An outdoor LED display screen predictive maintenance method and system

Abstract

The application provides an outdoor LED display screen predictive maintenance method and system, and relates to the technical field of display screen maintenance, wherein the method comprises the following steps: determining a plurality of temperature rise and fall periods of an environment in which an outdoor LED display screen is located; calculating, for a temperature fluctuation difference and a maximum temperature value corresponding to each temperature rise and fall period, a cycle cycle number required for each solder joint to reach solder joint failure; determining an included angle between a direction and a direct sunlight direction, and combining a distance between each solder joint and a center point of a printed circuit board to calculate a stress amplification coefficient of each solder joint; calculating cumulative damage values of a plurality of solder joints according to the stress amplification coefficient of each solder joint and the corresponding cycle cycle number; predicting a corresponding failure time according to the cumulative damage value of a failure solder joint, and generating a maintenance instruction according to the position of the failure solder joint and the failure time. The application can accurately predict failure to the solder joint level, thereby improving the accuracy of maintenance.

Description

Technical Field

[0001] This application relates to the field of display screen maintenance technology, and in particular to a predictive maintenance method and system for outdoor LED displays. Background Technology

[0002] Outdoor light-emitting diode (LED) displays are exposed to the natural environment for extended periods, enduring alternating effects from diurnal temperature variations, high-temperature exposure, and low-temperature freeze-thaw cycles. Among their various failure modes, solder joint fatigue failure is a typical one. Due to the difference in thermal expansion coefficients between the LED chip and the printed circuit board, the solder joint is subjected to cyclic thermomechanical stress during each temperature cycle, gradually accumulating fatigue damage. When the fatigue damage accumulates to a certain extent, cracks will initiate and propagate at the solder joint, eventually leading to LED chip failure.

[0003] Currently, there are two main ways to operate and maintain LED displays. One is through regular inspections and post-incident repairs, which is delayed and cannot intervene within the window of time before a fault occurs. The other is fault diagnosis based on condition monitoring, which identifies anomalies in the current operating status by collecting parameters such as current, voltage, and brightness of the display in real time. Although this method can identify anomalies that have already occurred, its accuracy in estimating the time of fault occurrence is limited.

[0004] In recent years, some technical solutions have attempted to combine data analysis with predictive maintenance, but when applied to outdoor LED display scenarios, the following problems exist: insufficient attention is paid to the impact of factors such as temperature cycling and direct sunlight on the long-term cumulative fatigue of solder joints in outdoor environments, resulting in discrepancies between fault prediction results and actual degradation processes; the granularity of processing the differences in environmental loads borne by solder joints at different locations is too coarse, making it difficult to provide prediction results accurate to the specific solder joint level; and the description of the nonlinear characteristics of accelerated growth in the late stage of solder joint damage is not refined enough, resulting in a certain gap between the fault time estimation and the actual evolution law. Summary of the Invention

[0005] This application provides a predictive maintenance method and system for outdoor LED displays, which addresses the problems of insufficient accuracy in predicting solder joint-level faults, coarse granularity in handling differences in the spatial distribution of solder joints, and insufficient fineness in describing the nonlinear characteristics of late-stage damage in existing solutions for outdoor LED display scenarios.

[0006] To address the aforementioned technical problems, in a first aspect, this application provides a predictive maintenance method for outdoor LED displays, comprising: Determine multiple temperature rise and fall cycles of the environment where the outdoor LED display screen is located; For each temperature rise and fall cycle, calculate the number of cycles required for each solder joint on the outdoor LED display to fail, based on the temperature fluctuation difference and the highest temperature value. Determine the angle between the orientation of the outdoor LED display screen and the direction of direct sunlight, and calculate the stress amplification factor of each solder joint based on the distance between each solder joint and the center point of the printed circuit board. The cumulative damage value of multiple solder joints is calculated based on the stress amplification factor of each solder joint and the number of cycle times corresponding to multiple temperature rise and fall cycles. Based on the cumulative damage values ​​of multiple solder joints, the faulty solder joint is identified, and the corresponding failure time is predicted based on the cumulative damage value of the faulty solder joint. Based on the location of the faulty solder joint and the failure time, maintenance instructions for the outdoor LED display screen are generated.

[0007] Optionally, determine the angle between the orientation of the outdoor LED display and the direction of direct sunlight, and calculate the stress amplification factor for each solder joint based on the distance between each solder joint and the center point of the printed circuit board, including: Obtain the coordinates of the solder joint on the printed circuit board, calculate the distance from the solder joint to the center of the printed circuit board based on the coordinates, and use the distance as the position distance factor of the solder joint; Obtain the installation location and orientation information of the outdoor LED display screen, determine the direct sunlight direction based on the installation location and current time, determine the orientation angle of the outdoor LED display screen based on the orientation information, calculate the angle between the orientation angle and the direct sunlight direction, and take the larger value between the cosine of the angle and zero as the solar incidence factor of the solder joint. The stress amplification factor of the weld joint is obtained by weighting and summing the distance factor and the solar radiation factor according to the preset weights.

[0008] Optionally, based on the stress amplification factor of each solder joint and the number of cycle times corresponding to multiple temperature rise and fall cycles, the cumulative damage value of multiple solder joints is calculated, including: For each solder joint and each temperature rise / fall cycle, the stress amplification factor of the solder joint is multiplied by the reciprocal of the number of cycles corresponding to the temperature rise / fall cycle to obtain the single damage increase of the solder joint caused by the temperature rise / fall cycle. For each solder joint, the increase in damage caused by each single temperature rise and fall cycle is accumulated to obtain the cumulative damage value of the solder joint.

[0009] Optionally, predicting the corresponding failure time based on the cumulative damage value of the faulty solder joint includes: Construct a power-law relationship between the damage growth rate of the faulty solder joint and the damage value of the faulty solder joint. The power-law relationship includes the damage growth rate coefficient and the damage acceleration index. Using the cumulative damage value of the faulty solder joint as the initial condition, the power relation is integrated to obtain an analytical expression for the change of the damage value of the faulty solder joint over time. Based on the analytical expression, the time corresponding to when the damage value of the faulty solder joint reaches the preset damage threshold is calculated, and the time is determined as the fault time of the faulty solder joint.

[0010] Optionally, multiple temperature rise and fall cycles of the environment where the outdoor LED display is located can be determined, including: The temperature time series of outdoor LED displays within a preset period is obtained through the Industrial Internet; The temperature time series was processed using the rainflow counting method to extract multiple temperature rise and fall cycles from the temperature time series, and the temperature fluctuation difference and the highest temperature value corresponding to each temperature rise and fall cycle were obtained.

[0011] Optionally, for each temperature rise / fall cycle corresponding to the temperature fluctuation difference and the highest temperature value, calculate the number of cycle cycles required for each solder joint on the outdoor LED display to reach solder joint failure, including: For each solder joint and each temperature rise / fall cycle on the outdoor LED display screen, the temperature fluctuation difference and the highest temperature value corresponding to the temperature rise / fall cycle are substituted into the preset solder joint fatigue life model to calculate the number of cycle cycles required for the solder joint to fail under the working conditions corresponding to the temperature rise / fall cycle.

[0012] Optionally, the faulty solder joints are identified based on the cumulative damage values ​​of multiple solder joints, including: Compare the cumulative damage values ​​of all solder joints on the outdoor LED display screen, and identify the solder joint with the highest cumulative damage value as the faulty solder joint.

[0013] Optionally, after identifying the faulty solder joint based on the cumulative damage values ​​of multiple solder joints, the method further includes: Obtain the location of historical faulty solder joints on outdoor LED displays; Determine whether the location of the historical faulty solder joint is within the same display cabinet as the location of the faulty solder joint. When the location of the historical fault solder joint and the location of the fault solder joint are located in the same display box, the damage growth rate coefficient is multiplied by the preset rate acceleration factor to obtain the accelerated damage growth rate coefficient, and the rate acceleration factor is greater than 1. Multiply the damage acceleration index by the preset acceleration factor to obtain the accelerated damage acceleration index, where the acceleration factor is greater than 1. The failure time of the faulty solder joint is re-predicted using the accelerated damage growth rate coefficient and the accelerated damage acceleration index.

[0014] Optionally, maintenance instructions for the outdoor LED display screen are generated based on the location of the faulty solder joint and the time of the fault, including: Based on the location of the faulty solder joint, determine the display cabinet number and printed circuit board number corresponding to the faulty solder joint on the outdoor LED display screen. Subtract the preset lead time from the downtime to obtain the execution time of the maintenance command; The display box number, printed circuit board number, location of the faulty solder joint, and execution time will be packaged into a maintenance instruction and sent to the maintenance terminal.

[0015] Secondly, this application provides a predictive maintenance system for outdoor LED displays, comprising: The determination module is used to determine multiple temperature rise and fall cycles of the environment where the outdoor LED display is located; The first calculation module is used to calculate the number of cycles required for each solder joint on the outdoor LED display to reach solder joint failure, based on the temperature fluctuation difference and the highest temperature value corresponding to each temperature rise and fall cycle. The second calculation module is used to determine the angle between the orientation of the outdoor LED display screen and the direction of direct sunlight, and to calculate the stress amplification factor of each solder joint in combination with the distance between each solder joint and the center point of the printed circuit board. The third calculation module is used to calculate the cumulative damage value of multiple solder joints based on the stress amplification factor of each solder joint and the number of cycle cycles corresponding to multiple temperature rise and fall cycles. The generation module is used to identify faulty solder joints based on the cumulative damage values ​​of multiple solder joints, predict the corresponding failure time based on the cumulative damage values ​​of the faulty solder joints, and generate maintenance instructions for the outdoor LED display screen based on the location and failure time of the faulty solder joints.

[0016] The technical solution provided in this application has the following beneficial effects: The outdoor ambient temperature time series is processed using the rainflow counting method to extract temperature rise and fall cycles. Combined with the solder joint fatigue life model, the number of cycle counts for each solder joint under each temperature rise and fall cycle is calculated. A stress amplification factor based on the angle of direct sunlight and the distance between the solder joint and the center of the printed circuit board is introduced to refine the cumulative damage calculation to the level of each solder joint, thus refining fault prediction from the module level to the solder joint level and improving the accuracy of maintenance. By constructing a power relationship between the damage growth rate and the damage value to extrapolate the fault time, the nonlinear characteristics of the accelerated growth of solder joint damage in the late stage can be reflected, improving the accuracy of fault time prediction. By integrating historical fault solder joint location data, the fault solder joints in the same display cabinet are predicted more quickly, improving the utilization of real operating data by the prediction model. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is an overall flowchart of a predictive maintenance method for an outdoor LED display screen disclosed in this application.

[0019] Figure 2 This is a schematic diagram of a temperature time series and rainflow counting method processing method disclosed in this application.

[0020] Figure 3 This is a schematic diagram illustrating the spatial distribution of solder joints on a printed circuit board and the calculation of stress amplification factor as disclosed in this application.

[0021] Figure 4 This is a schematic diagram of a nonlinear growth curve of damage value over time as disclosed in this application.

[0022] Figure 5 This is a schematic diagram of a historical fault data fusion and accelerated prediction process disclosed in this application. Detailed Implementation

[0023] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. The described embodiments are only some embodiments of this application, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0024] Outdoor LED displays are typically installed on the facades of urban buildings, traffic sign towers, stadium walls, and commercial plaza pillars—positions that are high or difficult to access directly. Once a solder joint failure occurs, the cost and difficulty of on-site troubleshooting and repair are far greater than for indoor displays. Therefore, predictive maintenance of outdoor LED displays, and the ability to anticipate the location and timing of faulty solder joints before a failure actually occurs, is of significant engineering value in reducing maintenance costs and ensuring the reliable operation of outdoor LED displays.

[0025] See Figure 1 As shown in the figure, this application discloses a predictive maintenance method for outdoor LED displays, the method comprising: S1: Determine multiple temperature rise and fall cycles of the environment where the outdoor LED display screen is located.

[0026] The purpose of this step is to extract the temperature rise and fall cycle that can characterize the cyclic thermomechanical load on the solder joint from the actual ambient temperature data of the outdoor LED display. Since the temperature change in the outdoor environment is characterized by irregular fluctuations, the temperature time series is not a simple sinusoidal periodic signal. Therefore, a special load cycle extraction method is needed to process the temperature time series in order to accurately identify the complete temperature cycle contained in the temperature time series.

[0027] See Figure 2 As shown, the specific implementation process of step S1 includes steps S11 and S12.

[0028] S11: Obtain the temperature time series of the outdoor LED display screen within a preset period through the Industrial Internet.

[0029] The temperature time series refers to a sequence of temperature values ​​obtained by sampling the internal temperature of the outdoor LED display cabinet at fixed time intervals within a preset period. The preset period is used to limit the time range of temperature data collection, and can be set according to actual needs. For example, the preset period can be set to 90 days, and the fixed time interval for sampling can be set to 15 minutes.

[0030] The temperature time series contains all sampled temperature values ​​within a preset period. The sampled temperature values ​​are obtained from temperature sensors installed inside the outdoor LED display cabinet. The temperature sensors upload the collected temperature data to the data management platform via the Industrial Internet. The data management platform stores the received temperature data in chronological order to form a temperature time series.

[0031] S12: The temperature time series is processed using the rainflow counting method to extract multiple temperature rise and fall cycles from the temperature time series, and to obtain the temperature fluctuation difference and the highest temperature value corresponding to each temperature rise and fall cycle.

[0032] Among them, the rainflow counting method is a commonly used load cycle extraction method in the field of fatigue analysis. Since the rainflow counting method is a commonly used algorithm, this application will not elaborate on the basic principle of the rainflow counting method. The core idea of ​​the rainflow counting method is to pair the local peaks and local valleys in the temperature time series to identify the complete heating-cooling cycle or cooling-heating cycle. Each complete pairing constitutes a temperature rise and fall cycle.

[0033] The temperature rise / fall cycle is used to describe a complete temperature cycle process. Each temperature rise / fall cycle contains two characteristic parameters: temperature fluctuation difference and maximum temperature value. Temperature fluctuation difference refers to the difference between the temperature peak and the temperature trough in a temperature rise / fall cycle. Temperature fluctuation difference reflects the temperature change range that the solder joint experiences in the cycle. Maximum temperature value refers to the highest temperature that occurs in the temperature rise / fall cycle. Maximum temperature value reflects the highest temperature level that the solder joint is at in the cycle.

[0034] In practical engineering applications, assuming an outdoor LED display screen has 180 temperature rise and fall cycles extracted within a preset period of 90 days using the rain flow counting method, Table 1 below lists the characteristic parameters of the first 5 temperature rise and fall cycles: Table 1. Characteristic parameters of the first 5 temperature rise and fall cycles

[0035] As can be seen from Table 1 above, the temperature fluctuation difference and the highest temperature value are different in different temperature rise and fall cycles. The temperature fluctuation difference ranges from 15 degrees Celsius to 30 degrees Celsius, and the highest temperature value ranges from 318.15 Kelvin to 333.15 Kelvin. This difference reflects the temperature fluctuation characteristics of different time periods and seasons in the outdoor environment.

[0036] This application processes outdoor ambient temperature time series using the rainflow counting method, which can accurately extract complete temperature cycles and their characteristic parameters from irregularly fluctuating temperature data. This provides accurate load input for subsequent calculation of the number of cycle times of the weld joint based on the weld joint fatigue life model, avoiding fatigue life calculation deviations caused by inaccurate temperature cycle identification.

[0037] S2: For each temperature rise and fall cycle, calculate the number of cycles required for each solder joint on the outdoor LED display to reach solder joint failure, based on the temperature fluctuation difference and the highest temperature value.

[0038] In step S1, multiple temperature rise and fall cycles, as well as the temperature fluctuation difference and maximum temperature value corresponding to each temperature rise and fall cycle, have been extracted from the temperature time series. Since the temperature fluctuation difference and maximum temperature value are different for different temperature rise and fall cycles, the fatigue life of the solder joint also varies under different temperature rise and fall cycles. Therefore, this step needs to calculate the number of cycles required for the solder joint to reach solder joint failure under the working condition for each temperature rise and fall cycle, so that the damage contribution of each temperature rise and fall cycle can be accumulated in the subsequent step S4.

[0039] Solder joint fatigue life model 60 accepts two input parameters: temperature fluctuation difference. and the highest temperature value The solder joint fatigue life model 60 internally contains a power function term 61 and an Arrhenius term 62. The power function term 61 affects the temperature fluctuation difference. Processing was performed on Arrhenius term 62, which corresponds to the highest temperature value. After processing, the product of the two items is adjusted by coefficient A, and the number of cycle iterations is output. .

[0040] The specific implementation process of step S2 is as follows: First, for each solder joint and each temperature rise and fall cycle on the outdoor LED display screen, the temperature fluctuation difference and the highest temperature value corresponding to the temperature rise and fall cycle are substituted into the preset solder joint fatigue life model to calculate the number of cycle cycles required for the solder joint to fail under the working conditions corresponding to the temperature rise and fall cycle.

[0041] The construction process of the solder joint fatigue life model is as follows: First, solder joint samples of the same batch as the solder material actually used in outdoor LED displays are selected. Multiple sets of temperature cycle loads with different temperature fluctuation differences and different maximum temperature values ​​are applied to the solder joint samples on the accelerated life test bench. Multiple repeated samples are set under each working condition. The number of cycles experienced by each solder joint sample when it reaches failure is recorded to obtain multiple sets of experimental data. Then, according to the physical law that the thermomechanical damage of the solder joint during the temperature cycle is mainly controlled by the temperature fluctuation difference and the maximum temperature value, the product form of the modified Coffin-Manson model and the Arrhenius temperature acceleration factor is selected as the model structure. Finally, the least squares method is used to perform regression fitting on the experimental data. By minimizing the sum of squared residuals between the experimental measured values ​​and the model predicted values, the values ​​of each parameter in the solder joint fatigue life model are determined. The expression corresponding to the solder joint fatigue life model is shown in Equation (1).

[0042]

[0043] In equation (1), The number of cycles. This indicates the number of complete temperature cycles required for a solder joint to fail under the corresponding operating conditions during a given temperature rise and fall cycle. It is a dimensionless positive integer; This represents the temperature fluctuation difference, expressed in degrees Celsius. is the maximum temperature value, in Kelvin; A is the preset fatigue coefficient, a dimensional comprehensive coefficient. The dimension of A is determined by experimental fitting to ensure that the dimensions of both sides of the equation are consistent. Specifically, it can be set according to the accelerated life test data of the solder joint material. For example, for conventional lead-free solder, A can be set to 2942; m is the preset fatigue index, a dimensionless parameter. m reflects the sensitivity of temperature fluctuation difference to fatigue life. Specifically, it can be obtained by fitting the fatigue test data of the solder joint material. For example, m can be set to 2.65. The preset activation energy, The activation energy barrier used to describe the creep and diffusion process of solder joint materials at high temperatures is measured in electron volts, for example... It can be set to 0.122 electron volts; k is the Boltzmann constant, and the value of k is... Electron volts per Kelvin.

[0044] In the above fatigue life model for weld joints, the dimensional consistency of the formulas needs to be explained: exponential function middle, The unit of is electron volt, and the unit of k is electron volt per Kelvin. The unit is Kelvin, therefore The dimension of electron volts divided by electron volts is a dimensionless quantity, which satisfies the mathematical requirement that the independent variable of an exponential function must be dimensionless; the power function term middle, The unit is degrees Celsius, and m is a dimensionless parameter. The dimension of is -m degrees Celsius. This dimension cancels out the dimension of the coefficient A, making the entire right-hand side of the equation equal to the dimensionless periodic number of cycles on the left-hand side. Maintain consistency in dimensions.

[0045] To illustrate the calculation process for cumulative damage, we will take a solder joint as an example and assume that it reaches the required number of cycles to fail within the first 5 temperature rise and fall cycles. The following table shows the temperature rise and fall cycles corresponding to larger temperature fluctuations and higher maximum temperatures. (Smaller values), the following values ​​are for illustrative purposes only:

[0046] This can be understood as follows: the larger the temperature fluctuation difference and the higher the maximum temperature value, the smaller the corresponding cycle number, indicating a shorter fatigue life of the solder joint under that condition; conversely, the smaller the temperature fluctuation difference and the lower the maximum temperature value, the larger the corresponding cycle number, indicating a longer fatigue life of the solder joint under that condition.

[0047] This application transforms the temperature parameters of each temperature rise and fall cycle into the fatigue life of the solder joint under the working condition through a solder joint fatigue life model. This allows the damage effects of temperature cycles of different severity to the solder joint to be quantified and distinguished, providing a life benchmark for subsequent calculation of the cumulative damage value of the solder joint based on the Miner linear cumulative damage criterion.

[0048] S3: Determine the angle between the orientation of the outdoor LED display screen and the direction of direct sunlight, and calculate the stress amplification factor of each solder joint in combination with the distance between each solder joint and the center point of the printed circuit board.

[0049] In step S2, the number of cycles for each solder joint under each temperature rise and fall cycle has been calculated. This number of cycles reflects the theoretical fatigue life of the solder joint material under a uniform temperature field. However, in actual outdoor environments, the thermomechanical loads borne by solder joints at different locations of outdoor LED displays are not uniformly distributed. Due to the angle between the direction of direct sunlight and the orientation of the outdoor LED display, the solar radiation intensity received by the screen on the side facing the sun is greater than that on the side facing away from the sun, resulting in differences in the actual temperature field of solder joints at different locations. Meanwhile, the solder joints at the edge of the printed circuit board are more concentrated due to thermal expansion mismatch stress, and the solder joints farther away from the center of the printed circuit board bear greater thermomechanical stress. Based on the above two factors, this step introduces a stress amplification factor to correct the cumulative damage calculation of each solder joint, so that the prediction results can reflect the environmental load differences of the specific location of the solder joint on the outdoor LED display.

[0050] See Figure 3 As shown, the specific implementation process of step S3 includes steps S31 to S33.

[0051] Figure 3 In the diagram, printed circuit board 10 is a rectangular area, center point 20 is the geometric center of printed circuit board 10, solder joint 30 is the target solder joint for which the stress amplification factor is to be calculated, d is the normalized distance of solder joint 30 from center point 20, direct sunlight direction 40 is the incident direction of sunlight, and display screen orientation 50 is the normal direction of the outdoor LED display screen surface. The angle between the display screen facing 50° and the direction of direct sunlight 40°.

[0052] S31: Obtain the coordinates of the solder joint on the printed circuit board, calculate the distance from the solder joint to the center of the printed circuit board based on the coordinates, and use the distance as the position distance factor of the solder joint.

[0053] The positional distance factor is used to quantify the relative position of the solder joint on the printed circuit board. The farther the solder joint is from the center of the printed circuit board, the larger the positional distance factor, indicating that the thermal expansion mismatch stress borne by the solder joint is more concentrated. The coordinates of the solder joint on the printed circuit board can be obtained from the design data or manufacturing data of the outdoor LED display screen. Each solder joint corresponds to a set of planar coordinate values. The coordinates of the center of the printed circuit board are the positions corresponding to half of the length direction and half of the width direction of the printed circuit board. The distance of the solder joint from the center of the printed circuit board is calculated using the Euclidean distance formula. Then, this distance is divided by half of the diagonal length of the printed circuit board and normalized to obtain a dimensionless normalized distance with a value range of 0 to 1. This normalized distance is used as the positional distance factor of the solder joint.

[0054] S32: Obtain the installation location and orientation information of the outdoor LED display screen, determine the direct sunlight direction based on the installation location and current time, determine the orientation angle of the outdoor LED display screen based on the orientation information, calculate the angle between the orientation angle and the direct sunlight direction, and use the larger value between the cosine of the angle and zero as the solar incidence factor of the solder joint.

[0055] Among them, the solar incidence factor is used to quantify the intensity of solar radiation received by the outdoor LED display screen. The orientation angle of the outdoor LED display screen can be obtained from the installation engineering data. The direct direction of sunlight can be calculated by the solar position algorithm based on the latitude and longitude of the location of the outdoor LED display screen and the date and time. The included angle is the angle difference between the orientation angle of the outdoor LED display screen and the direct direction of sunlight. In the application scenario where the outdoor LED display screen faces the sun, the included angle ranges from 0 degrees to 90 degrees. The output of the cosine function within this range is a dimensionless quantity from 0 to 1. The smaller the included angle, the larger the cosine value and the larger the solar incidence factor, indicating that the outdoor LED display screen receives stronger solar radiation.

[0056] S33: The stress amplification factor of the weld joint is obtained by weighting and summing the position distance factor and the solar radiation factor according to the preset weights.

[0057] The stress amplification factor is used to amplify and correct the cumulative damage calculation of the solder joints. It reflects the environmental load differences at the specific locations of the solder joints on the outdoor LED display screen. Preset weights control the contribution ratios of the location distance factor and the solar radiation incident factor to the stress amplification factor. Specifically, the stress amplification factor is determined using multiple linear regression, based on the ratio of the strain amplitude to the strain amplitude under a uniform temperature field, obtained through finite element simulation analysis of the thermomechanical strain of solder joints at different locations under the combined effects of temperature cycling and solar radiation. and When simulation data is lacking, one can take... , As a default value, the expression for calculating the stress amplification factor is shown in equation (2).

[0058]

[0059] In equation (2): K is the stress amplification factor, which is a dimensionless quantity; d is the position distance factor of the weld point, which is a dimensionless quantity and ranges from 0 to 1. The solar incidence factor of the solder joint. It is a dimensionless quantity, with a value range from 0 to 1; The angle between the orientation of the outdoor LED display screen and the direction of direct sunlight; The weights of the location distance factor, The weights of the solar radiation incident factor, and All are dimensionless quantities and and The sum is 1, because d, , , Since both are dimensionless quantities, the stress amplification factor K obtained by weighted summation is also dimensionless, and the dimensional consistency of the addition operation is valid.

[0060] In practical engineering applications, assuming a printed circuit board is 200 mm long and 150 mm wide, and its diagonal length is... The printed circuit board (PCB) has a diagonal length of 125 mm. A solder joint is located 145 mm horizontally and 135 mm vertically from the bottom left corner of the PCB. The center of the PCB is located 100 mm horizontally and 75 mm vertically. The distance from the solder joint to the center of the PCB is... The location distance factor d = 75 / 125 = 0.6; assuming the angle between the orientation of the outdoor LED display screen and the direction of direct sunlight... satisfy =0.6, that is, the solar radiation incident factor is 0.6; Substituting the above value into equation (2), we get K=0.4×0.6+0.6×0.6=0.24+0.36=0.6.

[0061] This application introduces a stress amplification factor to quantify the spatial position difference and solar radiation direction difference of solder joints on outdoor LED displays into a dimensionless correction factor, enabling subsequent cumulative damage calculations to distinguish the environmental load differences of solder joints at different locations. This allows for fault prediction to be accurate down to the solder joint level, solving the problem of coarse-grained processing of spatial distribution differences of solder joints in existing solutions.

[0062] S4: Calculate the cumulative damage value of multiple solder joints based on the stress amplification factor of each solder joint and the number of cycle times corresponding to multiple temperature rise and fall cycles.

[0063] In step S2, the number of cycles for each solder joint under each temperature rise and fall cycle has been calculated. In step S3, the stress amplification factor for each solder joint has been calculated. Since the outdoor LED display screen has experienced multiple temperature rise and fall cycles within the preset period, each temperature rise and fall cycle causes a certain degree of fatigue damage to the solder joint. Therefore, this step needs to accumulate the damage caused to the solder joint by each temperature rise and fall cycle to obtain the cumulative damage value of the solder joint within the preset period.

[0064] The specific implementation process of step S4 includes steps S41 and S42; The calculation method in step S4 is based on the Miner linear cumulative damage criterion, which is a commonly used damage accumulation method in the field of fatigue analysis. Since the Miner linear cumulative damage criterion is a common method, this application will not elaborate on the basic principle of the Miner linear cumulative damage criterion. The core idea of ​​the Miner linear cumulative damage criterion is that the damage contribution of the solder joint after each complete temperature cycle under a certain temperature rise and fall cycle is equal to the reciprocal of the number of cycles under that condition. The damage contribution of each temperature rise and fall cycle can be linearly accumulated. When the accumulated damage value reaches 1, the solder joint reaches the failure state.

[0065] S41: For each solder joint and each temperature rise / fall cycle, multiply the stress amplification factor of the solder joint by the reciprocal of the number of cycles corresponding to the temperature rise / fall cycle to obtain the single damage increase value of the solder joint caused by the temperature rise / fall cycle.

[0066] The single-cycle damage increase is used to quantify the fatigue damage contribution of a single temperature rise / fall cycle to the solder joint. In the standard Miner linear cumulative damage criterion, the damage contribution of the solder joint undergoing one cycle under a certain temperature rise / fall cycle is the reciprocal of the number of cycles under that condition (1 / 2). This application introduces a stress amplification factor K as a correction factor to correct the single-damage contribution to K / ; The physical meaning of introducing the stress amplification factor is: Solder joints at different locations on an outdoor LED display screen experience different thermomechanical loads due to their spatial location and degree of solar radiation exposure. Solder joints located at the edge of the printed circuit board facing the sun have a larger stress amplification factor, while those located in the center facing away from the sun have a smaller stress amplification factor. This is achieved by adjusting the contribution of a single damage event to 1 / ... (the rest of the text is incomplete and requires further context for accurate translation). Corrected to K / This causes the weld joint with a larger stress amplification factor to accumulate more damage under the same temperature rise and fall cycle, thus reflecting the difference in environmental load borne by weld joints at different locations in the cumulative damage calculation. The calculation expression for the increase in damage value per instance is shown in equation (3).

[0067]

[0068] In equation (3), For the first The solder joint at the first The increase in damage per cycle corresponding to each temperature rise and fall period. It is a dimensionless quantity; For the first Stress amplification factor of each solder joint It is a dimensionless quantity; For the first Each temperature rise / fall cycle corresponds to the number of cycle cycles required to reach solder joint failure under operating conditions. Under the assumption of a uniform temperature field, this value is the same for all solder joints on the same display screen. It is a dimensionless positive integer; because and All of them are dimensionless quantities, therefore / The obtained single damage increase value It is also a dimensionless quantity.

[0069] S42: For each solder joint, the increase in damage caused by each single temperature rise and fall cycle is accumulated to obtain the cumulative damage value of the solder joint.

[0070] Among them, the cumulative damage value is used to characterize the total fatigue damage accumulated by the solder joint since the outdoor LED display screen was installed and put into operation. The cumulative damage value ranges from 0 to 1. When the cumulative damage value reaches 1, it indicates that the solder joint has reached the failure state. The calculation expression of the cumulative damage value is shown in equation (4).

[0071]

[0072] In equation (4): For the first The cumulative damage value of each solder joint The value is dimensionless; M represents the total number of temperature rise and fall cycles. It should be noted that when the outdoor LED display screen has run for multiple preset cycles, the cumulative damage value... It should include the cumulative damage contribution of all temperature rise and fall cycles within all preset cycles since installation and operation, rather than being limited to the cumulative result within the most recent preset cycle.

[0073] In practical engineering applications, taking the weld joint with a stress amplification factor K of 0.6 in the above embodiment as an example, and substituting it into equation (3) for numerical calculation, the numerical calculation results of the single damage increase of this weld joint in the first 5 temperature rise and fall cycles are shown in Table 3 below: Table 3. Individual damage increase and cumulative process during the first 5 temperature rise and fall cycles.

[0074] As shown in Table 3, the cumulative damage value of the solder joint in the first 5 temperature rise / fall cycles was 0.027. It should be noted that the first 5 temperature rise / fall cycles listed in Table 3 include relatively severe cycles such as high summer temperatures and large temperature differences, resulting in a relatively large increase in damage per cycle. In contrast, most temperature rise / fall cycles within the preset period are milder cycles with smaller temperature differences and lower maximum temperatures, corresponding to fewer cycle counts. The damage is relatively large, but the increase in damage per injury is relatively small. Therefore, the damage value obtained by accumulating all cycles cannot be proportionally extrapolated from the cumulative value of the first 5 cycles. In actual calculations, the damage values ​​of all cycles should be accumulated one by one. For example, the cumulative result of all cycles since the installation and operation of this solder joint is approximately 0.5. This value is an indicative cumulative damage level, indicating that the solder joint has consumed approximately 50% of its fatigue life.

[0075] This application uses the Miner linear cumulative damage criterion combined with the stress amplification factor to accumulate the damage contribution of each temperature rise and fall cycle to the solder joint, thereby realizing the quantitative assessment from single temperature cycle load to long-term cumulative fatigue damage, so that the fatigue damage state of each solder joint can be accurately tracked and quantified.

[0076] S5: Based on the cumulative damage value of multiple solder joints, identify the faulty solder joint, predict the corresponding failure time based on the cumulative damage value of the faulty solder joint, and generate maintenance instructions for the outdoor LED display screen based on the location and failure time of the faulty solder joint.

[0077] In step S4, the cumulative damage value of all solder joints on the outdoor LED display screen has been calculated. Since the larger the cumulative damage value, the closer the solder joint is to failure, this step first needs to determine the solder joint with the largest cumulative damage value as the faulty solder joint. Then, the failure time of the faulty solder joint is predicted based on the cumulative damage value of the faulty solder joint. Finally, the corresponding maintenance instruction is generated according to the location and failure time of the faulty solder joint. The specific implementation process of step S5 includes steps S51 to S54.

[0078] S51: Compare the cumulative damage values ​​of all solder joints on the outdoor LED display screen, and identify the solder joint with the highest cumulative damage value as the faulty solder joint. Since the solder joint with the highest cumulative damage value means that it has accumulated the most fatigue damage since installation and operation, it will be the first to reach the failure threshold under the same damage growth trend. Therefore, the solder joint with the highest cumulative damage value is identified as the faulty solder joint with the highest priority.

[0079] S52: Predict the corresponding failure time based on the cumulative damage value of the faulty solder joint.

[0080] See Figure 4 As shown, step S52 requires constructing a power relationship between the damage growth rate of the faulty solder joint and the damage value of the faulty solder joint. The power relationship is solved by integrating the cumulative damage value of the faulty solder joint as the initial condition, and then the failure time corresponding to the faulty solder joint reaching the preset damage threshold is predicted.

[0081] Figure 4 In the diagram, the horizontal axis represents time t, and the vertical axis represents the damage value D. The current cumulative damage value of the faulty solder joint is shown. The horizontal dashed line 70 corresponds to the preset damage threshold of 1.0, and the curve 80 represents the damage value D changing with time t from the initial value. The trend of the damage value increasing to the preset damage threshold of 1.0 is shown by curve 80. The increase is slow when the damage value is small, and the growth rate increases sharply when the damage value approaches 1.0, exhibiting a non-linear accelerated growth characteristic. The vertical dashed line 90 marks the failure time. The corresponding position.

[0082] The reason for using a power-law relationship to model the relationship between the damage growth rate and the damage value is based on the following research and development basis: The fatigue damage of the weld joint does not accumulate at a constant rate. Instead, in the later stages of damage, as microcracks propagate and converge, the weld joint's load-bearing cross-section continuously decreases, the stress concentration effect intensifies, and the damage growth rate accelerates with increasing damage severity. The exponential term in the power-law relationship can characterize this positive feedback acceleration mechanism. When the damage acceleration exponent is greater than 1, the damage growth rate exhibits superlinear growth with increasing damage value, precisely reflecting the nonlinear characteristics of accelerated growth in the later stages of weld joint damage. If a linear extrapolation method is used, it would assume a constant damage growth rate, leading to a later predicted failure time. It should be noted that the cumulative damage value obtained in step S4 based on the Miner linear accumulation criterion represents the proportion of fatigue life already consumed by the weld joint under historical temperature cyclic loading, and is used as the initial damage value for damage evolution in step S52. The power-law relationship in step S52 describes the evolution of the damage value over time after the damage enters the late-stage accelerated propagation phase, based on this initial damage. Both characterize different stages of damage accumulation: the former is used to obtain the current damage level of the solder joint by accumulating the damage over multiple operating temperature cycles, while the latter is used to extrapolate the nonlinear accelerated growth of the later stages of damage above this damage level. Damage growth rate coefficient. and damage acceleration index That is, by fitting the damage-time data of the weld joint in the acceleration phase, the damage evolution rate of the weld joint under its temperature field and stress environment is implicitly included. Therefore, the extrapolation process of equations (5) to (7) no longer introduces the temperature fluctuation difference and stress amplification factor on a cycle-by-cycle basis.

[0083] The specific implementation process of step S52 includes the following three sub-steps: The first sub-step is to construct a power law relationship between the damage growth rate of the faulty solder joint and the damage value of the faulty solder joint. The power law relationship includes a damage growth rate coefficient and a damage acceleration index. The damage growth rate coefficient is used to control the baseline rate of damage growth, and the damage acceleration index is used to control the degree to which damage growth accelerates as the damage value increases. The expression of the power law relationship is shown in equation (5).

[0084]

[0085] In equation (5): As the damage growth rate, This represents the derivative of the damage value D with respect to time t; D is the current damage value, which is dimensionless; t is time, in days. This is the damage growth rate coefficient. The unit is the negative first power of days; The damage acceleration index, For a dimensionless quantity, when When the value is greater than 1, the damage growth rate accelerates with increasing damage value D; the left side of the equation... The dimension of is negative first power of , and the right side of the equation The unit is the negative first power of days. Since it is a dimensionless quantity, therefore The dimension of is negative first power of , and the dimensions of both sides of the equation are consistent.

[0086] Damage growth rate coefficient and damage acceleration index The value can be obtained by fitting fatigue test data of the solder joint material, or it can be calibrated based on historical operating data of similar outdoor LED displays, for example. Can be set to , It can be set to 2.

[0087] The second sub-step: Using the cumulative damage value of the faulty solder joint as the initial condition, integrate the power relation to obtain an analytical expression for the change of the damage value of the faulty solder joint over time. Specifically, the cumulative damage value of the faulty solder joint... As initial conditions, the power relation is separated into variables and solved by integration. When the value is not equal to 1, the analytical expression for the change of the damage value D with time t is shown in equation (6).

[0088]

[0089] In equation (6), This represents the current cumulative damage value of the faulty solder joint. This is derived from the total cumulative damage value of the solder joint since the outdoor LED display screen was installed and put into operation, calculated in step S4.

[0090] The third sub-step: Substitute D(t)=1.0 into the analytical expression and solve for time t to obtain the calculation expression for the fault time, as shown in equation (7).

[0091]

[0092] In equation (7), The fault time of the faulty solder joint is expressed in days; the preset damage threshold is 1.0, which can be set according to actual needs.

[0093] In practical engineering applications, continuing with the above embodiment, it is assumed that the weld joint has accumulated all its cumulative damage values ​​since installation and operation. =0.5, damage growth rate coefficient = Damage Acceleration Index =2, substitute the above value into equation (7); since =2, =1 / 0.5=2, therefore =(1 2)÷[(1 2)×0.005]=( 1)÷( 0.005) = 200 days, meaning the faulty solder joint is expected to reach failure status in about 200 days.

[0094] S53: Accelerate the correction of fault time of faulty solder joints by integrating historical fault data.

[0095] See Figure 5 As shown, after completing the fault time prediction in step S52, the prediction results can be further corrected by integrating historical fault data. The specific implementation process of step S53 is as follows: obtain the location of the historical fault solder joints of the outdoor LED display screen; determine whether the location of the historical fault solder joints and the location of the fault solder joints are located in the same display cabinet. When the location of the historical fault solder joints and the location of the fault solder joints are located in the same display cabinet, it indicates that the overall environmental conditions or manufacturing batch characteristics of the display cabinet may cause the degradation rate of the solder joints to be higher than the average level. Therefore, it is necessary to accelerate the correction of the predicted failure time.

[0096] The specific method for accelerating the correction is as follows: Multiply the damage growth rate coefficient by a preset rate acceleration factor to obtain the accelerated damage growth rate coefficient. The rate acceleration factor is greater than 1; for example, it can be set to 1.2. Multiply the damage acceleration index by a preset exponential acceleration factor to obtain the accelerated damage acceleration index. The exponential acceleration factor is greater than 1; for example, it can be set to 1.1. Then, substitute the accelerated damage growth rate coefficient and the accelerated damage acceleration index into the failure time calculation expression in step S52 to re-predict the failure time of the faulty solder joint. Specifically, the ratio of the average failure time of historical faulty solder joints within the same display enclosure to the average failure time of all solder joints is calculated, and the reciprocal of this ratio is taken as the rate acceleration factor. If historical faulty solder joints exhibit location clustering, the exponential acceleration factor can be set to a value between 1.1 and 1.3, specifically obtained by fitting from historical data through maximum likelihood estimation.

[0097] S54: Generate maintenance instructions for the outdoor LED display screen based on the location of the faulty solder joint and the time of the fault.

[0098] The specific implementation process of step S54 is as follows: First, based on the location of the faulty solder joint, determine the display cabinet number and printed circuit board number corresponding to the faulty solder joint on the outdoor LED display screen. The display cabinet number and printed circuit board number can be obtained by querying the installation ledger data of the outdoor LED display screen. Then, the failure time is subtracted from the preset lead time to obtain the execution time of the maintenance instruction; the preset lead time is used to reserve the preparation and implementation time required for maintenance work before the failure actually occurs, and can be set according to actual needs, for example, the preset lead time can be set to 30 days. Finally, the display case number, printed circuit board number, location of the faulty solder joint, and execution time will be packaged into a maintenance instruction and sent to the maintenance terminal.

[0099] In practical engineering applications, assuming the faulty solder joint is located on the second printed circuit board of the third display cabinet, and the fault time after accelerated correction in step S53 is approximately 180 days, with a preset lead time of 30 days, the execution time of the maintenance command is 180 days. After 30 = 150 days, the maintenance instruction will include the display box number 3, the printed circuit board number 2, the coordinates of the faulty solder joint on the printed circuit board, and the execution time of 150 days from the current time.

[0100] This application models the nonlinear acceleration relationship between the damage growth rate and the damage value using a power-law formula, which can capture the characteristics of accelerated growth in the late stage of solder joint damage, making the predicted failure time more accurate than the linear extrapolation method. By integrating historical failure data to accelerate the correction of faulty solder joints in the same display box, the prediction accuracy is further improved. By encapsulating the location of the faulty solder joint and the predicted failure time into maintenance instructions and sending them to the maintenance terminal, closed-loop management of predictive maintenance is realized.

[0101] This application also provides a predictive maintenance system for outdoor LED displays, the system comprising: The determination module is used to determine multiple temperature rise and fall cycles of the environment where the outdoor LED display is located.

[0102] The first calculation module is used to calculate the number of cycles required for each solder joint on the outdoor LED display to reach solder joint failure, based on the temperature fluctuation difference and the highest temperature value corresponding to each temperature rise and fall cycle.

[0103] The second calculation module is used to determine the angle between the orientation of the outdoor LED display screen and the direction of direct sunlight, and to calculate the stress amplification factor of each solder joint in combination with the distance between each solder joint and the center point of the printed circuit board.

[0104] The third calculation module is used to calculate the cumulative damage value of multiple solder joints based on the stress amplification factor of each solder joint and the number of cycle times corresponding to multiple temperature rise and fall cycles.

[0105] The generation module is used to identify faulty solder joints based on the cumulative damage values ​​of multiple solder joints, predict the corresponding failure time based on the cumulative damage values ​​of the faulty solder joints, and generate maintenance instructions for the outdoor LED display screen based on the location and failure time of the faulty solder joints.

[0106] The predictive maintenance system for outdoor LED displays in this application is used to implement the aforementioned predictive maintenance method for outdoor LED displays. Therefore, the specific implementation of the predictive maintenance system for outdoor LED displays can be found in the embodiment section of the predictive maintenance method for outdoor LED displays above. The specific implementation can be referred to the description of the corresponding embodiments, which will not be repeated here.

[0107] This application also provides an electronic device, comprising: a memory for storing a computer program; and a processor for executing the computer program to implement the steps of the predictive maintenance method for outdoor LED displays described above.

[0108] This application also provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the steps of any of the above-described predictive maintenance methods for outdoor LED displays.

[0109] In one exemplary embodiment, the aforementioned computer-readable storage medium may include, but is not limited to, various media capable of storing computer programs, such as USB flash drives, read-only memory, random access memory, portable hard drives, magnetic disks, or optical disks.

[0110] Embodiments of this application also provide a computer program product, which includes a computer program that, when executed by a processor, implements the steps in any of the above embodiments of the predictive maintenance method for outdoor LED displays.

[0111] Those skilled in the art will further recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0112] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, data stored, data displayed, etc.) involved in one or more embodiments of this specification are all information and data authorized by the user or fully authorized by all parties. Furthermore, the collection, use and processing of related data must comply with relevant laws, regulations and standards, and corresponding operation entry points are provided for users to choose to authorize or refuse.

[0113] The above provides a detailed description of the predictive maintenance method and system for outdoor LED displays provided in this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the embodiments above are merely for the purpose of helping to understand the method and its core ideas. It should be noted that those skilled in the art can make various improvements and modifications to this application without departing from its principles, and these improvements and modifications also fall within the protection scope of this application.

Claims

1. A predictive maintenance method for outdoor LED displays, characterized in that, include: Determine multiple temperature rise and fall cycles of the environment where the outdoor LED display screen is located; For each temperature rise and fall cycle, the number of cycle cycles required for each solder joint on the outdoor LED display to reach solder joint failure is calculated based on the temperature fluctuation difference and the highest temperature value corresponding to each temperature rise and fall cycle. Determine the angle between the orientation of the outdoor LED display screen and the direction of direct sunlight, and calculate the stress amplification factor of each solder joint based on the distance between each solder joint and the center point of the printed circuit board; The cumulative damage value of multiple solder joints is calculated based on the stress amplification factor of each solder joint and the number of cycle cycles corresponding to the multiple temperature rise and fall cycles. Based on the cumulative damage values ​​of multiple solder joints, the faulty solder joint is identified, and the corresponding failure time is predicted based on the cumulative damage value of the faulty solder joint. Based on the location of the faulty solder joint and the failure time, maintenance instructions for the outdoor LED display screen are generated.

2. The method according to claim 1, characterized in that, The process of determining the angle between the orientation of the outdoor LED display screen and the direction of direct sunlight, and calculating the stress amplification factor of each solder joint in conjunction with the distance between each solder joint and the center point of the printed circuit board, includes: Obtain the coordinates of the solder joint on the printed circuit board, calculate the distance of the solder joint from the center of the printed circuit board based on the coordinates, and use the distance as the position distance factor of the solder joint; Obtain the installation location and orientation information of the outdoor LED display screen, determine the direct sunlight direction based on the installation location and the current time, determine the orientation angle of the outdoor LED display screen based on the orientation information, calculate the angle between the orientation angle and the direct sunlight direction, and take the larger value between the cosine of the angle and zero as the solar incidence factor of the solder joint. The stress amplification factor of the weld joint is obtained by weighting and summing the position distance factor and the solar radiation incident factor according to a preset weight.

3. The method according to claim 1, characterized in that, The step of calculating the cumulative damage value of multiple solder joints based on the stress amplification factor of each solder joint and the number of cycle times corresponding to the multiple temperature rise and fall cycles includes: For each solder joint and each temperature rise / fall cycle, the stress amplification factor of the solder joint is multiplied by the reciprocal of the number of cycles corresponding to the temperature rise / fall cycle to obtain the single damage increase value caused by the temperature rise / fall cycle to the solder joint. For each solder joint, the increase in single-time damage caused by the multiple temperature rise and fall cycles is accumulated to obtain the cumulative damage value of the solder joint.

4. The method according to claim 1, characterized in that, The step of predicting the corresponding failure time based on the cumulative damage value of the faulty solder joint includes: Construct a power-law relationship between the damage growth rate of the faulty solder joint and the damage value of the faulty solder joint, wherein the power-law relationship includes a damage growth rate coefficient and a damage acceleration index. Using the cumulative damage value of the faulty solder joint as an initial condition, the power relation is integrated to obtain an analytical expression for the change of the damage value of the faulty solder joint over time. Based on the analytical expression, the time corresponding to when the damage value of the faulty solder joint reaches the preset damage threshold is calculated, and the time is determined as the fault time of the faulty solder joint.

5. The method according to claim 1, characterized in that, The determination of multiple temperature rise and fall cycles of the environment where the outdoor LED display screen is located includes: The temperature time series of the outdoor LED display screen within a preset period is obtained through the Industrial Internet; The temperature time series is processed using the rainflow counting method to extract multiple temperature rise and fall cycles from the temperature time series, and to obtain the temperature fluctuation difference and the highest temperature value corresponding to each temperature rise and fall cycle.

6. The method according to claim 1, characterized in that, The calculation of the number of cycle cycles required for each solder joint on the outdoor LED display to reach solder joint failure, based on the temperature fluctuation difference and the highest temperature value corresponding to each temperature rise and fall cycle, includes: For each solder joint on the outdoor LED display screen and for each temperature rise and fall cycle, the temperature fluctuation difference and the highest temperature value corresponding to the temperature rise and fall cycle are substituted into a preset solder joint fatigue life model to calculate the number of cycle cycles required for the solder joint to fail under the working conditions corresponding to the temperature rise and fall cycle.

7. The method according to claim 1, characterized in that, The step of determining the faulty solder joint based on the cumulative damage value of multiple solder joints includes: The cumulative damage values ​​of all solder joints on the outdoor LED display screen are compared, and the solder joint with the largest cumulative damage value is identified as the faulty solder joint.

8. The method according to claim 4, characterized in that, After identifying the faulty solder joint based on the cumulative damage values ​​of multiple solder joints, the process also includes: Obtain the location of the historical faulty solder joints of the outdoor LED display screen; Determine whether the location of the historical fault solder joint and the location of the fault solder joint are located in the same display cabinet; When the location of the historical fault solder joint and the location of the fault solder joint are located in the same display box, the damage growth rate coefficient is multiplied by a preset rate acceleration factor to obtain the accelerated damage growth rate coefficient, wherein the rate acceleration factor is greater than 1. The damage acceleration index is multiplied by a preset acceleration factor to obtain the accelerated damage acceleration index, wherein the acceleration factor is greater than 1. The failure time of the faulty solder joint is re-predicted using the accelerated damage growth rate coefficient and the accelerated damage acceleration index.

9. The method according to claim 1, characterized in that, The step of generating maintenance instructions for the outdoor LED display screen based on the location and time of the faulty solder joint includes: Based on the location of the faulty solder joint, determine the display cabinet number and printed circuit board number corresponding to the faulty solder joint on the outdoor LED display screen; The execution time of the maintenance command is obtained by subtracting the preset lead time from the fault time. The display cabinet number, the printed circuit board number, the location of the faulty solder joint, and the execution time are encapsulated into a maintenance instruction and sent to the maintenance terminal.

10. A predictive maintenance system for outdoor LED displays, characterized in that, include: The determination module is used to determine multiple temperature rise and fall cycles of the environment where the outdoor LED display is located; The first calculation module is used to calculate the number of cycle cycles required for each solder joint on the outdoor LED display to reach solder joint failure, based on the temperature fluctuation difference and the highest temperature value corresponding to each temperature rise and fall cycle. The second calculation module is used to determine the angle between the orientation of the outdoor LED display screen and the direction of direct sunlight, and to calculate the stress amplification factor of each solder joint in combination with the distance between each solder joint and the center point of the printed circuit board. The third calculation module is used to calculate the cumulative damage value of multiple solder joints based on the stress amplification factor of each solder joint and the number of cycle cycles corresponding to the multiple temperature rise and fall cycles. The generation module is used to determine the faulty solder joint based on the cumulative damage value of multiple solder joints, predict the corresponding failure time based on the cumulative damage value of the faulty solder joint, and generate maintenance instructions for the outdoor LED display screen based on the location and failure time of the faulty solder joint.

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