302 results about "Fatigue loading" patented technology

The invention belongs to the technical field of nondestructive testing, and particularly relates to a detection method for quantitatively evaluating fatigue damage in a pipeline through a nonlinear ultrasonic technology. 316 stainless steel and SA335GRP-11 ferrite steel samples are adopted, a welding seam area is formed through V-shaped groove welding, fatigue loading is conducted, and actual pipeline fatigue damage is simulated; for the samples with different fatigue cycles, nonlinear response signals of the samples are obtained; fourier transform is carried out on the obtained signal to obtain an energy spectrum of the signal, and energy changes of the signal on a fundamental frequency band and a second harmonic frequency band are analyzed; and calculating a nonlinear coefficient, and analyzing a change rule of the nonlinear coefficient along with fatigue cycles, so that the evolution process of fatigue damage in the pipeline is evaluated. According to the method, energy is used for replacing the amplitude value, on the basis of the formula principle, integration is used for replacing the amplitude value to improve the intensity of the characterization nonlinear ultrasonic signal, the early stage of damage and the later stage of crack initiation are detected, and reliable guarantee is provided for safe operation of an industrial pipeline system.

An in-situ fretting corrosion fatigue testing machine based on synchrotron radiation diffraction and three-dimensional (3D) imaging includes an axial fatigue loading system, a fretting loading system, and a corrosion environment control system, where the axial fatigue loading system includes a driving device, a load control device, and a load sensing device; the load sensing device is configured to measure an axial force and a normal force in real time; the driving device is configured to drive the load control device, thereby achieving axial displacement of the load control device; the load control device is configured to carry out axial fatigue loading of a specimen; and the fretting loading system includes a fretting wear device. The testing machine achieves real-time 3D imaging characterization of wear spot and crack morphology of a material in a fretting corrosion environment, as well as characterization of a residual stress evolution law.

The invention discloses a fatigue load response analysis method for a non-uniform beam of a ship, and particularly relates to the technical field of fatigue load response analys.The vibration coupling degree between the non-uniform beam and other parts of the ship is judged by obtaining the inherent frequency of the non-uniform beam and the other parts of the ship and calculating the vibration coupling degree coefficient; the method comprises the following steps of: acquiring load time-history data of a non-uniform beam, generating a dynamic load spectrum of the non-uniform beam, effectively capturing real load conditions of a ship under various working conditions, and calculating a fatigue damage coefficient of the non-uniform beam through local stress-strain analysis of the non-uniform beam so as to obtain a dynamic load spectrum of the non-uniform beam. A self-adaptive fatigue damage model is constructed based on the vibration coupling degree coefficient and the fatigue damage coefficient, the fatigue damage value of the non-uniform beam is dynamically corrected, the fatigue damage evolution process of the non-uniform beam under different working conditions is reflected through self-adaptive adjustment, and the dynamic property and accuracy of fatigue damage evaluation are improved.

The invention provides a double-space fatigue electron microscope test system, which is applied to the technical field of material analysis, and comprises an electron microscope module, a fatigue loading module and a vacuum isolation damping module, the vacuum isolation damping module controls two spaces of the electron microscope module and the fatigue loading module to be communicated or independent; the fatigue loading module comprises a hydraulic loading actuator, an electromechanical loading actuator, a loading rod and a fixing clamp, the fixing clamp is used for clamping a to-be-tested sample, and the loading rod is used for stretching or extruding the to-be-tested sample; and the fatigue loading module is driven by the moving mechanism to reciprocate along the X axis to adjust the position of the to-be-tested sample or rotate along the X axis to realize switching of different stations. According to the double-space fatigue electron microscope test system, combined use or independent use of the electron microscope module and the fatigue loading module is realized, and adverse factors such as vibration and pulse generated by the fatigue loading module during electron microscope observation are improved; in-situ compensation is achieved by means of cooperation of loading force and displacement of the fatigue loading module, and the observation effect of the electron microscope is improved.

The invention relates to the technical field of load spectrum analysis, and discloses a gear random fatigue load processing method and system based on a GCM counting method.The method comprises the steps that actual operation load data and actual operation environment data of a gear transmission system are collected, and torque is converted into instantaneous contact stress; dividing into a plurality of discrete cells based on discretization processing; carrying out clustering analysis on all discrete cells; constructing a two-dimensional gear counting matrix; the asymmetric cyclic stress is converted into equivalent symmetric cyclic stress, and the total service life of the gear is determined; comparing the equivalent symmetric cyclic stress with cyclic stress under a raindrop counting method to determine an adjustment coefficient, and determining an early warning threshold value according to the total service life of the gear and the adjustment coefficient; and comparing the total fatigue damage value with an early warning threshold value to determine an early warning grade. According to the method, joint statistics of the stress amplitude, the average stress and the environmental characteristics is achieved, and the defects of a raindrop counting method in the aspects of processing meshing discontinuous loads and lacking environmental adaptability are overcome.

The present invention belongs to the technical field of wind farm active power control and discloses a wind farm frequency modulation power distribution method that takes into account the historical fatigue load of the unit. The method comprises the following steps: collecting the frequency data of the wind farm grid connection point; when the frequency change exceeds the frequency modulation dead zone, calculating the wind farm active power change reference value ΔP farm ; Match the station active power change reference value ΔP in the formed scenario strategy set farm The corresponding optimized active power distribution results of the units. This distribution method is compared with the traditional proportional distribution scheme. While meeting the system frequency response requirements, the present invention improves the problems of sudden increase in fatigue load in wind farms and large differences in fatigue accumulation between units, and verifies the effectiveness of the proposed method.

The invention provides a chain ring fatigue damage calculation method and system considering wear conditions, under the conditions of multiple working conditions and multiple wear losses, fatigue load calculation and accumulated damage analysis are carried out on a suspension chain ring, and through time domain simulation, finite element calculation, rain flow counting and S-N curve combination, the fatigue damage of the chain ring is calculated. And a working condition-abrasion loss-fatigue damage database is established. According to the method and the system, accurate evaluation and early warning can be provided for safe service management of the anchor chain or the suspension chain in ship and ocean engineering, and the reliability and the economical efficiency of system operation are greatly improved. All the parts of the device can be independently implemented and can also be modularly combined.

The invention provides a fatigue test method, system and equipment based on texture change of carbon fibers and a medium, and belongs to the technical field of material tests.The method comprises the steps that a carbon fiber composite material is selected as a test sample; applying a fatigue load to the test sample according to a designed test condition, and collecting a surface image of the test sample; the method comprises the following steps of: preprocessing an acquired image, clustering according to the gray level and texture similarity of pixels to obtain a plurality of clustering subareas, and marking different clustering areas by using different colors to complete color mapping; extracting texture feature parameters from the image after color mapping, and performing PCA dimension reduction to obtain key texture feature parameters; and comparing the key texture feature parameters of the image under different test conditions, identifying texture feature changes, and completing fatigue performance evaluation. According to the method, image processing and texture feature analysis are combined, so that non-destructive testing of the CFRP fatigue performance is realized, and the testing accuracy and efficiency are improved.

The invention relates to the technical field of metal fatigue life prediction, in particular to an additive manufacturing metal multi-axis high-cycle fatigue life prediction method based on defect characteristics. The method comprises the following steps: performing defect detection on a metal sample to obtain size parameters and position parameters of defects in the metal sample; determining the type of the defect in the metal sample and setting a first correction factor and a second correction factor; calculating the equivalent stress strength factor amplitude of the metal sample under multi-axial loading; acquiring a long crack propagation threshold value of the metal sample; normalizing the position parameters to obtain normalized position parameters; and establishing a fatigue life prediction model of the metal sample according to the normalized position parameters, the equivalent stress strength factor amplitude of the metal sample under multi-axial loading and the long crack propagation threshold value of the metal sample, and calculating the multi-axial high-cycle fatigue life of the metal sample. According to the method, the fatigue life of the metal material containing the additive manufacturing defects under multi-axis high-cycle fatigue loading can be accurately predicted.

The invention relates to a non-probabilistic fatigue reliability analysis method for a controllable-pitch propeller hub mechanism under data driving, which comprises the following steps of: considering multiple uncertain sources such as elastic modulus and friction coefficient, modeling each part of the controllable-pitch propeller hub mechanism through parameterization to obtain a finite element model under different uncertain variable values; drawing a fatigue load spectrum by using a finite element simulation load result, and performing fatigue simulation by combining an S-N curve to obtain the fatigue life of each part; and obtaining a non-probability interval model of the fatigue life of each part by using a data-driven agent model and a Monte Carlo method under a limited fatigue life sample condition, and calculating the fatigue reliability of each part by using a non-probability area method. A data driving method is adopted, so that the problems of high cost and time consumption of obtaining enough data in actual engineering are avoided; fatigue reliability analysis is carried out by adopting a non-probabilistic method, so that uncertainty in engineering can be better dealt with, and the fatigue reliability of the controllable-pitch propeller hub mechanism can be more comprehensively evaluated.

The invention provides a test device and a test method for loading a three-dimensional conical fatigue load. The device comprises a bearing beam frame assembly, a sliding rod supporting assembly, a displacement coordination loading system, an axial force loading system, a stay cable simulation test piece and a stay cable simulation fixing tool, by analyzing the working states of flexible connecting structural members such as inhaul cables and mooring ropes, the invention provides a new fatigue loading form, and the loaded axial force is always in the axial direction of the structural members and can rotate in the space; the loading form can truly reflect the'pull-pull 'fatigue life of the structural member in a specific working environment, and is used for guiding maintenance and repair of key equipment.

The invention discloses a neural network-based turbine blade high-low cycle composite fatigue reliability analysis method, which comprises the following steps of: obtaining a small amount of data samples of a turbine blade through finite element analysis, extracting the characteristics of the data samples by using a convolutional neural network, and inputting the extracted characteristics into a BP neural network optimized by an improved seagull optimization algorithm to obtain the high-low cycle composite fatigue reliability of the turbine blade. The method comprises the following steps: establishing a CNN-MSOA-BP neural network model of a turbine blade under a high-low cycle composite fatigue load, taking multi-source uncertainty such as a load parameter and a material parameter into consideration, sampling a large number of input samples through Monte Carlo, and obtaining a corresponding output response through the established CNN-MSOA-BP neural network model, thereby performing reliability analysis of the turbine blade. According to the method provided by the invention, the reliability of the turbine structure under complex loads such as high-low cycle compound fatigue can be analyzed, the method has relatively high precision and operation efficiency, and theoretical support is provided for reliability analysis and optimization of turbine blades.

The invention discloses a wind generating set transmission chain fatigue load prediction method and system considering sandstorm characteristics, and belongs to the technical field of wind power generation and structure fatigue prediction. According to the method, a wind speed time sequence capable of representing sandstorm evolution characteristics is obtained and serves as external physical excitation to be input into a wind-machine-electricity coupling state space model, and a dynamic torque time sequence of a transmission chain low-speed shaft is obtained through calculation; on the basis, a load spectrum is generated by adopting a rain flow counting method, and the accumulated fatigue damage degree corresponding to the sandstorm event is calculated in combination with the Miner linear accumulated damage criterion and the S-N curve of the low-speed shaft material; and further comparing the damage degree with a preset threshold value, and when the damage degree exceeds the threshold value, automatically generating a preventive active load reduction control strategy aiming at the sandstorm, thereby realizing a closed loop of prediction and control. According to the method, the influence of extreme non-stable wind conditions such as sandstorm and the like on the fatigue damage of the transmission chain can be quantitatively evaluated, and technical support is provided for safe operation and predictive maintenance of a wind turbine generator in extreme weather.

The invention discloses a wind power plant active yaw optimization method and system considering a fatigue load of a wind turbine, and relates to the technical field of wind turbine power generation, and the method comprises the steps: obtaining a wake flow model for calculating the equivalent inflow wind speed of a wind wheel surface of the wind turbine; determining a wind wheel surface equivalent inflow wind speed-yaw angle-thrust coefficient two-dimensional lookup table and a wind wheel surface equivalent inflow wind speed-yaw angle-power two-dimensional lookup table of each wind turbine in the wind power plant; constructing an equivalent fatigue load proxy model of the wind turbine based on a blade aerodynamic load and blade gravity coupling effect; and constructing an optimized objective function by taking power maximization and equivalent fatigue load minimization as objectives, solving the optimized objective function through an optimization algorithm according to the actually measured wind turbine-wind measurement data, the wake flow model, each two-dimensional query table and the equivalent fatigue load proxy model, and determining a target yaw angle combination. On the basis of the scheme, the fatigue load caused by the wake effect is reduced while the power improvement is guaranteed, and the active yaw optimization reliability is improved on the whole.

The invention belongs to the field of airplane strength fatigue life prediction, and particularly relates to an equivalent stress-based airplane typical structure multi-axial fatigue life prediction method. The method comprises the steps of determining a typical aircraft high-lock connection structure test piece; determining a fatigue load spectrum; constructing a finite element model of the typical high-lock connection structure of the aircraft; determining a dangerous part of the airplane typical high-lock connection structure test piece in finite element analysis; determining the maximum principal stress at the dangerous part of the typical airplane high-lock connection structure test piece in finite element analysis; determining the fatigue life of the test piece; fitting S-N curve data under different stress ratios according to the fatigue life of the test piece and the load spectrum stress ratio, and determining a corrected S-N curve; determining an equivalent stress-life equation of the typical high-lock connection structure of the aircraft, and substituting the maximum principal stress and fitting parameters of the corrected S-N curve into the equivalent stress-life equation to calculate and obtain a fatigue prediction life; and correcting the fatigue prediction life according to a test result.

The invention provides a wind power blade girder layering damage failure analysis method based on body-shell coupling. The method comprises the steps that a full-size blade geometric model and a full-size blade shell finite element analysis model are established; selecting a full-size blade from a blade root pitch circle to a 1 / 3 blade length section as a shell analysis model; embedding the prefabricated layered defect into the full-size blade girder area by adopting a body-shell coupling method to obtain a body-shell coupling model for blade girder damage failure analysis; blade root fixing constraint is adopted, equivalent fatigue load is applied to the end of the shell analysis model through a multi-point constraint method, out-of-plane displacement of the center point of the upper surface of a sub-plate and the center point of the lower surface of the sub-plate is extracted, and a layered expansion failure process along with load action time is extracted; and carrying out layering failure research on the layering damage of the full-size blade. The method can solve the problem that there is no effective analysis method for the main beam layering failure mode and the expansion path of the wind power blade.

The invention relates to a fatigue limit rapid prediction method based on infrared thermal image energy dissipation characteristics. The method comprises the steps of sample preparation and pretreatment, fatigue loading stress level upper limit determination, infrared fatigue test and temperature rise data acquisition, thermal image data processing and temperature rise feature extraction, energy dissipation model construction, fatigue limit value prediction, error analysis and method verification. The method comprises the following steps: monitoring steady-state temperature rise rates under different stresses through a thermal infrared imager, establishing a relation curve between a dissipation rate and a stress amplitude, predicting a fatigue limit based on a least square method, and comparing the fatigue limit with an S-N test result for verification. Compared with a traditional method, the method has the advantages of high prediction precision, high response sensitivity, low loss, short test period and the like, and is particularly suitable for rapid fatigue limit prediction and strengthening effect judgment of the high-temperature alloy material subjected to laser-assisted ultrasonic rolling strengthening.

The invention discloses a vibration and conventional fatigue load coupled nonlinear damage accumulation prediction method. The method comprises the following steps: analyzing and determining a peak stress at a dangerous point under the loading of a conventional fatigue load according to a finite element model of an engineering component; determining a stress amplitude probability density function at the dangerous point under random vibration loading according to structural dynamics analysis; searching a pre-generated material fatigue life curve; determining equivalent stress at the dangerous point under random vibration loading according to the fatigue life curve; calculating the ratio of the peak stress loaded by the conventional fatigue load at the dangerous point to the random vibration equivalent stress, and establishing a coupling damage parameter according to the vibration and conventional fatigue load coupling series; and establishing a nonlinear damage accumulation model of vibration and conventional fatigue load coupling. According to the nonlinear damage accumulation model provided by the invention, the influence of vibration, a conventional load sequence and a coupling series is considered, the parameter determination is simple, and high-precision prediction of structural damage evolution under complex load coupling can be realized.

The invention relates to the technical field of gearbox fatigue analysis, in particular to a gearbox fatigue analysis method and system. The method comprises the following steps: monitoring vibration data of a gearbox of a wind driven generator through a vibration sensor, firstly extracting an abnormal vibration state and carrying out frequency domain structure analysis to obtain abnormal vibration frequency domain structure data; then, based on the frequency domain data, fractional frequency multiplication sudden change intensity analysis is carried out, side frequency band sudden change intensity data are obtained, and the fatigue load of the gearbox is simulated and quantified through the data; then, feature learning is carried out by utilizing fatigue load data, and a gearbox fatigue analysis model is constructed based on a decision tree algorithm; and finally, sending the model to a terminal so as to execute the fatigue analysis method. According to the method, the gearbox fatigue analysis technology is optimized, so that the gearbox fatigue analysis technology is more perfect.

The invention provides a self-adaptive double-entropy-multi-scale Transform unsupervised cross-domain composite material damage prediction method, which comprises the following steps: preprocessing an acoustic emission signal and extracting a double-entropy feature matrix based on the acoustic emission signal acquired by a composite material test piece under a tensile-tensile fatigue load; constructing a data set based on the double-entropy feature matrix and training a damage evolution model; and inputting the double-entropy feature matrix corresponding to an acoustic emission signal into the trained damage evolution model based on the acoustic emission signal acquired by the composite material test piece under the shear fatigue load, so as to realize real-time prediction of the shear fatigue damage. According to the method, the cross-load high-reliability prediction is realized, the feature dimension redundancy is improved, the physical interpretability is improved, the supervision marking cost is reduced, and a brand new solution is provided for engineering application.

The invention discloses a method for evaluating a fatigue weak area of a welded joint based on crystal plasticity, which aims at the problem of fatigue failure of the welded joint caused by complex microstructures such as grain orientation difference and uneven grain size distribution, establishes a quantitative correlation model of grain orientation and size evolution through CPFEM, and combines a macro-micro cross-scale analysis method to evaluate the fatigue weak area of the welded joint. And precise prediction of local stress concentration and crack initiation behaviors of the welding joint under a real fatigue load working condition is realized, so that scientific evaluation of a fatigue weak region is completed. According to the method, an innovative framework of fatigue weak area evaluation is constructed through load working condition reduction and grain characteristic multi-scale coupling, so that excessive simplification of a traditional method on real load conditions is made up, the limitation that a traditional model is difficult to couple a microstructure and a real load is overcome, and the fatigue weakening quantization precision is remarkably improved; and a high-precision analysis technology is provided for anti-fatigue design, process optimization and service life evaluation of the engineering welding structure.

The invention relates to a blade root fatigue load prediction and inversion system for an offshore wind turbine, and the system comprises a data collection assembly which obtains a circumferential strain gradient, and synchronously collects wave spectrum energy distribution, leading edge erosion degree and three-dimensional wind field data to establish a joint input spectrum; the hybrid calculation component is used for generating an adversarial network, reconstructing strain distribution of a bolt hole in a non-degraded state, and comparing a circumferential strain gradient to obtain an abnormal blade root dangerous point; and the control output assembly is used for superposing the damage accumulation cloud picture of the blade root dangerous point, displaying the fatigue life consumption rate and calling an equivalent load spectrum duration curve, and generating an independent variable pitch angle instruction according to the combination of asymmetric load distribution and the combined input spectrum. According to the method, quantitative identification and positioning of early-stage micro-damage can be realized, the hysteresis limitation of traditional threshold alarm is broken through, complex fatigue analysis is converted into engineering interpretable indexes, and a fault backtracking technical support is provided; load active compensation control is achieved through an independent variable pitch instruction, and fatigue crack initiation and expansion are effectively restrained.

The invention discloses a wind turbine generator adaptive load shedding optimization control method and related equipment. The method comprises the steps of generating three-dimensional turbulent wind field data based on structure parameters and standard wind regime parameters of a wind turbine generator; carrying out aeroelastic coupling simulation based on the three-dimensional turbulent wind field data to obtain a load time sequence of each part under different working conditions, and determining a key part and a dominant load characteristic of the key part; taking the load time sequence of the key part and the reverse slope of the material as input, and calculating an equivalent fatigue load of the key part by using a rain flow counting method; according to the equivalent fatigue load, sensitivity of the key part to wind speed and turbulence intensity is analyzed, a sensitivity result of the key part is obtained, a sensitivity weight in a target function is set according to the sensitivity result, and a sparrow search algorithm is adopted to carry out parameter optimization on a PID controller; and the optimized PID controller is utilized to realize self-adaptive load shedding of the wind turbine generator under the complex working condition. According to the invention, load reduction optimization can be effectively realized.

The invention discloses a surrounding rock damage data analysis system and method based on multiple factors, and relates to the technical field of surrounding rock damage data simulation. A to-be-tested rock material is selected to prefabricate a closed crack group to form a stable roadway; setting different fatigue load intensities and cycle times, analyzing data changes of a stress field, a displacement field and acoustic emission under the action of the fatigue load based on an acoustic emission monitoring system, and determining a bearing performance change model; and real working conditions are simulated based on the bearing performance change model, a difference value between simulated data and real data is formed, an output target of fatigue load strength is intelligently corrected, and data compensation is realized for the bearing performance change model. According to the method, original defects such as joints and cracks in the rock mass and damage evolution under cyclic loads are included into an analysis framework, a reliable basis is provided for long-term safety and stability judgment of a roadway under cyclic load working conditions such as compressed air energy storage, and safe and efficient production of a coal mine is effectively supported.

The invention provides a parallel steel wire corrosion fatigue test device, and relates to the technical field of steel wire physical tests, the parallel steel wire corrosion fatigue test device comprises a closed cylinder, two ends of the closed cylinder are provided with openings for a test steel wire to penetrate, and the two ends of the test steel wire penetrate out of the closed cylinder and then are respectively clamped and fixed with an upper chuck and a lower chuck of a fatigue testing machine; the inner pipe is arranged in the closed cylinder, the test steel wire penetrates through the inner pipe in the axial direction, and the inner pipe is provided with a plurality of cracks with different sizes and / or different forms in the axial direction; the bag body is arranged on the inner wall of the inner pipe, the bag body has a first state and a second state which can be switched, and the aerial fog assembly communicates with the closed cylinder and is used for introducing corrosive aerial fog into the closed cylinder. And a corrosion medium and a fatigue load are synchronously applied to the local area to realize a real-time coupling effect of the corrosion medium and the fatigue load, so that corrosion fatigue test data with higher engineering authenticity and representativeness are obtained.

The invention relates to the technical field of fatigue load reduction, in particular to a wind power plant torque and variable pitch cooperative control method with fatigue load reduction as the target. The method comprises the following steps: acquiring real-time and historical operation data of each fan in a wind power plant, and preprocessing the operation data; based on the preprocessed operation data, load characteristic indexes reflecting structural fatigue are extracted, and a load state vector reflecting the current fatigue accumulation trend of the draught fan is constructed; and based on the load state vector, establishing a coupling model of the influence of the generator torque and the variable pitch angle on the rotating speed response and the fatigue load, wherein the coupling model is used for reflecting the influence mechanism of torque adjustment on the low-frequency load and the inhibition effect of variable pitch adjustment on the high-frequency load. According to the method, the load state vector fusing the low-frequency mechanical load and the high-frequency pneumatic excitation is constructed, and the rain flow counting and equivalent damage theory is combined, so that the load component which has the greatest influence on the fatigue life of key parts such as a main shaft, a transmission chain, a tower and a blade root is accurately identified.

The invention discloses a method for predicting fatigue life of a high-temperature alloy electron beam welding joint by considering residual stress, which comprises the following steps of: on the basis of a traditional S-N curve of the welding joint, superposing the residual stress, and considering that the residual stress is released along with a fatigue load cycle number so as to correct the S-N curve. Firstly, a change curve of the residual stress attenuation rate Sr along with the cycle index in the fatigue loading process of the high-temperature alloy electron beam welding head is established, and a residual stress reduction coefficient K is obtained through calculation based on the Sr curve. The initial residual stress is corrected by introducing a reduction coefficient K, and the initial residual stress and external load stress are linearly superposed to establish a damage parameter, so that a welded joint fatigue life prediction model considering residual stress release is established. The model has relatively high life prediction precision, and compared with the mode that residual stress is not considered, the life prediction dispersion zone is improved from + / -3 times to + / -1.25 times.

The invention discloses a quantitative test method and system for a peak locked-rotor torque of a robot joint module, and relates to the technical field of robot joint performance evaluation, and the method comprises the steps: extracting a torque time-calendar curve of the joint module, defining the peak locked-rotor torque as a controlled low-frequency fatigue loading process, and building a mapping model of a torque amplitude and a failure cycle index; constructing a test system, and performing torque-current static calibration; embedding a specific excitation function in a current loop of the servo driver; the bus voltage and rotating speed change rate is monitored in real time, and the voltage and current impact at the unloading moment is inhibited by adopting a back electromotive force compensation algorithm and combining an energy consumption discharge loop; and repeatedly loading until the structure is damaged, recording the number of cycles, and drawing a peak torque-life curve as a basis for predicting the life of the whole machine. According to the method, quantitative association of the peak locked-rotor torque and the fatigue life is realized, quantitative evaluation from a static index to a dynamic life is realized, a basis is provided for life prediction of the whole robot, and the test precision is improved.

The invention relates to the technical field of buried cracks, in particular to a method, a device, equipment and a medium for evaluating the service life of a dissimilar steel pipeline containing buried cracks, and the method comprises the following steps: calculating service stress; the load ratio and the fracture ratio of the dissimilar steel pipeline are calculated, and whether buried cracks are within an acceptable range or not is judged; if the buried crack is in an acceptable range, predicting the residual life of the creep crack extending to the critical depth; calculating a crack propagation increment under the fatigue load according to a preset fatigue cycle period and an internal pressure fluctuation range; based on the crack propagation increment coupling creep and fatigue propagation amount, determining the propagation amount of the total crack, and determining the creep-fatigue coupling life according to the propagation amount of the total crack; the creep dominant life and the creep-fatigue coupling life are compared to generate a final remaining life for the dissimilar steel pipe. Therefore, the defect that a traditional single-mechanism model is insufficient in response to material mismatch characteristics is overcome, and the problem of crack morphology prediction distortion caused by anisotropy of dissimilar steel materials is solved.

The present application belongs to the technical field of aircraft structure fatigue strength, and particularly relates to a method for converting a buffeting frequency spectrum of an aircraft structure into a fatigue load spectrum, comprising the following steps: Step 1: processing buffeting response load data of the aircraft structure to obtain a first-order bending modal characteristic frequency f1; Step 2: performing narrowband filtering on the buffeting response load data, and calculating a root mean square value σ of the filtered narrowband buffeting response load data; Step 3: performing rainflow counting on the filtered narrowband buffeting response load data to count the amplitude distribution of the narrowband buffeting response load data; fitting the amplitude distribution of the narrowband buffeting response load data with a Rayleigh distribution; and equivalently distributing the amplitude distribution fitted with the Rayleigh distribution to three typical load amplitudes; and Step 4: establishing a periodic step load spectrum according to the frequency of the three equivalent typical load amplitudes.