic load frequency is adjusted. Since creep will weaken fatigue resistance, the test rhythm needs to be slowed down. Therefore, in the embodiment of the present invention, the method for obtaining the dynamic load frequency at the next moment includes: The difference between the creep rate at each moment and the historical average creep rate and the ratio of the historical average creep rate are used as the frequency adjustment coefficient at each moment. The historical average creep rate is the average of the creep rates at all moments before each moment. The larger the creep rate, the lower the frequency of the fatigue test. After multiplying the dynamic load frequency at each moment by the frequency adjustment coefficient, the difference between the dynamic load frequency and the product is calculated as the dynamic load frequency at the next moment.

[0050] By testing the cumulative fatigue degree combined with the state index up to the current moment, the anti-fatigue ability of the pole is reflected. Preferably, in the embodiment of the present invention, the method for obtaining the anti-fatigue index includes: For any given moment, by combining all the dynamic load amplitudes, dynamic load frequencies, and test durations before that moment, a cumulative index for that moment is obtained. In the embodiments of the present invention, the mean value of all the dynamic load amplitudes before that moment is used as the average dynamic load amplitude. The larger this value is, the stronger the material's ability to withstand high loads. The mean value of all the dynamic load frequencies before that moment is used as the average dynamic load frequency. The larger this value is, the better the anti-high-frequency fatigue ability. The duration from that moment back to the start of the test is used as the test duration. The longer the duration, the better the lifespan. Therefore, the product of the average dynamic load amplitude, the average dynamic load frequency, and the test duration is used as the cumulative index. The larger the cumulative index, the better the anti-fatigue performance.

[0051] Finally, the product of the cumulative index and the load-bearing state value at that moment is normalized to obtain the anti-fatigue index at that moment. When the load-bearing state value is larger, it reflects a lower degree of damage. Combining the cumulative index to obtain the anti-fatigue index, the larger the anti-fatigue index, the better the fatigue performance.

[0052] S4: Determine the stop moment according to the size of the load-bearing state index; through the trend changes of the anti-creep index and the anti-fatigue index before the stop moment, combined with the distribution of the load-bearing state value and the load deviation distribution under deformation, obtain the load-bearing capacity test result.

[0053] When the cracks on the surface of the pole or the deformation of the pole reach a certain degree, the test can be stopped, that is, the load-bearing capacity of the pole reaches the limit. At this time, the final load-bearing capacity of the polyurethane composite pole is evaluated according to the data obtained during the test.

[0054] In the embodiments of the present invention, when the load-bearing state value of the pole is less than or equal to the preset stop threshold, it is considered that the load-bearing capacity of the pole has reached the limit, and the test is stopped, and this moment is recorded as the stop moment. The preset stop threshold is set to 0.3, and the specific value can be adjusted by the implementer.

[0055] Based on the anti-creep index and the anti-fatigue index analyzed after the test stop, comprehensively consider the load-bearing situation of the pole from the perspective of service life, and further consider the degree of load application after the pole undergoes obvious deformation, reflecting the persistence of the pole to the limit, that is, characterizing the toughness of the pole. Therefore, from the anti-creep index and the anti-fatigue index after the test, as well as the load deviation after deformation, combined with the overall load-bearing state value, the test result is obtained.

[0056] In the embodiments of the present invention, in the time series before the stop moment, a linear fit is performed on the numerical distribution of the anti-creep index in the time series, and the fitting slope is negatively correlated and mapped to obtain the creep life evaluation value. A linear fit is performed on the numerical distribution of the anti-fatigue index in the time series, and the fitting slope is negatively correlated and mapped to obtain the fatigue life evaluation value. As the pole approaches the limit, the bearing condition becomes worse, and the anti-creep index and anti-fatigue index also become smaller. Fitting the numerical values in the continuous time series reflects the degree of trend through the magnitude of the slope. When the slope value is smaller, it indicates that the exponential decay is slower, and the service life of the pole is longer.

[0057] Therefore, by combining the creep life evaluation value and the fatigue life evaluation value, a life evaluation index is obtained. In the embodiments of the present invention, the product of the creep life evaluation value and the fatigue life evaluation value is used as the life evaluation index. The larger the life evaluation index, the better the bearing capacity.

[0058] Furthermore, the difference between the load at the moment of deformation start and the maximum load between the start and stop moments of deformation is negatively correlated and mapped to obtain the toughness evaluation index. When the load at the start of deformation is closer to the load at stop, it indicates that the process of the material from deformation to the fracture limit is smaller, the toughness of the pole is better, and the overall bearing condition is better.

[0059] Finally, by combining all the bearing state values, life evaluation index, and toughness evaluation index in the time series, a bearing capacity index is obtained as the bearing capacity test result. In the embodiments of the present invention, the mean value of all the bearing state values in the time series before the stop moment is used as the average bearing state, which reflects the average bearing state during the entire test. The larger the average bearing state, the better the overall performance of the pole. Therefore, the product of the average bearing state, life evaluation index, and toughness evaluation index is normalized to obtain the bearing capacity index as the bearing capacity test result, integrating the three factors of life, toughness, and state. The larger the bearing capacity index, the better the comprehensive bearing capacity.

[0060] In the embodiments of the present invention, subsequently, it can be determined whether it meets the standard based on the bearing capacity test result, and it is judged whether the long-term service requirements are met by the magnitude of the bearing capacity index. When the bearing capacity index is lower than the expected design value, the risk level needs to be evaluated. At the same time, if the polyurethane composite pole is damaged, the failure mode is determined according to the damage state and the improvement direction is determined. For example, when brittle fracture occurs, that is, there is no plastic deformation at low temperature, the material formula needs to be optimized or a toughening agent needs to be added. When ductile failure occurs, that is, there is large-scale deformation at high temperature, the matrix stiffness needs to be increased or the service temperature needs to be reduced. When fatigue crack propagation occurs, the manufacturing process needs to be inspected, such as checking the fiber layup uniformity or adding local reinforcement, etc.

[0061] In summary, through the physical characteristic deformation in the bearing capacity test of the pole under temperature changes, static load and dynamic load tests are carried out simultaneously, which is convenient for analyzing the long-term service life of the pole from the perspectives of creep resistance and fatigue resistance, so as to more comprehensively test the load capacity of the pole under complex conditions. First, the bearing state is characterized by the deformation performance at a certain moment. After adjusting the creep rate threshold from the temperature change and the decrease in the real-time bearing state, the static load is adjusted through the offset of the change rate of the bearing state at a certain moment. Considering the change in the creep rate caused by the influence of temperature on the internal activity of the material, overloading and accelerating damage are avoided, which affects the bearing evaluation. Combining the change in the static load and the bearing state, the creep resistance index is obtained. Further, from the correlation between temperature and bearing state in time series, and the correction of the dynamic load amplitude by the temperature change at a certain moment, considering the decrease in the material modulus at high temperature, the dynamic load amplitude needs to be adjusted to adapt to the actual working conditions. And through the change rate of the bearing state value, the dynamic load frequency is adjusted, considering the weakened fatigue situation in creep analysis, so as to adjust the rhythm of the fatigue resistance test. Finally, by comprehensively considering the accumulated state in time series and the bearing state at a certain moment, the fatigue resistance index is obtained. After the limit of the real-time bearing state stops, through the trend of creep resistance and fatigue resistance in the test, combined with the bearing state and the load change that generates deformation, the bearing test result is comprehensively obtained. Considering the creep life, fatigue life, toughness of the deformed load, and the bearing state of the three factors, a better bearing capacity test result is comprehensively obtained. The present invention combines dynamic fatigue and creep tests with temperature changes, dynamically adjusts the load parameters according to the real-time temperature and the real-time pole state during the test, more comprehensively tests the load capacity of the pole in different environments, and obtains a more accurate bearing capacity test result of the pole.

[0062] It should be noted that the above sequence of embodiments of the present invention is only for description and does not represent the superiority or inferiority of the embodiments. The processes depicted in the drawings do not necessarily require the specific order or continuous order shown to achieve the desired result. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0063] Each embodiment in this specification is described in a progressive manner, and the same or similar parts among the embodiments can be referred to each other. Each embodiment focuses on the differences from other embodiments.

Claims

1. A method for testing the bearing capacity of a polyurethane composite pole, characterized in that, The method includes: In the variable temperature bearing capacity test, obtain the temperature, various deformation parameters, static load, dynamic load amplitude, and dynamic load frequency of the electric pole at each moment; obtain the bearing state value at each moment according to the various deformation parameters at each moment. Adjust the creep rate threshold according to the temperature change and the degree of reduction of the bearing state value at the moment; analyze the deviation of the change rate of the bearing state value based on the currently adjusted creep rate threshold, and correct the static load in combination with the bearing state value to obtain the static load at the next moment; obtain the anti-creep index at the moment according to the change of the static load and the bearing state value at each moment. Based on the correlation relationship between the bearing state value and the temperature in time series, and correct the dynamic load amplitude according to the current temperature change to obtain the dynamic load amplitude at the next moment; adjust the dynamic load frequency by the fluctuation of the change rate of the current bearing state value to obtain the dynamic load frequency at the next moment; obtain the anti-fatigue index at the moment according to the bearing state value at each moment, and the distribution of the previous dynamic load amplitude and dynamic load frequency. Determine the stop moment according to the size of the bearing state index; obtain the bearing capacity test result by the trend changes of the anti-creep index and the anti-fatigue index in the previous sequence before the stop moment, in combination with the bearing state value distribution and the load deviation distribution under deformation.

2. The bearing capacity test method of a polyurethane composite material electric pole according to claim 1, characterized in that, The method for obtaining the bearing state includes: The deformation parameters include the crack area, the strain values at all positions on the electric pole, and the displacement of the stay plate. For any moment, perform negative correlation mapping and normalization on the variance of the strain values at all positions at this moment to obtain the strain bearing degree; perform negative correlation mapping and normalization on the displacement of the stay plate at this moment to obtain the displacement bearing degree; perform weighted summation on the strain bearing degree and the displacement bearing degree at this moment to obtain the deformation bearing capacity at this moment. Perform normalization on the product of the value obtained by negative correlation mapping of the crack area at this moment and the deformation bearing capacity to obtain the bearing state value at this moment.

3. The bearing capacity testing method of a polyurethane composite pole according to claim 1, characterized in that The adjustment of the creep rate threshold according to the temperature change and the degree of reduction of the bearing state value at the moment includes: For any moment, take the difference between the temperature at this moment and the previous average temperature as the temperature offset degree at this moment. Within the preset previous sequence range at this moment, calculate the average rate of reduction of the bearing state index and perform negative correlation mapping to obtain the reduction adjustment degree. Combine the temperature offset degree and the reduction adjustment degree to obtain the threshold adjustment coefficient at this moment; multiply the preset rate threshold by the threshold adjustment coefficient, and calculate the sum of the product and the preset rate threshold as the adjusted creep rate threshold at this moment.

4. The bearing capacity test method of a polyurethane composite material electric pole according to claim 1, characterized in that, The method for obtaining the static load at the next moment includes: Calculate the change rate of the bearing state value between each moment and the previous moment as the creep rate at each moment. When the creep rate is greater than or equal to the adjusted creep rate threshold, take the ratio of the difference between the creep rate and the adjusted creep rate threshold to the adjusted creep rate threshold as the adjustment ratio; take the product of the value obtained by negative correlation mapping of the bearing state value at the corresponding moment and the adjustment ratio as the load adjustment coefficient at this moment; multiply the static load at this moment by the load adjustment coefficient, and calculate the difference between the static load at this moment and the product as the static load at the next moment.

5. The bearing capacity test method of a polyurethane composite material electric pole according to claim 1, characterized in that, The method for obtaining the anti-creep index includes: For each moment, the difference in static load between each moment and the next moment is taken as the adjustment amplitude for each moment; The value obtained by multiplying the bearing state at each moment by the value obtained by negatively correlating the mapping of the adjustment amplitude is used to obtain the anti-creep index at each moment.

6. The bearing capacity test method of a polyurethane composite material pole according to claim 1, characterized in that, The method for obtaining the dynamic load amplitude at the next moment includes: For any moment, in the time sequence before this moment, a two-dimensional coordinate system is constructed based on the temperature and bearing state value at the moment; the horizontal axis in the two-dimensional coordinate system is temperature, and the vertical axis is the bearing state value; each moment is mapped into the two-dimensional coordinate system and linearly fitted, and the slope of the fitted line is used as the temperature sensitivity coefficient; After calculating the temperature difference between this moment and the previous moment, the ratio of the temperature difference to the temperature at this moment is used as the temperature change degree; the product of the temperature change degree and the temperature sensitivity coefficient is used as the temperature adjustment coefficient; after multiplying the temperature adjustment coefficient by the dynamic load amplitude at this moment, the difference between the dynamic load amplitude at the moment and the product is calculated as the dynamic load amplitude at the next moment.

7. The bearing capacity test method of a polyurethane composite material pole according to claim 4, characterized in that, The method for obtaining the dynamic load frequency at the next moment includes: The ratio of the difference between the creep rate at each moment and the historical average creep rate to the historical average creep rate is used as the frequency adjustment coefficient at each moment; After multiplying the dynamic load frequency at each moment by the frequency adjustment coefficient, the difference between the dynamic load frequency and the product is calculated as the dynamic load frequency at the next moment.

8. The bearing capacity test method of a polyurethane composite material electric pole according to claim 1, characterized in that, The method for obtaining the anti-fatigue index includes: For any moment, by combining all the dynamic load amplitudes, dynamic load frequencies, and test durations before this moment, the cumulative index at this moment is obtained; the product of the cumulative index and the bearing state value at this moment is normalized to obtain the anti-fatigue index at this moment.

9. The bearing capacity test method of a polyurethane composite material pole according to claim 1, characterized in that, The method for obtaining the bearing capacity test result includes: In the time sequence before the stop moment, the numerical distribution of the anti-creep index in the time sequence is linearly fitted, and the fitted slope is negatively correlated and mapped to obtain the creep life evaluation value; the numerical distribution of the anti-fatigue index in the time sequence is linearly fitted, and the slope of the fit is negatively correlated and mapped to obtain the fatigue life evaluation value; Combining the creep life evaluation value and the fatigue life evaluation value to obtain the life evaluation index; The difference between the load at the deformation start moment and the maximum load between the deformation start and stop moments is negatively correlated and mapped to obtain the toughness evaluation index; Combining all the bearing state values, life evaluation indexes, and toughness evaluation indexes in the time sequence to obtain the bearing capacity index as the bearing capacity test result.

10. A bearing capacity testing device for a polyurethane composite material electric pole, characterized in that, It includes a temperature control module and a variable temperature test module. The temperature control module is used to control the temperature change; the variable temperature test module includes a collection unit, an analysis and control unit, and a test evaluation unit; The signal output end of the collection unit is connected to the signal input end of the analysis and control unit, the signal output end of the analysis and control unit is connected to the signal input end of the test evaluation unit. The analysis and control unit is used for data analysis and regulating the subsequent load; the test evaluation unit is used for evaluating the test result; The collection unit obtains the temperature, various deformation parameters, static load, dynamic load amplitude, and dynamic load frequency at each moment through sensors, and transmits the obtained data to the analysis and control unit; The analysis and control unit obtains the load-bearing state value at each moment according to the deformation parameters at each moment; Adjust the creep rate threshold according to the temperature change and the reduction degree of the load-bearing state value at the moment; Analyze the deviation of the change rate of the load-bearing state value based on the currently adjusted creep rate threshold, and correct the static load in combination with the load-bearing state value to obtain the static load at the next moment; Obtain the anti-creep index at the moment according to the static load change and the load-bearing state value at each moment; Based on the correlation between the load-bearing state value and the temperature in time series, and the correction of the dynamic load amplitude by the current temperature change, obtain the dynamic load amplitude at the next moment; Adjust the dynamic load frequency by the fluctuation of the change rate of the current load-bearing state value to obtain the dynamic load frequency at the next moment; Obtain the anti-fatigue index at the moment according to the load-bearing state value at each moment and the previous dynamic load amplitude and dynamic load frequency distribution; Determine the stop moment according to the size of the load-bearing state index; Transmit the analysis data before the stop moment to the test and evaluation unit; The test and evaluation unit obtains the bearing capacity test result by the trend changes of the anti-creep index and the anti-fatigue index in the previous order of the stop moment, in combination with the load-bearing state value distribution and the load deviation distribution under deformation.

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