A bearing capacity testing device and testing method for polyurethane composite poles

Abstract

The present invention relates to the technical field of bearing capacity testing, and in particular to a bearing capacity testing device and testing method for a polyurethane composite pole. The method characterizes the bearing state according to the deformation performance at a given moment, adjusts the creep threshold from the temperature change and the bearing state reduction change, and then analyzes the offset of the bearing state change to correct the static load; obtains the anti-creep index by combining the static load change and the bearing state; adjusts the dynamic load frequency by the rate of change of the bearing state from the correlation between the temperature and the bearing state in the time sequence, and the temperature change to correct the dynamic load amplitude, and obtains the anti-fatigue index by combining the bearing state; obtains the bearing test results by combining the deformation and the bearing state through the trend of anti-creep and anti-fatigue. The present invention dynamically adjusts the load parameters by combining the dynamic fatigue and creep tests of temperature changes, and more comprehensively tests the load capacity of the pole in different environments, thereby obtaining more accurate pole bearing capacity test results.

Description

Technical Field

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

[0002] Polyurethane (PU), also known as polyurethane, is a polymer material formed by the polycondensation reaction of polyols and polyisocyanates. It exhibits excellent mechanical properties and boasts exceptional plasticity. Polyurethane composite poles are a novel pole material manufactured using a specific process, using polyurethane as a carrier and glass fiber as reinforcement. Poles made from this material are widely used in transmission lines, distribution systems, and other fields due to their advantages of easy installation, low maintenance costs, high safety, and environmental protection and energy conservation.

[0003] Power poles typically operate outdoors. Under extreme conditions, such as extreme weather (strong winds, heavy rain, snowstorms, ice storms, etc.) or geological disasters (such as earthquakes), the loads they bear can far exceed those encountered during normal operation. Load-bearing tests can help assess the load-bearing capacity of power poles under these extreme conditions, verifying their safety to address potential risks and ensuring the continuity and reliability of power supply in harsh environments.

[0004] Polyurethane composite materials have the characteristics of high toughness and low stiffness, and are prone to plastic deformation or crack propagation. In addition, this material is highly sensitive to temperature, and exhibits the characteristics of low-temperature brittleness and high-temperature softening. However, when conducting load-bearing capacity tests on electric poles, existing devices usually do not consider the impact of extreme weather and mainly conduct tests in a stable environment. In order to improve the test efficiency during the test process, static or high-frequency dynamic tests are mainly performed on the electric poles. For example, fatigue tests above 50Hz on electric poles do not consider the influence of temperature changes and load capacity in complex environments. Therefore, it is impossible to effectively evaluate its long-term service performance, resulting in inaccurate load-bearing capacity test results for the electric poles. Summary of the Invention

[0005] In order to solve the technical problems that the existing technology does not consider the influence of temperature changes and load capacity in complex environments, cannot effectively evaluate the long-term service performance, and the bearing capacity test results of electric poles are inaccurate, the purpose of the present invention is to provide a bearing capacity test device and test method for polyurethane composite electric poles. The technical solutions adopted are as follows:

[0006] The present invention provides a method for testing the bearing capacity of a polyurethane composite material electric pole, the method comprising:

[0007] In the variable temperature bearing capacity test, the temperature, deformation parameters, static load, dynamic load amplitude and dynamic load frequency of the pole at each moment are obtained; based on the deformation parameters at each moment, the bearing state value at each moment is obtained;

[0008] Adjust the creep rate threshold based on the temperature change and the degree of reduction in the load state value at that moment; analyze the offset of the load state value change rate based on the current adjusted creep rate threshold, and correct the static load in combination with the load state value to obtain the static load at the next moment; obtain the creep resistance index at each moment based on the static load change and the load state value at each moment;

[0009] Based on the correlation between the load state value and temperature in the 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 is adjusted by the fluctuation of the change rate of the current load state value to obtain the dynamic load frequency at the next moment; based on the load state value at each moment, as well as the distribution of the previous dynamic load amplitude and dynamic load frequency, the fatigue resistance index at the moment is obtained;

[0010] The stopping time is determined according to the size of the load-bearing state index; the load-bearing capacity test results are obtained by analyzing the trend changes of the creep resistance index and fatigue resistance index before the stopping time, combined with the distribution of the load state value and the load deviation distribution under deformation.

[0011] Furthermore, the method for obtaining the bearer status includes:

[0012] The deformation parameters include the crack area, the strain values ​​at all positions on the pole, and the support plate displacement;

[0013] For any moment, the variance of the strain values ​​at all positions at that moment is negatively correlated and normalized to obtain the strain bearing capacity; the support plate displacement at that moment is negatively correlated and normalized to obtain the displacement bearing capacity; the strain bearing capacity and the displacement bearing capacity at that moment are weighted summed to obtain the deformation bearing capacity at that moment;

[0014] The product of the negative correlation mapping value of the crack area at that moment and the deformation bearing capacity is normalized to obtain the bearing state value at that moment.

[0015] Furthermore, adjusting the creep rate threshold according to the temperature change at a given moment and the degree of reduction in the load state value includes:

[0016] For any moment, the difference between the temperature at that moment and the previous average temperature is taken as the temperature offset at that moment;

[0017] Within the preset pre-order range at that moment, the average rate of reduction of the load status indicator is calculated and negative correlation mapping is performed to obtain the reduction adjustment degree;

[0018] The threshold adjustment coefficient at that moment is obtained by combining the temperature offset and the reduction adjustment degree; after multiplying the preset rate threshold by the threshold adjustment coefficient, the sum of the product and the preset rate threshold is calculated as the adjustment creep rate threshold at that moment.

[0019] Furthermore, the method for obtaining the static load at the next moment includes:

[0020] Calculate the rate of change of the load state value between each moment and the previous moment as the creep rate at each moment;

[0021] When the creep rate is greater than or equal to the adjusted creep rate threshold, the difference between the creep rate and the adjusted creep rate threshold and the ratio of the adjusted creep rate threshold are used as the adjustment ratio; the product of the value of the negative correlation mapping of the load 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.

[0022] Furthermore, the method for obtaining the creep resistance index includes:

[0023] For each moment, the difference in static load between each moment and the next moment is taken as the adjustment amplitude at each moment;

[0024] The anti-creep index at each moment is obtained by multiplying the value of the negative correlation mapping between the load state and the adjustment amplitude at each moment.

[0025] Furthermore, the method for obtaining the dynamic load amplitude at the next moment includes:

[0026] For any moment, a two-dimensional coordinate system is constructed based on the temperature and load state value at that moment in the time series before that moment. The horizontal axis of the two-dimensional coordinate system is the temperature, and the vertical axis is the load state value. Each moment is mapped to the two-dimensional coordinate system and a straight line is fitted. The slope of the fitted line is used as the temperature sensitivity coefficient.

[0027] After calculating the temperature difference between the current moment and the previous moment, the ratio of the temperature difference to the temperature at that moment is taken as the temperature change degree; the product of the temperature change degree and the temperature sensitivity coefficient is taken 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 the current moment and the product is calculated as the dynamic load amplitude at the next moment.

[0028] Furthermore, the method for obtaining the dynamic load frequency at the next moment includes:

[0029] The difference between the creep rate at each moment and the historical average creep rate, and the ratio of the difference to the historical average creep rate are used as the frequency adjustment coefficient at each moment;

[0030] 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.

[0031] Furthermore, the method for obtaining the anti-fatigue index includes:

[0032] For any moment, the cumulative index at that moment is obtained by combining all dynamic load amplitudes, dynamic load frequencies and test durations before that moment; the product of the cumulative index and the load state value at that moment is normalized to obtain the fatigue resistance index at that moment.

[0033] Furthermore, the method for obtaining the bearing capacity test result includes:

[0034] In the time series before the stop moment, a linear fit is performed on the numerical distribution of the creep resistance index in the time series, and the fitting slope is negatively correlated to obtain the creep life evaluation value; a linear fit is performed on the numerical distribution of the fatigue resistance index in the time series, and the fitting slope is negatively correlated to obtain the fatigue life evaluation value;

[0035] Combining creep life assessment value and fatigue life assessment value to obtain life assessment index;

[0036] The difference between the load at the start of deformation and the maximum load between the start and stop of deformation is negatively correlated to obtain the toughness evaluation index;

[0037] Combining all the load-bearing state values, life evaluation indicators and toughness evaluation indicators in the time series, the load-bearing capacity index is obtained as the load-bearing capacity test result.

[0038] The present invention also provides a bearing capacity testing device for a polyurethane composite pole, comprising a temperature control module and a variable temperature testing module, wherein the temperature control module is used to control temperature changes; the variable temperature testing module comprises a collection unit, an analysis and control unit, and a test evaluation unit;

[0039] The signal output end of the acquisition unit is connected to the signal input end of the analysis control unit, and the signal output end of the analysis control unit is connected to the signal input end of the test evaluation unit. The analysis control unit is used for data analysis and regulating subsequent loads; the test evaluation unit is used for evaluating test results;

[0040] The acquisition unit acquires 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 control unit;

[0041] The analysis control unit obtains the load state value at each moment based on the deformation parameters at each moment; adjusts the creep rate threshold based on the temperature change and the degree of reduction in the load state value at that moment; analyzes the offset of the load state value change rate based on the currently adjusted creep rate threshold, and corrects the static load based on the load state value to obtain the static load at the next moment; and obtains the creep resistance index at the moment based on the static load change and the load state value at each moment;

[0042] Based on the correlation between the load state value and temperature in the 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 is adjusted by the fluctuation of the change rate of the current load state value to obtain the dynamic load frequency at the next moment; based on the load state value at each moment, as well as the distribution of the previous dynamic load amplitude and dynamic load frequency, the fatigue resistance index at the moment is obtained;

[0043] Determine the stopping time according to the size of the load status indicator; transmit the analysis data before the stopping time to the test evaluation unit;

[0044] The test evaluation unit obtains the bearing capacity test results by combining the trend changes of the creep resistance index and fatigue resistance index before the stopping moment with the distribution of the bearing state value and the load deviation distribution under deformation.

[0045] The present invention has the following beneficial effects:

[0046] This method utilizes the physical deformation characteristics of poles during temperature-dependent load-bearing capacity testing to simultaneously conduct static and dynamic load tests. This facilitates analysis of the long-term service life of poles from the perspectives of creep resistance and fatigue resistance, thereby providing a more comprehensive assessment of the pole's load-bearing capacity under complex conditions. First, the load-bearing state is characterized by deformation at any given moment. After adjusting the creep rate threshold based on the temperature change and the decrease in the real-time load-bearing state, the static load is adjusted based on the offset of the load-bearing state change rate at that moment. This considers the creep rate changes caused by temperature's impact on the material's internal activity, preventing overload from accelerating damage and affecting the load-bearing assessment. Combining the static load change and load-bearing state, a creep resistance index is derived. Furthermore, the temporal correlation between temperature and load-bearing state, as well as the dynamic load amplitude corrections based on temperature changes at that moment, are used to account for the decrease in material modulus at high temperatures. The dynamic load amplitude needs to be adjusted to suit actual operating conditions. The dynamic load frequency is then adjusted based on the rate of change of the load-bearing state value, taking into account the fatigue reduction caused by creep analysis to adjust the fatigue resistance test rhythm. Finally, the fatigue resistance index is derived by combining the accumulated temporal state and the load-bearing state at that moment. After the real-time load-bearing state reaches its limit, the load-bearing test results are obtained by combining the creep and fatigue resistance trends during the test with the load state and the load changes that produce deformation. Taking into account the creep life and fatigue life, the toughness of the deformation load, and the load state, a more optimal load-bearing capacity test result is obtained. The present invention combines dynamic fatigue and creep testing with temperature changes, dynamically adjusting the load parameters according to the real-time temperature and real-time pole state during the test process, more comprehensively testing the load capacity of the pole under different environments and obtaining more accurate pole load-bearing capacity test results. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the technical solutions and advantages of the embodiments of the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the prior art descriptions. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0048] Figure 1 A flow chart of a method for testing the bearing capacity of a polyurethane composite pole provided by one embodiment of the present invention;

[0049] Figure 2 A schematic structural diagram of a polyurethane composite material pole bearing capacity testing device provided by one embodiment of the present invention;

[0050] Figure 3 A schematic structural diagram of a testing platform provided by one embodiment of the present invention;

[0051] Figure 4A schematic diagram of a cover plate structure provided by one embodiment of the present invention;

[0052] Figure 5 A schematic diagram of a protective frame structure provided by one embodiment of the present invention;

[0053] Figure 6 A structural schematic diagram of the installation position of a distributed fiber Bragg grating sensor provided by one embodiment of the present invention;

[0054] Figure 7 A schematic diagram of applying a static load and a dynamic load provided by one embodiment of the present invention;

[0055] Figure 8 A schematic diagram of a strain value distribution curve provided by one embodiment of the present invention;

[0056] In conjunction with the accompanying drawings, the following reference numerals are marked on the drawings: 1. Test table; 10. Slide; 11. Guide rod; 12. First hydraulic cylinder; 2. Bottom placement table; 20. Internal insert; 3. Slider; 30. Corrosion-resistant steel pipe; 31. Sleeve plate; 32. Fan-shaped support plate; 33. Displacement sensor; 4. Protection frame; 40. Protection net; 41. Visual sensor; 42. Acoustic emission sensor; 50. Magnetic induction patch; 5. Indicator light; 60. Hinge; 6. Cover plate; 61. Pressure test box; 62. Second hydraulic cylinder; 70. Control rod; 7. Pressure plate; 71. Connecting rod; 72. Pressure sensor probe plate; 73. Iron indicator tube; 74. Distributed fiber Bragg grating sensor; 8. Electric servo actuator; 9. Temperature control module; 33. Displacement sensor; 41. Visual sensor; 42. Acoustic emission sensor; 74. Distributed fiber Bragg grating sensor. DETAILED DESCRIPTION

[0057] To further illustrate the technical means and effectiveness of the present invention in achieving its intended objectives, the following, in conjunction with the accompanying drawings and preferred embodiments, describes in detail the specific implementation, structure, features, and effectiveness of a polyurethane composite pole load-bearing capacity testing device and method proposed by the present invention. In the following description, references to different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics of one or more embodiments may be combined in any suitable manner.

[0058] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0059] The following describes in detail the specific scheme of the bearing capacity testing device and testing method of the polyurethane composite material electric pole provided by the present invention in conjunction with the accompanying drawings. Figures 2 to 6In a bearing capacity testing device for a polyurethane composite pole, a temperature control module 9 is installed inside a test bench 1 and includes a PTC heating plate and a liquid cooling circulation pipe for controlling temperature changes; an electric servo actuator 8 is installed on a second hydraulic cylinder 62 for controlling load output; a distributed fiber grating sensor 74 is installed on the bottom of a pressure plate 7 for obtaining the surface strain distribution of the polyurethane pole in real time; a displacement sensor 33 is installed inside a fan-shaped support plate 32 for obtaining the support plate displacement in real time and quantifying the expansion deformation amplitude inside the pole; a visual sensor 41 is installed on a protective frame 4 for collecting image information of the pole surface in real time; and an acoustic emission sensor 42 is installed on the protective frame 4 for collecting signals of pole material delamination or fiber breakage in real time.

[0060] The temperature control module 9 uses an artificial intelligence algorithm to simulate temperature changes in daily environments and temperature changes in extreme weather. For example, when simulating the day and 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 range is obtained for different seasons. For example, the average temperature in spring is between 5°C and 20°C. It is understandable that the implementer of the specific temperature control situation can adjust it according to the specific implementation scenario, and there is no limitation here.

[0061] Place the polyurethane composite pole into the device, and by adjusting the first hydraulic cylinder 12, the second hydraulic cylinder 62, the fan-shaped support plate 32, the pressure plate 7 and other components, fix the pole in the device for variable temperature bearing capacity testing. Before the test, clean the surface of the polyurethane composite pole to ensure the flatness of the sensor fitting area, and calibrate each sensor using existing instruments or existing methods to ensure that it can collect data normally. At the same time, make sure that the load output error of the first hydraulic cylinder 12, the second hydraulic cylinder 62 and the electric servo actuator is less than 2%. Combine creep testing and fatigue testing during the test. The creep test is to apply a static load to the pole by the electric servo actuator, and at the same time conduct a fatigue test, that is, superimpose a dynamic load on 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 applying a static load and a dynamic load provided by an embodiment of the present invention. The initial addition of the static load and the dynamic load can be adjusted by the implementer according to the specific implementation scenario and is not limited here.

[0062] A bearing capacity testing device for a polyurethane composite pole also includes a variable temperature testing module, which includes an acquisition unit, an analysis control unit, and a test evaluation unit. The signal output end of the acquisition unit is connected to the signal input end of the analysis control unit. After the acquired data is transmitted to the analysis control unit, the analysis control unit performs data analysis and adjusts the subsequent load of the test. The signal output end of the analysis control unit is connected to the signal input end of the test evaluation unit. The test data is evaluated by the test evaluation unit. The variable temperature testing module can be a conventional single-chip microcomputer or other processor chip, such as: FPGA, CPU, MCU, etc.

[0063] For analysis and evaluation of bearing capacity tests, please refer to Figure 1 , which shows a flow chart of a method for testing the bearing capacity of a polyurethane composite pole provided by one embodiment of the present invention, the method comprising the following steps:

[0064] S1: In the variable temperature bearing capacity test, the temperature, deformation parameters, static load, dynamic load amplitude and dynamic load frequency of the pole at each moment are obtained; based on the deformation parameters at each moment, the bearing state value at each moment is obtained.

[0065] As the bearing capacity test of the polyurethane composite pole progresses, cracks will gradually appear on the surface of the pole, and the internal stress distribution of the pole will gradually cause displacement and expansion. Combined with the real-time collection results of the sensor, the real-time bearing status index of the polyurethane composite pole is determined. The better the condition of the pole, the greater the bearing status index.

[0066] Therefore, the real-time load-bearing status is first determined by the deformation parameters of the pole. In this embodiment of the present invention, the deformation parameters include the crack area, the strain values ​​at all locations on the pole, and the displacement of the support plate. The crack area is obtained by segmenting the cracks using a semantic segmentation algorithm after capturing the surface image with a visual sensor. The total number of pixels in the crack area is used as the crack area. The larger the crack area, the worse the current load-bearing status of the pole may be.

[0067] The distribution of strain values ​​at all locations on the pole can reflect the load-bearing condition of the pole. When the strain distribution on the pole surface is more uniform, it means that the pole is still in the elastic stage and the load-bearing condition is better. Otherwise, it means that the pole has begun to become unbalanced and the load-bearing capacity has begun to decrease. The more uneven the distribution, the weaker the load-bearing capacity. Figure 8 , which shows a schematic diagram of a strain value distribution curve provided by one embodiment of the present invention. Therefore, at any moment, the variance of the strain values ​​at all locations at that moment is negatively correlated and normalized to obtain the strain bearing capacity. A smaller variance indicates a stronger bearing capacity.

[0068] At the same time, the support plate displacement represents the magnitude of the displacement occurring at the fan-shaped support plate. When support plate displacement occurs, it indicates that deformation has begun to occur within the pole, and the internal deformation becomes more pronounced as the displacement increases. Therefore, the support plate displacement at that moment is negatively correlated and normalized to obtain the displacement load-bearing capacity. When support plate displacement does not occur, the load-bearing capacity is better.

[0069] Since the influence of support plate displacement and strain distribution on the load-bearing state is different, if the strain on the pole surface is uneven when there is no displacement at the fan-shaped support plate, the load-bearing capacity is weak. If the strain on the pole surface is uniform when there is obvious displacement at the fan-shaped support plate, the load-bearing capacity is strong. The uniformity of strain distribution is more important than the degree of support plate displacement.

[0070] Therefore, the strain bearing capacity and the displacement bearing capacity at that moment are weightedly summed to obtain the deformation bearing capacity at that 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 values ​​can be adjusted by the implementers themselves and are not limited here.

[0071] Finally, combined with the occurrence of crack area, the product of the value of the negative correlation mapping of the crack area at that moment and the deformation bearing capacity is normalized to obtain the bearing state value at that moment. The better the state of the pole, the larger the corresponding bearing state value.

[0072] It should be noted that negative correlation mapping and normalization processing are both technical means well known to those skilled in the art. Negative correlation means that the dependent variable increases as the independent variable decreases. Negative correlation mapping can adopt inverse proportion or negative exponential power form, etc. The normalization option can be linear normalization or standard normalization, etc. The specific negative phase mapping and normalization methods are not limited or elaborated here.

[0073] S2: Adjust the creep rate threshold according to the temperature change and the degree of reduction of the load state value at the moment; analyze the offset of the load state value change rate based on the current adjusted creep rate threshold, and correct the static load in combination with the load state value to obtain the static load at the next moment; obtain the creep resistance index at the moment based on the static load change and the load state value at each moment.

[0074] Creep testing of polyurethane composite poles primarily involves applying a constant static load to the poles and observing their creep under the static load. Because the ambient temperature simulates real-world day-night and seasonal variations, and high temperatures increase the internal activity of the pole material, the creep rate accelerates. If the creep rate exceeds a certain threshold at different temperatures, it indicates imminent fracture, underestimating the actual load-bearing capacity. Therefore, the static load needs to be adjusted to prevent normal creep at high temperatures from being misinterpreted as failure.

[0075] Higher temperatures indicate a more active material and a higher degree of softening, requiring a higher threshold to tolerate normal deformation. Conversely, lower temperatures indicate a higher degree of brittleness, requiring increased sensitivity to detect brittle fracture risks. Furthermore, the speed of change in the load state is determined by the rate of decrease. A greater decrease indicates faster material damage, requiring a controlled adjustment of the threshold. A smaller decrease indicates slower material damage and a stronger material, allowing for greater sensitivity adjustment.

[0076] Therefore, preferably, in an embodiment of the present invention, adjusting the creep rate threshold according to the temperature change at a moment and the degree of reduction of the load state value includes:

[0077] At any moment, the difference between the temperature at that moment and the previous average temperature is used as the temperature offset at that moment, reflecting the degree of temperature deviation at that moment. Within the preset previous range of that moment, the average rate of reduction of the load state indicator is calculated and negatively correlated to obtain the reduction adjustment degree. The higher the reduction rate, the tighter the adjustment compensation. In an embodiment of the present invention, the preset previous range can be set to the range of 10 moments before the moment. The ratio of the load state difference between the previous moment and the next moment to the time length between the moments is used to determine the rate of reduction of the load state indicator. The average of all rates within the preset previous range is used as the average rate of reduction of the load state indicator.

[0078] Then, the temperature offset and the reduction adjustment degree are combined to obtain the threshold adjustment coefficient at that moment. In an embodiment of the present invention, the product of the temperature offset and the reduction adjustment degree is normalized to obtain the threshold adjustment coefficient, where the normalization range is [-1,1]. For different temperature offset situations, the threshold adjustment coefficient is used to characterize the sensitivity of the required adjustment system at this time.

[0079] Finally, after multiplying the preset rate threshold by the threshold adjustment coefficient, the sum of the product and the preset rate threshold is calculated as the adjustment creep rate threshold at that 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 implementer of the preset rate threshold adjusts it according to the specific implementation scenario and can be set to 0.005, which is not restricted here.

[0080] After adjusting the thresholds at different temperatures, the static load is adjusted based on the rate of change, reducing the extent to which the true load-bearing life assessment is obscured when the mechanical properties of the polyurethane composite material fluctuate drastically with temperature. Preferably, in an embodiment of the present invention, the method for obtaining the static load at the latter moment includes:

[0081] The rate of change of the load-bearing state value between each moment and the previous moment is calculated as the creep rate at each moment. The creep rate is characterized by the speed of the state change. In an embodiment of the present invention, the ratio of the difference between the load-bearing state value between each moment and the previous moment and the time length between the moments is used as the change rate, that is, the creep rate.

[0082] 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 the material may be at risk of direct fracture, so adjustment is required. The difference between the current creep rate and the adjusted creep rate threshold is calculated as the ratio of the adjusted creep rate threshold to the adjusted creep rate threshold. The higher the creep rate exceeds, the more load reduction is required.

[0083] Furthermore, the product of the negatively correlated mapping of the load state value at the corresponding moment and the adjustment ratio is used as the load adjustment coefficient at that moment. The worse the load state at that moment, the greater the degree of adjustment required to ensure a stable and complete test. Finally, 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. By reducing the load, the overall stability of the test is ensured, and a more realistic anti-creep condition of the pole can be evaluated.

[0084] In an embodiment of the present invention, the creep resistance index is obtained according to the static load change and the load state value at a certain moment, including:

[0085] At each moment, the difference in static load between one moment and the next is used as the adjustment amplitude at that moment. The load state at each moment is negatively correlated with the adjustment amplitude and multiplied by the normalized value to obtain the creep index at that moment. For polyurethane composite poles, the smaller the load amplitude required for adjustment and the better the load state, the greater the pole's deformation resistance, i.e., the higher the creep index.

[0086] S3: Based on the correlation between the load state value and 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 is adjusted by the fluctuation of the change rate of the current load state value to obtain the dynamic load frequency at the next moment; according to the load state value at each moment, as well as the distribution of the previous dynamic load amplitude and dynamic load frequency, the fatigue resistance index at the moment is obtained.

[0087] Fatigue testing of polyurethane composite poles is performed by dynamically varying load parameters, i.e., changing amplitude and frequency. This considers the effects of sustained wind gusts in the field, and assesses the pole's lifespan through repeated stress conditions. However, the fatigue testing process is still affected by temperature, and the load parameters during fatigue testing are also affected by the creep testing process. Creep testing causes the pole to slowly deform, leading to a gradual decrease in its fatigue resistance. When the creep rate is too high, the material's deformation in each fatigue cycle increases, potentially accumulating excessive deformation in a short period of time, accelerating fatigue crack propagation and causing the test results to favor a shorter fatigue life.

[0088] Since the increase in temperature will cause the elastic modulus of polyurethane to decrease, the deformation under the same load will increase, resulting in unrealistic accelerated damage. Therefore, the dynamic load parameters are reduced in combination with the load-bearing state of the pole at temperature, and the strain level of the pole during service is maintained for testing to improve the accuracy of subsequent life assessment.

[0089] In an embodiment of the present invention, a method for obtaining the dynamic load amplitude at a later moment includes:

[0090] First, for any moment, in the time sequence before that moment, a two-dimensional coordinate system is constructed based on the temperature and the load state value at that moment. The horizontal axis of the two-dimensional coordinate system 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, which reflects 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.

[0091] Load corrections are then made based on real-time changes and sensitivity coefficients. After calculating the temperature difference between the current moment and the previous one, the ratio of the temperature difference to the temperature at that moment is used as the temperature change. The product of the temperature change and the temperature sensitivity coefficient is used as the temperature adjustment coefficient. By analyzing the impact of real-time temperature changes on the load-bearing state, adjustments are made. The greater the temperature change, the more dramatic the change in material state, and the more significant the load adjustment required.

[0092] 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.

[0093] 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:

[0094] The difference between the creep rate at each moment and the historical average creep rate, and the ratio of this difference to the historical average creep rate, are used as the frequency adjustment coefficient for each moment. The historical average creep rate is the average of the creep rates at all moments preceding the moment. The greater the creep rate, the lower the fatigue test frequency. The dynamic load frequency at each moment is multiplied by the frequency adjustment coefficient, and the difference between the dynamic load frequency and the product is calculated as the dynamic load frequency at the next moment.

[0095] The fatigue resistance of the pole is reflected by combining the cumulative fatigue degree up to the current moment with the state index. Preferably, in an embodiment of the present invention, the method for obtaining the fatigue resistance index includes:

[0096] For any moment, the cumulative index of the moment is obtained by combining all the dynamic load amplitudes, dynamic load frequencies and test durations before the moment. In an embodiment of the present invention, the mean of all the dynamic load amplitudes before the moment is used as the average dynamic load amplitude. The larger the value, the stronger the material's ability to withstand high loads. The mean of all the dynamic load frequencies before the moment is used as the average dynamic load frequency. The larger the value, the better the resistance to high-frequency fatigue. The time from the moment to the start of the test is used as the test duration. The longer the duration, the better the life. 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 fatigue resistance.

[0097] 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. The larger the load-bearing state value, the lower the degree of damage. The anti-fatigue index is obtained by combining the cumulative index. The larger the anti-fatigue index, the better the fatigue performance.

[0098] S4: Determine the stopping time according to the size of the load-bearing state index; obtain the load-bearing capacity test results by analyzing the trend changes of the creep resistance index and fatigue resistance index before the stopping time, combined with the distribution of the load-bearing state value and the load deviation distribution under deformation.

[0099] When the cracks on the pole surface or the deformation of the pole reaches a certain extent, the test can be stopped, that is, the bearing capacity of the pole reaches its limit. At this time, the ultimate bearing capacity of the polyurethane composite pole is evaluated based on the data obtained during the test.

[0100] In an embodiment 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 its limit, the test is stopped, and this time is recorded as the stop moment, where the preset stop threshold is set to 0.3, and the specific value can be adjusted by the implementer.

[0101] According to the creep and fatigue indexes analyzed after the test was stopped, the load-bearing conditions of the pole were comprehensively considered from the perspective of service life, and the degree of load application after the pole was significantly deformed was further considered to reflect the sustainability of the pole to the limit, that is, to characterize the toughness of the pole. Therefore, the test results were obtained from the creep and fatigue indexes after the test, as well as the load deviation after deformation, combined with the overall load-bearing status value.

[0102] In an embodiment of the present invention, a linear fit is performed on the numerical distribution of the creep resistance index in the time series before the stop moment, and the fitting slope is negatively correlated to obtain a creep life assessment value. A linear fit is performed on the numerical distribution of the fatigue resistance index in the time series, and the fitting slope is negatively correlated to obtain a fatigue life assessment value. As the pole approaches its limit, the load-bearing condition will deteriorate, and the creep resistance index and fatigue resistance index will also decrease. The slope of the fitting of the values ​​in the continuous time series reflects the degree of trend. When the slope value is smaller, the exponential decay is slower, and the service life of the pole is longer.

[0103] Therefore, the creep life assessment value and the fatigue life assessment value are combined to obtain a life assessment index. In an embodiment of the present invention, the product of the creep life assessment value and the fatigue life assessment value is used as the life assessment index. The larger the life assessment index, the better the bearing capacity.

[0104] Then, the difference between the load at the beginning of deformation and the maximum load between the beginning and the end of deformation is negatively correlated to obtain the toughness evaluation index. The closer the load at the beginning of deformation is to the load at the end, the smaller the process from deformation to fracture limit of the material, the better the toughness of the pole, and the better the overall load-bearing condition.

[0105] Finally, by combining all the load-bearing state values, life evaluation indexes, and toughness evaluation indexes in the time series, a load-bearing capacity index is obtained as the load-bearing capacity test result. In an embodiment of the present invention, the mean of all the load-bearing state values ​​in the time series before the stop moment is taken as the average load-bearing state, reflecting the average load-bearing state of the entire test. The larger the average load-bearing state, the better the overall performance of the pole. Therefore, the product of the average load-bearing state, the life evaluation index, and the toughness evaluation index is normalized to obtain a load-bearing capacity index as the load-bearing capacity test result, integrating the three factors of life, toughness, and state. The larger the load-bearing capacity index, the better the comprehensive load-bearing capacity.

[0106] In an embodiment of the present invention, it can be subsequently determined whether the standards are met based on the bearing capacity test results, and whether the long-term service requirements are met can be determined by the size 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 and improvement direction are determined according to the damage state. For example, when brittle fracture occurs, that is, there is no plastic deformation at low temperature, it is necessary to optimize the material formula or add toughening agents. When toughness failure occurs, that is, large-scale deformation at high temperature, it is necessary to increase the matrix stiffness or reduce the service temperature. When fatigue crack propagation occurs, it is necessary to check the manufacturing process, such as checking the uniformity of the fiber layup or adding local reinforcement, etc.

[0107] In summary, the present invention utilizes the physical deformation characteristics of poles during temperature-dependent load-bearing capacity testing to simultaneously conduct static and dynamic load tests. This facilitates analysis of the long-term service life of poles from the perspectives of creep resistance and fatigue resistance, thereby providing a more comprehensive assessment of the pole's load-bearing capacity under complex conditions. First, the load-bearing state is characterized by deformation at any given moment. After adjusting the creep rate threshold based on the temperature change and the decrease in the real-time load-bearing state, the static load is adjusted based on the offset of the load-bearing state change rate at that moment. This considers the creep rate changes caused by temperature's impact on the material's internal activity, preventing overload from accelerating damage and affecting the load-bearing assessment. Combining the static load change and load-bearing state, a creep resistance index is derived. Furthermore, the temporal correlation between temperature and load-bearing state, as well as the dynamic load amplitude correction based on temperature changes at that moment, are considered. The dynamic load amplitude needs to be adjusted to accommodate the decrease in material modulus at high temperatures to adapt to actual operating conditions. Furthermore, the dynamic load frequency is adjusted based on the rate of change of the load-bearing state value, taking into account the fatigue reduction caused by creep analysis to adjust the fatigue resistance test rhythm. Finally, the fatigue resistance index is derived by combining the accumulated temporal state and the load-bearing state at that moment. After the real-time load-bearing state reaches its limit, the load-bearing test results are obtained by combining the creep and fatigue resistance trends during the test with the load state and the load changes that produce deformation. Taking into account the creep life and fatigue life, the toughness of the deformation load, and the load state, a more optimal load-bearing capacity test result is obtained. The present invention combines dynamic fatigue and creep testing with temperature changes, dynamically adjusting the load parameters according to the real-time temperature and real-time pole state during the test process, more comprehensively testing the load capacity of the pole under different environments and obtaining more accurate pole load-bearing capacity test results.

[0108] It should be noted that the order in which the embodiments of the present invention are described above is for illustrative purposes only and does not necessarily represent the superiority or inferiority of the embodiments. The processes depicted in the accompanying drawings do not necessarily require the specific order or sequential order shown to achieve the desired results. In certain embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0109] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various 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 comprises: In the variable temperature bearing capacity test, the temperature, deformation parameters, static load, dynamic load amplitude and dynamic load frequency of the pole at each moment are obtained; based on the deformation parameters at each moment, the bearing state value at each moment is obtained; Adjust the creep rate threshold based on the temperature change and the degree of reduction in the load state value at that moment; analyze the offset of the load state value change rate based on the current adjusted creep rate threshold, and correct the static load in combination with the load state value to obtain the static load at the next moment; obtain the creep resistance index at each moment based on the static load change and the load state value at each moment; Based on the correlation between the load state value and temperature in the 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 is adjusted by the fluctuation of the change rate of the current load state value to obtain the dynamic load frequency at the next moment; based on the load state value at each moment, as well as the distribution of the previous dynamic load amplitude and dynamic load frequency, the fatigue resistance index at the moment is obtained; The stopping time is determined according to the load state index; the load capacity test results are obtained by combining the trend changes of the creep resistance index and fatigue resistance index before the stopping time with the distribution of the load state value and the load deviation distribution under deformation; The method for obtaining the bearer status includes: The deformation parameters include the crack area, the strain values ​​at all positions on the pole, and the support plate displacement; For any moment, the variance of the strain values ​​at all positions at that moment is negatively correlated and normalized to obtain the strain bearing capacity; the support plate displacement at that moment is negatively correlated and normalized to obtain the displacement bearing capacity; the strain bearing capacity and the displacement bearing capacity at that moment are weighted summed to obtain the deformation bearing capacity at that moment; The product of the negative correlation mapping value of the crack area at that moment and the deformation bearing capacity is normalized to obtain the bearing state value at that moment.

2. The method for testing the bearing capacity of a polyurethane composite material pole according to claim 1, characterized in that: The step of adjusting the creep rate threshold according to the temperature change at a given moment and the degree of reduction in the load state value includes: For any moment, the difference between the temperature at that moment and the previous average temperature is taken as the temperature offset at that moment; Within the preset pre-order range at that moment, the average rate of reduction of the load status indicator is calculated and negative correlation mapping is performed to obtain the reduction adjustment degree; The threshold adjustment coefficient at that moment is obtained by combining the temperature offset and the reduction adjustment degree; after multiplying the preset rate threshold by the threshold adjustment coefficient, the sum of the product and the preset rate threshold is calculated as the adjustment creep rate threshold at that moment.

3. The method for testing the bearing capacity of a polyurethane composite pole according to claim 1, characterized in that: The method for obtaining the static load at the next moment includes: Calculate the rate of change of the load 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 difference between the creep rate and the adjusted creep rate threshold and the ratio of the adjusted creep rate threshold are used as the adjustment ratio; the product of the value of the negative correlation mapping of the load 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.

4. The method for testing the bearing capacity of a polyurethane composite pole according to claim 1, characterized in that: The method for obtaining the creep resistance index includes: For each moment, the difference in static load between each moment and the next moment is taken as the adjustment amplitude at each moment; The anti-creep index at each moment is obtained by multiplying the value of the negative correlation mapping between the load state and the adjustment amplitude at each moment.

5. The method for testing the bearing capacity of a polyurethane composite pole according to claim 1, characterized in that: The method for obtaining the dynamic load amplitude at the next moment includes: For any moment, a two-dimensional coordinate system is constructed based on the temperature and load state value at that moment in the time series before that moment. The horizontal axis of the two-dimensional coordinate system is the temperature, and the vertical axis is the load state value. Each moment is mapped to the two-dimensional coordinate system and a straight line is fitted. The slope of the fitted line is used as the temperature sensitivity coefficient. After calculating the temperature difference between the current moment and the previous moment, the ratio of the temperature difference to the temperature at that moment is taken as the temperature change degree; the product of the temperature change degree and the temperature sensitivity coefficient is taken 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 the current moment and the product is calculated as the dynamic load amplitude at the next moment.

6. The method for testing the bearing capacity of a polyurethane composite pole according to claim 3, characterized in that: 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 difference to the historical average creep rate are 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.

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

8. The method for testing the bearing capacity of a polyurethane composite pole according to claim 1, characterized in that: The method for obtaining the bearing capacity test result includes: In the time series before the stop moment, a linear fit is performed on the numerical distribution of the creep resistance index in the time series, and the fitting slope is negatively correlated to obtain the creep life evaluation value; a linear fit is performed on the numerical distribution of the fatigue resistance index in the time series, and the fitting slope is negatively correlated to obtain the fatigue life evaluation value; Combining creep life assessment value and fatigue life assessment value to obtain life assessment index; The difference between the load at the start of deformation and the maximum load between the start and stop of deformation is negatively correlated to obtain the toughness evaluation index; Combining all the load-bearing state values, life evaluation indicators and toughness evaluation indicators in the time series, the load-bearing capacity index is obtained as the load-bearing capacity test result.

9. A bearing capacity testing device for polyurethane composite poles, characterized in that: It includes a temperature control module and a variable temperature test module, wherein the temperature control module is used to control temperature changes; the variable temperature test module includes an acquisition unit, an analysis and control unit, and a test evaluation unit; The signal output end of the acquisition unit is connected to the signal input end of the analysis control unit, and the signal output end of the analysis control unit is connected to the signal input end of the test evaluation unit. The analysis control unit is used for data analysis and regulating subsequent loads; the test evaluation unit is used for evaluating test results; The acquisition unit acquires 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 control unit; The analysis control unit obtains the load-bearing state value at each moment according to each deformation parameter at each moment; Adjusting the creep rate threshold according to the temperature change at the time and the degree of reduction of the load state value; Analyze the offset of the load state value change rate based on the current creep rate threshold, and correct the static load based on the load state value to obtain the static load at the next moment; According to the static load change and load state value at each moment, the creep resistance index at that moment is obtained; The method for obtaining the bearer status includes: The deformation parameters include the crack area, the strain values ​​at all positions on the pole, and the support plate displacement; For any moment, the variance of the strain values ​​at all positions at that moment is negatively correlated and normalized to obtain the strain bearing capacity; the support plate displacement at that moment is negatively correlated and normalized to obtain the displacement bearing capacity; the strain bearing capacity and the displacement bearing capacity at that moment are weighted summed to obtain the deformation bearing capacity at that moment; Normalize the product of the negative correlation mapping value of the crack area at that moment and the deformation bearing capacity to obtain the bearing state value at that moment; Based on the correlation between the load state value and temperature in the 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 is adjusted by the fluctuation of the change rate of the current load state value to obtain the dynamic load frequency at the next moment; based on the load state value at each moment, as well as the distribution of the previous dynamic load amplitude and dynamic load frequency, the fatigue resistance index at the moment is obtained; Determine the stopping time according to the size of the load status indicator; transmit the analysis data before the stopping time to the test evaluation unit; The test evaluation unit obtains the bearing capacity test results by combining the trend changes of the creep resistance index and fatigue resistance index before the stopping moment with the distribution of the bearing state value and the load deviation distribution under deformation.

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