Method and system for evaluating service life of electric actuating mechanism based on dynamic load monitoring

Abstract

The invention discloses an electric actuating mechanism service life evaluation method and system based on dynamic load monitoring, and particularly relates to the technical field of service life evaluation. For a fretting wear accumulation effect caused by resonance of a load frequency spectrum and a mechanical gap and lubricating oil film fracture reconstruction lag caused by the fact that the load change rate exceeds a critical value, an output shaft torque signal is collected for time-frequency domain conversion, and a load change frequency spectrum and a load change rate are obtained; and in combination with oil film state monitoring, the lubrication state deterioration risk and the wear accumulation effect are evaluated, and the failure critical risk is determined. When the failure critical risk is lower than a safety threshold value, analyzing contact surface stress distribution through a finite element to evaluate the wear degree, predicting the residual life by combining the failure threshold value of the similar electric actuating mechanism in a historical database, and judging whether the electric actuating mechanism needs to be maintained or replaced in advance, so that the actual wear and failure trend of the electric actuating mechanism under multiple working conditions can be accurately reflected; and the scientificity of maintenance decision and the operation safety are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of life assessment, and more specifically, to a method and system for assessing the life of an electric actuator based on dynamic load monitoring. Background Art

[0002] As a core component in the field of industrial automation and precision manufacturing, the reliability of electric actuators directly affects the operation of equipment. Existing life assessment methods are mostly based on linear wear models, which do not fully consider the nonlinear cumulative effect of micro-motion wear caused by the dynamic load spectrum characteristics and the resonance of the internal mechanical clearance of the mechanism, as well as the transient degradation of the lubrication state caused by the hysteresis of the lubricating oil film rupture and reconstruction triggered by the load change rate. In actual situations, load fluctuations and dynamic failure of the oil film accelerate the wear of the contact surface, severely shorten the life of the equipment, and pose a major safety hazard.

[0003] In order to solve the above problems, a technical solution is now provided. Summary of the invention

[0004] In order to overcome the above-mentioned defects of the prior art, the embodiments of the present invention provide a method and system for evaluating the life of an electric actuator based on dynamic load monitoring to solve the problems raised in the above-mentioned background technology.

[0005] To achieve the above object, the present invention provides the following technical solutions: The life assessment method of electric actuator based on dynamic load monitoring includes the following steps: The dynamic torque signal of the output shaft of the electric actuator is collected and processed in the time-frequency domain to obtain the load change spectrum and load change rate; By analyzing the load variation spectrum and the resonance response of the mechanical clearance inside the electric actuator, the nonlinear cumulative effect of fretting wear is evaluated. Monitor the oil film status in the electric actuator, analyze the triggering effect of load change rate on the dynamic rupture and reconstruction hysteresis of the oil film, and evaluate the risk of transient degradation of the lubrication status; Determine the critical failure risk of the electric actuator based on the nonlinear cumulative effect of fretting wear and the risk of transient degradation of lubrication status; When the critical failure risk of the electric actuator is lower than the safety threshold, the stress distribution of the contact surface is analyzed by finite element analysis to evaluate the wear degree of the electric actuator; Based on the degree of wear of the electric actuator and the failure threshold of similar electric actuators in the historical electric actuator operation database, the remaining life of the electric actuator is predicted and it is determined whether maintenance or replacement is required in advance.

[0006] In a preferred embodiment, the dynamic torque signal of the output shaft of the electric actuator is collected and processed in the time-frequency domain to obtain the load change spectrum and the load change rate, specifically: The torque sensor is used to continuously collect the dynamic torque signal of the output shaft of the electric actuator to obtain the original torque data; Perform signal denoising preprocessing on the collected raw torque data; The pre-processed torque signal is processed by fast Fourier transform to obtain the load variation spectrum of the output shaft of the electric actuator; The pre-processed torque signal is numerically differentiated to obtain the load change rate of the output shaft of the electric actuator.

[0007] In a preferred embodiment, the nonlinear cumulative effect of micro-motion wear is evaluated by analyzing the load variation spectrum and the resonance response of the mechanical clearance inside the electric actuator, specifically: Measure the size parameters of the mechanical gap inside the electric actuator and obtain the natural frequency of the mechanical gap; Compare the characteristic frequency in the load variation spectrum with the natural frequency of the mechanical gap to determine the resonant frequency that is the same as the natural frequency of the mechanical gap; Based on the resonance frequency, identify the micro-relative motion area and corresponding contact surface of the internal mechanical gap of the electric actuator under the resonance state; The amplitude and number of micro-relative motions at the contact surface are used to evaluate the extent of the nonlinear cumulative effect of fretting wear.

[0008] In a preferred embodiment, the oil film state in the electric actuator is monitored, the triggering effect of the load change rate on the dynamic rupture and reconstruction hysteresis of the oil film is analyzed, and the risk of transient degradation of the lubrication state is evaluated, specifically: The oil film pressure sensor is used to collect the oil film pressure data during the operation of the electric actuator; Time-matching of oil film pressure data and load change rate to identify oil film rupture caused by load fluctuations; The time it takes for the oil film to recover from a ruptured state to a stable state is recorded and determined as the duration of the oil film reconstruction lag; The risk of transient degradation of the lubrication state of the electric actuator is evaluated based on the duration of the oil film reconstruction lag and the fluctuation amplitude of the oil film pressure data.

[0009] In a preferred embodiment, based on the nonlinear cumulative effect of fretting wear and the risk of transient degradation of lubrication state, the critical failure risk of the electric actuator is determined as follows: When the wear accumulation parameter is greater than or equal to the wear accumulation parameter threshold, and the degradation risk parameter is greater than or equal to the degradation risk parameter threshold, it is determined that the critical failure risk of the electric actuator is lower than the safety threshold; otherwise, it is determined that the critical failure risk of the electric actuator is higher than the safety threshold.

[0010] In a preferred embodiment, when the critical risk of failure of the electric actuator is lower than the safety threshold, the wear degree of the electric actuator is evaluated by finite element analysis of the stress distribution of the contact surface, specifically: Establish the geometric model of the mechanical contact surface inside the electric actuator; Based on the load variation spectrum and load variation rate, the dynamic load on the mechanical contact surface is determined as the load boundary condition for finite element analysis; Set the material property parameters of finite element analysis according to the actual elastic modulus, Poisson's ratio and density of the mechanical contact surface material; Divide the finite element mesh, load the dynamic load to the finite element mesh, and perform finite element stress calculation on the mechanical contact surface; Obtain the stress distribution cloud map of the mechanical contact surface, determine the maximum stress value and the average stress value on the mechanical contact surface, and calculate the wear degree parameters of the contact surface.

[0011] In a preferred embodiment, based on the degree of wear of the electric actuator and in combination with the failure threshold of similar electric actuators in the historical electric actuator operation database, the remaining life of the electric actuator is predicted, and it is determined whether maintenance or replacement is required in advance, specifically: Obtain the failure threshold of similar electric actuators and use data interpolation method to calculate the remaining effective operating time of the electric actuators; Compare the remaining effective operating time of the electric actuator with the preset safe life to determine whether the electric actuator needs to be repaired or replaced in advance.

[0012] On the other hand, the present invention provides an electric actuator life assessment system based on dynamic load monitoring, including a signal acquisition and processing module, a fretting wear assessment module, a lubrication state monitoring module, a failure risk assessment module, a finite element analysis module, and a remaining life prediction module; The signal acquisition and processing module acquires the dynamic torque signal of the output shaft of the electric actuator, performs time-frequency domain conversion processing, and obtains the load change spectrum and load change rate; The fretting wear assessment module evaluates the nonlinear cumulative effect of fretting wear by analyzing the load variation spectrum and the resonance response of the mechanical clearance inside the electric actuator. The lubrication status monitoring module monitors the oil film status in the electric actuator, analyzes the triggering effect of the load change rate on the dynamic rupture and reconstruction hysteresis of the oil film, and evaluates the risk of transient degradation of the lubrication status; The failure risk assessment module determines the critical failure risk of the electric actuator based on the nonlinear cumulative effect of fretting wear and the risk of transient degradation of lubrication status; Finite element analysis module: When the critical failure risk of the electric actuator is lower than the safety threshold, the stress distribution of the contact surface is analyzed by finite element to evaluate the wear degree of the electric actuator; The remaining life prediction module predicts the remaining life of the electric actuator based on the degree of wear of the electric actuator and the failure threshold of similar electric actuators in the historical electric actuator operation database, and determines whether maintenance or replacement is required in advance.

[0013] Technical effects and advantages of the electric actuator life assessment method and system based on dynamic load monitoring of the present invention: By collecting the output shaft torque signal and obtaining the load change spectrum and rate through time-frequency domain conversion, the nonlinear cumulative effect of micro-motion wear caused by the resonance of the mechanical clearance inside the mechanism is revealed. At the same time, the oil film pressure state is monitored, the load fluctuation triggers the oil film rupture and reconstruction hysteresis, and the transient degradation risk of the lubrication state is evaluated. The critical failure risk is determined based on the risk of micro-motion wear and lubrication degradation. When the critical failure risk is lower than the safety threshold, the degree of wear is evaluated through finite element analysis of the contact surface stress distribution. The interpolation method is used to predict the remaining life in combination with historical operating data and failure thresholds, and timely determine whether it needs to be repaired or replaced in advance, which improves the accuracy of life prediction, reduces operating risks, extends the service life, and improves the safety and economic benefits of electric actuators. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic diagram of the life assessment method of the electric actuator based on dynamic load monitoring of the present invention; Figure 2 It is a structural schematic diagram of the electric actuator life assessment system based on dynamic load monitoring of the present invention. DETAILED DESCRIPTION

[0015] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0016] Embodiment 1:

[0017] Figure 1 The present invention provides a method for evaluating the life of an electric actuator based on dynamic load monitoring, which comprises the following steps: The dynamic torque signal of the output shaft of the electric actuator is collected and processed in the time-frequency domain to obtain the load change spectrum and load change rate; By analyzing the load variation spectrum and the resonance response of the mechanical clearance inside the electric actuator, the nonlinear cumulative effect of fretting wear is evaluated. Monitor the oil film status in the electric actuator, analyze the triggering effect of load change rate on the dynamic rupture and reconstruction hysteresis of the oil film, and evaluate the risk of transient degradation of the lubrication status; Determine the critical failure risk of the electric actuator based on the nonlinear cumulative effect of fretting wear and the risk of transient degradation of lubrication status; When the critical failure risk of the electric actuator is lower than the safety threshold, the stress distribution of the contact surface is analyzed by finite element analysis to evaluate the wear degree of the electric actuator; Based on the degree of wear of the electric actuator and the failure threshold of similar electric actuators in the historical electric actuator operation database, the remaining life of the electric actuator is predicted and it is determined whether maintenance or replacement is required in advance.

[0018] Specifically, the dynamic torque signal of the output shaft of the electric actuator is collected and processed in the time-frequency domain to obtain the load change spectrum and load change rate, including: The torque sensor is used to continuously collect the dynamic torque signal of the output shaft of the electric actuator under different operating conditions to obtain the raw torque data of the continuous time series: the dynamic torque sensor is installed on the output shaft of the electric actuator. The output end of the dynamic torque sensor is connected to the data acquisition device, which continuously samples the output signal of the torque sensor at a preset time interval to obtain the raw torque data of the time series. The raw torque data is defined as: ;in, The torque signal set that represents the change over time is a set of torque data collected from the output shaft of the entire electric actuator at different time points, reflecting the load on the output shaft during operation; Indicates that at the sampling time The torque value, ; Indicates the total number of sampling points; represents the time variable; Indicates the index of the sampling point.

[0019] in, is the starting sampling time; Represents the sampling time interval. The selection of the sampling interval needs to satisfy the signal sampling theorem to ensure that the highest frequency component does not exceed the Nyquist frequency to avoid aliasing.

[0020] The collected raw torque data is preprocessed to remove noise and obtain the preprocessed torque signal: a sliding average filter is used to suppress random noise and mutation signals in the raw torque data to smooth the signal and retain the effective signal components. The processed signal is expressed as: ;in, Represents the torque signal after preprocessing; after the torque signal is processed by the sliding average filter, it can suppress random noise and abnormal interference and retain the main change trend of the signal; Indicates the number of points in the sliding average filter window, that is, the total number of sampling points involved in the average calculation before and after the current moment; Indicates that at the sampling time The torque value of Represents the index variable in the sum operation, and its value range is arrive .

[0021] The pre-processed torque signal is processed by fast Fourier transform to obtain the amplitude distribution of the torque signal at different frequencies, and the load change spectrum of the output shaft of the electric actuator is obtained: the pre-processed torque signal is processed by fast Fourier transform in time-frequency domain to obtain the load change spectrum. The pre-processed torque signal is , and its fast Fourier transform result is expressed as: ;in, Indicates the frequency The Fourier transform result at , i.e. the complex number representation in the frequency domain, reflects the complex amplitude of each frequency component in the torque signal and is used to obtain the amplitude distribution of each frequency component; Indicates that at the sampling time Torque signal after preprocessing; represents an imaginary unit; Represents a frequency variable.

[0022] Through Modulo, get the load change spectrum: ;in, Indicates the frequency The signal amplitude below.

[0023] The peak frequency and its corresponding amplitude in the load variation spectrum are important bases for evaluating the nonlinear cumulative effect of fretting wear.

[0024] The pre-processed torque signal is numerically differentiated to obtain the load change rate of the output shaft of the electric actuator: The pre-processed torque signal data set is numerically differentiated to obtain the load change rate of the output shaft of the electric actuator.

[0025] The preprocessed torque signal data set is defined as: ;in, Represents the preprocessed torque signal dataset.

[0026] The formula for calculating the load change rate is: ;in, Indicates that at the sampling time The load change rate calculated at reflects the dynamic change speed of the torque signal.

[0027] Specifically, the nonlinear cumulative effect of micro-motion wear is evaluated by analyzing the load variation spectrum and the resonance response of the mechanical clearance inside the electric actuator, including: Measure the dimensional parameters of the mechanical gap inside the electric actuator and obtain the natural frequency of the mechanical gap: In order to evaluate the vibration characteristics of the mechanical gap inside the electric actuator, it is necessary to first measure the dimensional parameters of the mechanical gap and then calculate its natural frequency. The dimensional parameters of the mechanical gap are obtained by direct measurement, and then the equivalent stiffness and equivalent mass are calculated.

[0028] The function for calculating equivalent stiffness is defined as: ;in, Represents the equivalent stiffness of mechanical clearance; represents the function for calculating equivalent stiffness; Indicates the actual size parameter of the mechanical clearance; Indicates the elastic modulus of the material of the components involved in vibration analysis.

[0029] At the same time, the function for calculating equivalent mass is defined as: ;in, Represents the equivalent mass associated with mechanical clearance; represents the function for calculating equivalent mass; It represents the sum of the masses of the parts; It represents the structural distribution parameter and reflects the mass distribution.

[0030] Using the classical single-degree-of-freedom vibration theory, the natural frequency of the mechanical gap is expressed by the formula: ;in, Indicates the natural frequency of mechanical clearance.

[0031] Compare the characteristic frequency in the load change spectrum with the natural frequency of the mechanical gap to determine the resonant frequency that is the same as the natural frequency of the mechanical gap: Filter out the characteristic frequency that is consistent with the natural frequency of the mechanical gap in the load change spectrum. Define the tolerance threshold as , which indicates the allowable frequency deviation tolerance.

[0032] The resonant frequency determination conditions are: , for any frequency in the load variation spectrum If the absolute value of the difference between the natural frequency of the mechanical gap and the natural frequency of the mechanical gap is less than the tolerance threshold, the frequency is considered Resonance occurs with mechanical clearance.

[0033] By traversing all frequencies in the load variation spectrum, the frequencies that meet the conditions are selected as the resonant frequency set, which is recorded as: ;in, Represents the resonant frequency set, which contains all frequencies that meet the resonance conditions.

[0034] Based on the resonance frequency, the micro-relative motion area and the corresponding contact surface of the mechanical gap inside the electric actuator under the resonance state are identified: After the resonance frequency is determined, the resonance frequency is used to identify the micro-relative motion area caused by resonance in the mechanical gap inside the electric actuator. It is defined that under the resonance condition, the vibration amplitude distribution in the mechanical gap is expressed by a function as follows: ;in, Indicates the position in space The vibration amplitude; represents the function describing the variation of vibration amplitude with spatial position; represents the selected resonant frequency, satisfying ; Indicates a certain spatial position of the mechanical contact surface.

[0035] Define the vibration amplitude threshold as , which indicates the minimum vibration amplitude threshold for judging slight relative motion.

[0036] According to the vibration amplitude threshold, the identification of the slight relative motion area can be expressed as: ;in, Represents the slight relative motion area, which is the set of all positions where the vibration amplitude is greater than the threshold.

[0037] The corresponding contact surface is in the area of ​​slight relative motion. The actual contact surface of the mechanical parts inside, its position and shape are determined by the structural design.

[0038] The amplitude and number of micro-relative motions at the contact surface are used to evaluate the degree of nonlinear cumulative effect of micro-motion wear: Based on the micro-relative motion area under resonance And the corresponding contact surface, combined with the vibration amplitude and the number of movements to quantitatively evaluate the wear accumulation. At , the number of micro-relative motions is , indicating that at position The total number of micro-relative motions detected at

[0039] The wear accumulation parameter is calculated comprehensively using the vibration amplitude and the total number of micro-relative motions, and the wear accumulation parameter is defined as: ;in, represents the wear accumulation parameter; Indicates the number of sampling points contained in the micro-relative motion area.

[0040] By calculating the wear accumulation parameters, the nonlinear wear accumulation effect caused by the slight relative motion in the mechanical gap under the resonance state can be quantitatively evaluated, thus providing a basis for the life evaluation of the mechanism.

[0041] The larger the wear accumulation parameter, the more obvious the nonlinear cumulative effect of micro-motion wear inside the electric actuator. A higher wear accumulation parameter means that during the operation of the electric actuator, due to the dynamic load and mechanical clearance resonance, the amplitude and frequency of the micro-relative motion generated on the contact surface have increased, resulting in rapid increase in fatigue damage and surface wear of local materials, reflecting a high degree of structural degradation of key components, affecting overall reliability and remaining life; the larger the wear accumulation parameter, the worse the operating state of the electric actuator, and the need to strengthen monitoring and take timely maintenance or replacement measures to ensure safe and stable operation of the equipment.

[0042] Specifically, the oil film state in the electric actuator is monitored, the triggering effect of the load change rate on the dynamic rupture and reconstruction hysteresis of the oil film is analyzed, and the risk of transient degradation of the lubrication state is evaluated, including: Use oil film pressure sensor to collect oil film pressure data during the operation of electric actuator: In the lubrication system of electric actuator, configure oil film pressure sensor to collect oil film pressure data during operation. Set the oil film pressure data to , indicating that at a point in time The oil film pressure value collected. The oil film pressure data sampling time interval is expressed as .

[0043] Match the oil film pressure data with the load change rate in time to identify oil film rupture caused by load fluctuations: To match the oil film pressure data with the load change rate in time, the sampling time interval needs to be guaranteed. and Meet the synchronization requirements or align through interpolation methods. After matching, use the matched time axis to analyze the oil film pressure data and identify the oil film rupture caused by load fluctuations.

[0044] Using continuous sampling data, the oil film rupture is determined by calculating the difference in oil film pressure between adjacent sampling points. The oil film pressure change is defined as: ;in, Indicates from the time point arrive The change in oil film pressure.

[0045] The pressure change threshold is preset. When the oil film pressure change is less than the negative pressure change threshold, it is considered that the oil film is ruptured. It is the triggering moment of oil film rupture; the pressure change threshold is determined according to experimental data or equipment characteristics.

[0046] The time it takes for the oil film to recover from a ruptured state to a stable state is recorded, and this is determined as the duration of the oil film reconstruction lag: After the oil film ruptures, the oil film pressure data will drop significantly, and then the oil film will undergo a dynamic reconstruction process until it returns to a stable state. In order to quantify the oil film reconstruction lag time, it is necessary to record the time from when the oil film ruptures to when the oil film pressure returns to a stable state.

[0047] Define the steady state pressure as , which represents the reference pressure value of the oil film in a stable state.

[0048] The allowable deviation is defined as , when the oil film pressure meets When , the oil film is considered to have returned to a stable state. For recovery time.

[0049] Oil film reconstruction lag time Defined as: ;in, The oil film reconstruction lag time indicates the time required for the oil film to recover from a ruptured state to a stable state; It is the triggering moment of oil film rupture; This is the moment when the oil film returns to a stable state.

[0050] By recording and counting the oil film reconstruction lag time, the distribution of the oil film reconstruction lag time is obtained, providing a quantitative basis for risk assessment.

[0051] According to the duration of the oil film reconstruction lag and the fluctuation amplitude of the oil film pressure data, the risk of transient degradation of the lubrication state of the electric actuator is evaluated: In order to evaluate the risk of transient degradation of the lubrication state of the electric actuator, the oil film pressure fluctuation amplitude parameter is introduced. It is defined that during the oil film rupture process, the minimum oil film pressure , then the oil film pressure fluctuation amplitude is defined as: ;in, is the oil film pressure fluctuation amplitude, which indicates the drop of oil film pressure from the stable state to the minimum value; Indicates the minimum pressure value detected during the rupture process of the oil film pressure.

[0052] Based on the combined influence of the duration of oil film reconstruction lag and the amplitude of oil film pressure fluctuation, a degradation risk parameter is constructed, and its calculation formula is: ;in, represents the degradation risk parameter; is a weight factor used to adjust the contribution of the oil film reconstruction lag time in risk assessment; is a weight factor used to adjust the contribution of the oil film pressure fluctuation amplitude in risk assessment. and The value of is determined based on experimental verification and the characteristics of the electric actuator.

[0053] The larger the degradation risk parameter, the slower the recovery of the oil film after it breaks during operation, the more severe the oil film pressure fluctuations, and the difficulty of the lubricating oil film to recover to a stable state in time, which leads to a significant reduction in the lubrication effect. A larger degradation risk parameter means that the oil film failure phenomenon is frequent and lasts for a long time, and the local lubrication conditions deteriorate seriously, which increases the friction and accelerates the wear between mechanical parts, reduces the overall operation reliability, and indicates that the electric actuator may be at risk of premature failure.

[0054] Specifically, based on the nonlinear cumulative effect of fretting wear and the risk of transient degradation of lubrication status, the critical failure risk of the electric actuator is determined, including: A wear accumulation parameter threshold is preset, and the wear accumulation parameter is compared with the wear accumulation parameter threshold: When the wear accumulation parameter is greater than or equal to the wear accumulation parameter threshold, it indicates that the accumulated degree of micro-motion wear inside the electric actuator has reached or exceeded the critical range, which may cause excessive fatigue of the contact surface or a significant decline in performance. It is necessary to take immediate measures such as maintenance, replacement or enhanced monitoring to avoid further deterioration of key components of the electric actuator; When the wear accumulation parameter is less than the wear accumulation parameter threshold, it means that the micro-motion wear is within the critical range and the electric actuator can operate safely within the established working cycle. However, it is still necessary to regularly evaluate the wear development trend and adjust the maintenance strategy in time according to the evaluation results.

[0055] The wear accumulation parameter threshold is determined based on a large amount of actual test data and long-term application experience. By sampling and analyzing the degree of micro-motion wear of the contact surface under different operating conditions, the failure probability of each component under different cumulative wear conditions is summarized, and corrected by combining factors such as material properties, ambient temperature, load spectrum and safety margin, a numerical range reflecting the critical wear level is obtained.

[0056] A degradation risk parameter threshold is preset, and the degradation risk parameter is compared with the degradation risk parameter threshold: When the degradation risk parameter is greater than or equal to the degradation risk parameter threshold, it means that the lubricating oil film is frequently broken or rebuilt late due to dynamic load changes, the lubrication state is rapidly deteriorated, and the local lubrication effect is reduced, resulting in increased friction and accelerated wear; When the degradation risk parameter is less than the degradation risk parameter threshold, it means that the lubricating oil film recovers quickly and the pressure fluctuation is small, the number of oil film ruptures or the reconstruction lag time is within a controllable range, and the electric actuator can continue to operate according to the regular maintenance plan.

[0057] The threshold of the degradation risk parameter is based on key indicators such as oil film pressure sampling data, oil film reconstruction lag time and load change rate, and is obtained through statistical analysis and field test verification. Specifically, we first collect information such as the oil film rupture frequency, minimum pressure value and recovery time in different operating stages to evaluate the impact on the lubrication system under dynamic conditions, and then combine the equipment failure rate and economic considerations in actual conditions to summarize the correlation and safety boundaries between the values, and select the key values ​​that can distinguish between normal lubrication and severe degradation as the threshold.

[0058] When the wear accumulation parameter is greater than or equal to the wear accumulation parameter threshold, and the degradation risk parameter is greater than or equal to the degradation risk parameter threshold, it is determined that the critical failure risk of the electric actuator is lower than the safety threshold; otherwise, it is determined that the critical failure risk of the electric actuator is higher than the safety threshold.

[0059] Specifically, when the critical failure risk of the electric actuator is lower than the safety threshold, the stress distribution of the contact surface is analyzed by finite element analysis to evaluate the wear degree of the electric actuator, including: Establish the geometric model of the mechanical contact surface inside the electric actuator: Construct the geometric model of the mechanical contact surface inside the electric actuator based on the actual measurement data, denoted as , represents the spatial region where the mechanical contact surface is located, and its range is determined by the contour and size of the actual parts. The set of discrete nodes in the spatial region is recorded as Each of these Indicates The three-dimensional coordinates of the nodes; Indicates the total number of nodes. The geometric model is obtained through 3D scanning or precise measurement, which can reflect the actual shape and size of the contact surface and provide an accurate basis for finite element meshing.

[0060] Based on the load change spectrum and load change rate, the dynamic load on the mechanical contact surface is determined as the load boundary condition for finite element analysis: According to the load change spectrum and load change rate, the dynamic load acting on the mechanical contact surface is determined. The dynamic load intensity is defined as: ;in, Indicates dynamic load strength; Indicates frequency components Total number of; Indicates the load variation spectrum. Frequency The amplitude of Indicates the corresponding frequency The rate of load change under .

[0061] The calculated dynamic load intensity is used as the boundary load condition during finite element analysis, reflecting the dynamic force borne by the contact surface under actual working conditions, ensuring that the finite element calculation can truly simulate the load effect.

[0062] According to the actual elastic modulus, Poisson's ratio and density of the mechanical contact surface material, the material property parameters of the finite element analysis are set; according to the actual physical properties of the mechanical contact surface material, the material property parameters in the finite element analysis are set, including: : is the actual elastic modulus of the material, reflecting the stress-strain relationship of the material within the elastic range; : Poisson's ratio of the material, which describes the ratio of the lateral strain to the axial strain when the material is under compression or tension; : is the material density, which determines the inertial characteristics of the material.

[0063] The above parameters are obtained through material experiments or data provided by manufacturers and used as input of material properties in finite element calculations to ensure that the simulation results are consistent with the actual situation.

[0064] Divide the finite element mesh, load the dynamic load to the finite element mesh, and perform finite element stress calculation on the mechanical contact surface; The mechanical contact surface is meshed by finite element. The geometric model is divided into units, whose collection is recorded as ;in Represents a collection of units; is the total number of units. The shape and size of each unit are determined according to the local geometric characteristics of the contact surface to ensure that the mesh size meets the calculation accuracy requirements. Subsequently, the dynamic load intensity is loaded onto the corresponding boundary of the finite element mesh and applied to each unit as a load boundary condition. The finite element method uses the interpolation function between nodes to discretize and solve the entire model. The stress calculation formula in the unit is: ;in, Indicates that at the node The stress tensor calculated at ; is the derivative matrix of the formal function, whose specific form is determined by the selected unit type; For Node The displacement vector at .

[0065] By solving the entire mesh using a finite element solver, the stress distribution of the contact surface under dynamic loads can be obtained.

[0066] Obtain the stress distribution cloud map of the mechanical contact surface, extract the stress values ​​at each node position on the mechanical contact surface, and determine the maximum stress value and average stress value on the mechanical contact surface: After completing the finite element calculation, use numerical visualization technology to generate the stress distribution cloud map of the mechanical contact surface. The stress distribution cloud map intuitively displays each node The stress value at , reflecting the stress concentration area and distribution law. According to the cloud map data, the maximum stress value and average stress value on the mechanical contact surface are extracted: as well as ;in, Indicates the maximum stress value among all nodes on the mechanical contact surface; Represents the average stress value of all nodes on the mechanical contact surface.

[0067] The maximum stress value reflects the local stress concentration, while the average stress value describes the overall stress distribution level. Higher maximum stress and average stress values ​​usually indicate a greater wear risk at the mechanical contact surface, which may cause local fatigue damage.

[0068] According to the maximum stress value and average stress value on the mechanical contact surface, the wear degree parameter of the contact surface is calculated: According to the maximum stress value and average stress value extracted on the mechanical contact surface, the wear degree parameter is defined to reflect the difference between local stress concentration and overall stress distribution. The calculation formula is: ;in, Indicates the wear degree parameter.

[0069] The larger the wear degree parameter, the more serious the local stress concentration on the key contact surface inside the electric actuator, that is, the more serious the wear degree of the electric actuator. A higher wear degree parameter indicates that the electric actuator has accumulated significant wear risks in long-term operation and there is a risk of premature failure.

[0070] Specifically, based on the degree of wear of the electric actuator and the failure threshold of similar electric actuators in the historical electric actuator operation database, the remaining life of the electric actuator is predicted, and it is determined whether maintenance or replacement is required in advance, including: Obtain the failure threshold of similar electric actuators and use data interpolation to calculate the remaining effective operation time of the electric actuator: extract the failure threshold of similar electric actuators from the historical electric actuator operation database. Define the failure threshold as , represents the failure threshold, which is determined by statistical analysis of a large amount of historical data, material fatigue tests and engineering experience. It reflects that in actual operation, when the wear accumulation parameter reaches or exceeds the failure threshold, the electric actuator enters a failure state.

[0071] In order to calculate the remaining effective operating time of the electric actuator, the design life of the electric actuator in its entire life cycle is defined as , which indicates the expected total operating time of the electric actuator in the new state, is determined based on product design, manufacturer data or long-term operating experience.

[0072] Based on the data interpolation method, the calculation formula for the remaining effective running time is: ;in, Indicates the remaining effective operating time of the electric actuator.

[0073] Compare the remaining effective operating time of the electric actuator with the preset safe life to determine whether the electric actuator needs to be repaired or replaced in advance: Define the preset safety life of the electric actuator, which means the minimum remaining effective operating time required to ensure the safety and reliability of the electric actuator during operation.

[0074] The comparison rules are: When the remaining effective operating time of the electric actuator is greater than or equal to the preset safe life, it is predicted that the remaining life of the electric actuator is sufficient, the operating state of the electric actuator is within the safe range, and no maintenance or replacement measures are required; When the remaining effective operating time of the electric actuator is less than the preset safe life, it is predicted that the remaining life of the electric actuator is insufficient and maintenance or replacement measures are required.

[0075] Embodiment 2:

[0076] The difference between Example 2 of the present invention and Example 1 is that this example introduces a life assessment system for an electric actuator based on dynamic load monitoring.

[0077] Figure 2 A structural schematic diagram of the electric actuator life assessment system based on dynamic load monitoring of the present invention is given. The electric actuator life assessment system based on dynamic load monitoring includes a signal acquisition and processing module, a fretting wear assessment module, a lubrication state monitoring module, a failure risk assessment module, a finite element analysis module, and a remaining life prediction module; The signal acquisition and processing module acquires the dynamic torque signal of the output shaft of the electric actuator, performs time-frequency domain conversion processing, and obtains the load change spectrum and load change rate; The fretting wear assessment module evaluates the nonlinear cumulative effect of fretting wear by analyzing the load variation spectrum and the resonance response of the mechanical clearance inside the electric actuator. The lubrication status monitoring module monitors the oil film status in the electric actuator, analyzes the triggering effect of the load change rate on the dynamic rupture and reconstruction hysteresis of the oil film, and evaluates the risk of transient degradation of the lubrication status; The failure risk assessment module determines the critical failure risk of the electric actuator based on the nonlinear cumulative effect of fretting wear and the risk of transient degradation of lubrication status; Finite element analysis module: When the critical failure risk of the electric actuator is lower than the safety threshold, the stress distribution of the contact surface is analyzed by finite element to evaluate the wear degree of the electric actuator; The remaining life prediction module predicts the remaining life of the electric actuator based on the degree of wear of the electric actuator and the failure threshold of similar electric actuators in the historical electric actuator operation database, and determines whether maintenance or replacement is required in advance.

[0078] The above formulas are all dimensionless and numerical calculations. The formula is a formula for the most recent real situation obtained by collecting a large amount of data and performing software simulation. The preset parameters and thresholds in the formula are set by technicians in this field according to actual conditions.

[0079] The above embodiments may be implemented in whole or in part by software, hardware, firmware or any other combination thereof. When implemented by software, the above embodiments may be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions or computer programs. When the computer instructions or computer programs are loaded or executed on a computer, the process or function described in the embodiment of the present application is generated in whole or in part. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions may be stored in a computer-readable storage medium, or may be transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions may be transmitted from one website, computer, server or data center to another website, computer, server or data center by wired (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium may be any available medium that a computer can access or a data storage device such as a server or data center that contains one or more available media sets. The available medium may be a magnetic medium (e.g., a floppy disk, a hard disk, a tape), an optical medium (e.g., a DVD), or a semiconductor medium. The semiconductor medium may be a solid-state hard disk.

[0080] Those of ordinary skill in the art will appreciate that the modules and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0081] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and modules described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0082] In the several embodiments provided in the present application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the modules is only a logical function division. There may be other division methods in actual implementation, such as multiple modules or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or modules, which can be electrical, mechanical or other forms.

[0083] The modules described as separate components may or may not be physically separated, and the components shown as modules may or may not be physical modules, and may be located in one place or distributed on multiple network modules. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0084] In addition, each functional module in each embodiment of the present application may be integrated into one processing module, or each module may exist physically separately, or two or more modules may be integrated into one module.

[0085] If the functions are implemented in the form of software function modules and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application can be essentially or partly embodied in the form of a software product that contributes to the prior art. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the methods described in the various embodiments of the present application. The aforementioned storage media include: U disk, mobile hard disk, read-only memory (ROM), random access memory (RAM), disk or optical disk, and other media that can store program codes.

[0086] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

[0087] Finally: The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for evaluating the life of an electric actuator based on dynamic load monitoring, characterized in that: The steps include: The dynamic torque signal of the output shaft of the electric actuator is collected and processed in the time-frequency domain to obtain the load change spectrum and load change rate; By analyzing the load variation spectrum and the resonance response of the mechanical clearance inside the electric actuator, the nonlinear cumulative effect of fretting wear is evaluated. Monitor the oil film status in the electric actuator, analyze the triggering effect of load change rate on the dynamic rupture and reconstruction hysteresis of the oil film, and evaluate the risk of transient degradation of the lubrication status; Determine the critical failure risk of the electric actuator based on the nonlinear cumulative effect of fretting wear and the risk of transient degradation of lubrication status; When the critical failure risk of the electric actuator is lower than the safety threshold, the stress distribution of the contact surface is analyzed by finite element analysis to evaluate the wear degree of the electric actuator; Based on the degree of wear of the electric actuator and the failure threshold of similar electric actuators in the historical electric actuator operation database, the remaining life of the electric actuator is predicted and it is determined whether maintenance or replacement is required in advance.

2. The method for evaluating the life of an electric actuator based on dynamic load monitoring according to claim 1, characterized in that: The dynamic torque signal of the output shaft of the electric actuator is collected and processed in the time-frequency domain to obtain the load change spectrum and load change rate, which are as follows: The torque sensor is used to continuously collect the dynamic torque signal of the output shaft of the electric actuator to obtain the original torque data; Perform signal denoising preprocessing on the collected raw torque data; The pre-processed torque signal is processed by fast Fourier transform to obtain the load variation spectrum of the output shaft of the electric actuator; The pre-processed torque signal is numerically differentiated to obtain the load change rate of the output shaft of the electric actuator.

3. The method for evaluating the life of an electric actuator based on dynamic load monitoring according to claim 2 is characterized in that: By analyzing the load variation spectrum and the resonance response of the mechanical clearance inside the electric actuator, the nonlinear cumulative effect of micro-motion wear is evaluated, specifically: Measure the size parameters of the mechanical gap inside the electric actuator and obtain the natural frequency of the mechanical gap; Compare the characteristic frequency in the load variation spectrum with the natural frequency of the mechanical gap to determine the resonant frequency that is the same as the natural frequency of the mechanical gap; Based on the resonance frequency, identify the micro-relative motion area and corresponding contact surface of the internal mechanical gap of the electric actuator under the resonance state; The amplitude and number of micro-relative motions at the contact surface are used to evaluate the extent of the nonlinear cumulative effect of fretting wear.

4. The method for evaluating the life of an electric actuator based on dynamic load monitoring according to claim 3 is characterized in that: Monitor the oil film status in the electric actuator, analyze the triggering effect of load change rate on the dynamic rupture and reconstruction hysteresis of the oil film, and evaluate the risk of transient degradation of the lubrication status, specifically: The oil film pressure sensor is used to collect the oil film pressure data during the operation of the electric actuator; Time-matching of oil film pressure data and load change rate to identify oil film rupture caused by load fluctuations; The time it takes for the oil film to recover from a ruptured state to a stable state is recorded and determined as the duration of the oil film reconstruction lag; The risk of transient degradation of the lubrication state of the electric actuator is evaluated based on the duration of the oil film reconstruction lag and the fluctuation amplitude of the oil film pressure data.

5. The method for evaluating the life of an electric actuator based on dynamic load monitoring according to claim 4 is characterized in that: Based on the nonlinear cumulative effect of fretting wear and the risk of transient degradation of lubrication status, the critical failure risk of the electric actuator is determined, specifically: When the wear accumulation parameter is greater than or equal to the wear accumulation parameter threshold, and the degradation risk parameter is greater than or equal to the degradation risk parameter threshold, it is determined that the critical failure risk of the electric actuator is lower than the safety threshold; otherwise, it is determined that the critical failure risk of the electric actuator is higher than the safety threshold.

6. The method for evaluating the life of an electric actuator based on dynamic load monitoring according to claim 5 is characterized in that: When the critical failure risk of the electric actuator is lower than the safety threshold, the stress distribution of the contact surface is analyzed by finite element analysis to evaluate the wear degree of the electric actuator, specifically: Establish the geometric model of the mechanical contact surface inside the electric actuator; Based on the load variation spectrum and load variation rate, the dynamic load on the mechanical contact surface is determined as the load boundary condition for finite element analysis; Set the material property parameters of finite element analysis according to the actual elastic modulus, Poisson's ratio and density of the mechanical contact surface material; Divide the finite element mesh, load the dynamic load to the finite element mesh, and perform finite element stress calculation on the mechanical contact surface; Obtain the stress distribution cloud map of the mechanical contact surface, determine the maximum stress value and the average stress value on the mechanical contact surface, and calculate the wear degree parameters of the contact surface.

7. The method for evaluating the life of an electric actuator based on dynamic load monitoring according to claim 6, characterized in that: Based on the degree of wear of the electric actuator and the failure threshold of similar electric actuators in the historical electric actuator operation database, the remaining life of the electric actuator is predicted, and it is determined whether maintenance or replacement is required in advance. Specifically: Obtain the failure threshold of similar electric actuators and use data interpolation method to calculate the remaining effective operating time of the electric actuators; Compare the remaining effective operating time of the electric actuator with the preset safe life to determine whether the electric actuator needs to be repaired or replaced in advance.

8. An electric actuator life assessment system based on dynamic load monitoring, used to implement the electric actuator life assessment method based on dynamic load monitoring according to any one of claims 1 to 7, characterized in that: It includes signal acquisition and processing module, fretting wear assessment module, lubrication status monitoring module, failure risk assessment module, finite element analysis module and remaining life prediction module; The signal acquisition and processing module acquires the dynamic torque signal of the output shaft of the electric actuator, performs time-frequency domain conversion processing, and obtains the load change spectrum and load change rate; The fretting wear assessment module evaluates the nonlinear cumulative effect of fretting wear by analyzing the load variation spectrum and the resonance response of the mechanical clearance inside the electric actuator. The lubrication status monitoring module monitors the oil film status in the electric actuator, analyzes the triggering effect of the load change rate on the dynamic rupture and reconstruction hysteresis of the oil film, and evaluates the risk of transient degradation of the lubrication status; The failure risk assessment module determines the critical failure risk of the electric actuator based on the nonlinear cumulative effect of fretting wear and the risk of transient degradation of lubrication status; Finite element analysis module: When the critical failure risk of the electric actuator is lower than the safety threshold, the stress distribution of the contact surface is analyzed by finite element to evaluate the wear degree of the electric actuator; The remaining life prediction module predicts the remaining life of the electric actuator based on the degree of wear of the electric actuator and the failure threshold of similar electric actuators in the historical electric actuator operation database, and determines whether maintenance or replacement is required in advance.

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