206 results about "Fatigue loading" patented technology

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 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 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 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 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 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.

The application discloses a tower fatigue load accumulation method and system based on wind direction frequency distribution, and the method comprises the following steps: S1, acquiring the wind frequency distribution of each sector of a specific site location, the Weibull distribution parameters of each sector and the effective turbulence intensity of each sector; S2, obtaining the equivalent fatigue load corresponding to the tower circumference weld hot spot through load calculation; S3, sorting the wind frequency distribution of each sector and the equivalent fatigue load corresponding to the tower circumference weld hot spot; according to the fatigue curve index m of the material and the sorted parameters, equivalent conversion is performed on the equivalent fatigue load of all sectors to obtain the equivalent maximum value of the tower circumference; and S4, according to the equivalent fatigue load-stress relationship, the equivalent maximum fatigue damage of the tower circumference life cycle is calculated. The application has the advantages of effectively reducing the equivalent fatigue load of the tower weld, reducing the weight of the tower, saving the amount of steel material, reducing the investment cost of the wind power and the like.

The application discloses a component fatigue micro-damage early identification method based on a nonlinear static component, and particularly relates to the technical field of material nondestructive testing and structural health monitoring, which comprises the following steps: arranging an excitation probe and a receiving probe on the surface of a component to be measured; selecting an excitation frequency based on a frequency dispersion curve and generating a Hanning window modulated wave; collecting a propagation response signal; extracting a static component amplitude A and a fundamental wave amplitude A through time-frequency processing; calculating a nonlinear static parameter beta=A / A²; further calculating a first derivative S(N) and a second derivative ΔS(N) of beta with respect to a fatigue loading cycle N; and identifying a dislocation dominant stage, a dislocation saturation or rearrangement stage, a micro-crack initiation stage and a macro-crack formation stage according to the first derivative S(N) and the second derivative ΔS(N). The application can be used for early stage identification of the evolution process of component fatigue micro-damage.

An offshore wind power plant designed to reduce a fatigue load of a wind turbine includes an offshore structure, a plurality of wind turbines which is installed above the offshore structure to be spaced apart from each other with a predetermined distance and is supplied with a power through wind to produce electrical energy; and a turbine controller which controls at least one of a pitch movement and a yaw movement for the plurality of wind turbines.

The utility model provides a fatigue testing device for a rubber-tyred loader, which relates to the field of vehicle testing, and comprises a fixed base, a test bed, a clamping sleeve upper cover, a distribution beam and an actuator, the fixed base is fixed on the test bed, the clamping sleeve upper cover is detachably and fixedly connected with the fixed base, and the distribution beam is fixed on the fixed base. The clamping sleeve and the fixing base define an installation space capable of containing a hub, the hub is arranged in the installation space, and when the clamping sleeve upper cover and the fixing base are fixed in place, the clamping sleeve upper cover and the fixing base can clamp and fix the hub. The actuator is fixed on the test bed, the distribution beam is fixed at the output end of the actuator and detachably fixed on the bucket, and the actuator is used for carrying out fatigue test loading according to a set load spectrum; the clamping sleeve upper cover and the fixing base clamp and fix the hub, circumferential fixation of the hub is achieved, abnormal deformation and displacement of a tire in fatigue loading are replaced, force and displacement of parts such as a frame and a large arm are prevented from being absorbed by the tire, and mechanical analysis and testing of the loading machine are facilitated.

This application discloses a method, apparatus, equipment, medium, and product for predicting damage evolution based on dynamic order reduction, relating to the field of aero-engine health management and monitoring. The method includes: conducting finite element fatigue / creep-fatigue simulation tests on structural components covering stress states under various operating conditions, and extracting the time-physics field matrix from the finite element fatigue simulation results under each operating condition; dynamically reducing the order of the time-physics field matrix to reduce its dimension, obtaining a reduced-order matrix; constructing a reduced-order model; restoring the equivalent stress field distribution based on the reduced-order model to obtain the reduced-order physical field; predicting the damage distribution evolution and fatigue life under fatigue or creep-fatigue loading based on the reduced-order physical field, and making corrections based on the fatigue life prediction model. This application can improve the efficiency and universality of life prediction.

The invention discloses a wind turbine generator transmission chain system fatigue load prediction method and a related device. The method comprises the steps of obtaining a load time sequence of a wind turbine generator transmission chain system; calculating the fatigue load of the wind turbine generator transmission chain system according to the load time sequence of the wind turbine generator transmission chain system; decomposing the fatigue load of the wind turbine generator transmission chain system to obtain a plurality of subsequences; inputting each subsequence into a corresponding model to obtain a plurality of decomposition component predicted values; and integrating the predicted values of the decomposition components to obtain a prediction result of the fatigue load of the transmission chain system of the wind turbine generator, and the method and the related device can accurately predict the fatigue load of the transmission chain system of the wind turbine generator.

The application discloses a kind of three-dimensional weaving ceramic matrix composite fatigue prediction model calculation methods, comprising: by the analysis of SiC / SiC fiber bundle composite fatigue test results, the remaining stiffness degradation law of fiber bundle composite is obtained;Establish the RVE model in line with the microstructure of three-dimensional weaving CMC, and it is carried out periodic grid division and the application of periodic boundary condition;The fiber bundle remaining stiffness degradation model is substituted into three-dimensional weaving CMC RVE model and carries out finite element calculation, and the fatigue life of three-dimensional weaving CMC material under arbitrary peak fatigue cycle load, the remaining stiffness degradation curve is predicted in combination with three-dimensional Hashin failure criterion.This application comprehensively considers the influence of various damage forms of ceramic matrix composite under fatigue load and different temperature environment to SiC / SiC fiber bundle composite material, so that the prediction result can better adapt to actual working environment.

The invention discloses a seaplane wave sliding load spectrum compilation method. The method comprises the steps of determining gravity center acceleration data of pool test data of each task section according to overall and structural parameters of a seaplane; comparing a gravity center acceleration time history curve representing the gravity center acceleration data with an airframe trim angle time history curve, and intercepting stable section data of each task section; performing power spectrum density analysis on acceleration overload / overload increment in the stable section data to obtain an acceleration characteristic frequency band; determining a cut-off frequency according to the acceleration characteristic frequency band, and filtering the stable section data; carrying out accumulated transcendental statistics on the filtered stable section data to obtain an accumulated transcendental curve of each task section; according to the time proportion of each task segment and the similarity criterion, obtaining an accumulative surpassing curve of each task segment of the real machine water surface operation; and forming a body wave sliding equivalent spectrum according to a damage equivalence criterion. The technical problem of compiling and verifying the water skiing fatigue load spectrum of the seaplane is solved.

The invention relates to the technical field of structure testing, in particular to an overhead rigid suspension expansion joint fatigue test device and method, and the device comprises a fatigue host module which provides reciprocating vertical vibration power for an expansion joint; the comprehensive platform module is used for providing reciprocating horizontal vibration power for the fatigue host module; the control system module comprises a strain data processing unit which is used for constructing a three-dimensional strain field model and calculating stress distribution based on the strain data; the phase compensation generation unit dynamically generates lag compensation time of the horizontal vibration relative to the vertical vibration; and the driving control unit is used for adjusting the phase of the horizontal vibration in real time based on the lag compensation time, so that the horizontal vibration reaches the maximum displacement value at the vertical vibration peak moment. According to the invention, the authenticity, accuracy and reliability of the fatigue test of the expansion joint can be effectively improved, the phase and displacement synchronization of horizontal vibration and vertical vibration can be dynamically adjusted through a linkage control mechanism, and the spatial multidirectional composite fatigue load in actual operation can be reproduced.

The utility model discloses a fan blade swing fatigue testing device, and belongs to the technical field of fan blade fatigue testing. Comprising a blade clamping module and a fatigue loading excitation module. The fatigue loading excitation module comprises a plurality of groups of random wooden saddles used for clamping blades in an up-down matching manner, the random wooden saddles comprise upper random wooden saddles and lower random wooden saddles, upper steel plates are arranged at the tops of the upper random wooden saddles, lower steel plates are arranged at the bottoms of the lower random wooden saddles, and the upper steel plates and the lower steel plates are connected through studs; an excitation motor is arranged on the upper steel plate, and the output end of the excitation motor is connected with the eccentric mass block through a rotating arm. The blade fatigue testing device has the advantages of reducing testing energy consumption, improving blade testing efficiency, being suitable for fatigue testing of blades of different sizes, and being low in testing noise.

The utility model discloses a gear fatigue test fixture, which comprises a gear clamping part, a gear tooth loading part and a position adjusting part, and is characterized in that the gear clamping part comprises a gear left supporting plate, a gear right supporting plate, a clamping nut, a clamping bolt and a gear supporting plate fastening bolt; the gear tooth loading part comprises an upper pressure head, a lower pressure head, a lower pressure head height adjusting nut, a lower pressure head sleeve and a lower pressure head sleeve fastening bolt; the position adjusting part comprises a sliding platform, an adjusting lead screw, an adjusting hand wheel, a lead screw cover plate, a sliding platform fastening bolt and a fixed platform. The utility model also discloses a gear fatigue loading machine. According to the utility model, fatigue test requirements of gears with different diameters and different widths can be met.

The utility model discloses a biaxial fatigue test mold which comprises two clamping and loading assemblies, each clamping and loading assembly comprises a threaded sleeve, a sleeve, a deformation block and a clamping sleeve, and the deformation block is placed between the threaded sleeve and the sleeve; a clamping hole channel is formed in the deformation block; the threaded sleeve moves relative to the sleeve by rotating and screwing, and the generated displacement acts on the deformation block, so that the clamping hole channel of the deformation block annularly holds the pipe. One end of the clamping sleeve is connected with the sleeve, the other end of the clamping sleeve is connected with the fatigue machine, an oil injection pipe is arranged on the side face of the clamping sleeve, one end of the oil injection pipe is communicated with a cavity channel of the clamping sleeve, and the other end of the oil injection pipe is connected with an external oil source. And the external and internal parts of the pipe are simultaneously clamped and loaded, so that local high stress concentration generated on the surface of the pipe by a traditional mechanical clamp is reduced, and the accuracy of an experimental result is improved.

The application particularly relates to a cast stainless steel multiaxial low-cycle fatigue prediction method, which comprises the following steps: measuring or calculating the axial strain amplitude and the corresponding axial stress, the shear strain amplitude and the corresponding shear stress, and the phase difference between the axial strain amplitude and the shear strain amplitude of a cast stainless steel concerned part; calculating the equivalent axial strain amplitude and the equivalent shear strain amplitude of the cast stainless steel concerned part after correction and containing the influence of thermal aging; and substituting the equivalent axial strain amplitude and the equivalent shear strain amplitude of the cast stainless steel concerned part after correction and containing the influence of thermal aging and the phase difference therebetween into a cast stainless steel multiaxial low-cycle fatigue prediction model containing the influence of thermal aging to calculate the multiaxial low-cycle fatigue life and the fatigue crack direction of the cast stainless steel after thermal aging. The cast stainless steel multiaxial low-cycle fatigue prediction method can accurately predict the fatigue life of the cast stainless steel under multiaxial low-cycle fatigue loading and the direction of fatigue crack initiation and initial propagation.

The invention discloses a hydraulic fatigue test device and method for a high-pressure hydrogen storage cylinder. The test device comprises an oil tank, a hydraulic power unit, a multi-stage pressurization unit, a hydraulic compensation unit, a detection unit and a control unit, an oil inlet of the hydraulic power unit is connected with the oil tank, and an oil outlet is connected with an inlet of the multi-stage supercharging unit through a first pipeline; an outlet of the multi-stage supercharging unit is connected with an inlet of the hydrogen storage bottle through a second pipeline; an outlet of the hydrogen storage bottle is connected to the oil tank through a third pipeline, and a pressure release valve is arranged on the third pipeline; the accommodating cavity of the hydraulic compensation unit is connected with the second pipeline; the control unit is connected with the hydraulic power unit, the hydraulic compensation unit and the detection unit. According to the invention, the pressure stability of + / -0.15 MPa can be realized, and the high fidelity of the fatigue load waveform is ensured.

The invention provides a discrete ballastless track tension-compression fatigue damage rapid calculation method, which comprises the following steps of: uniformly measuring a complex stress state and a simple stress state through a damage energy release rate, and decomposing tension-compression effective stress by utilizing a fourth-order projection tensor, so that the tension-compression effective stress value is equivalent to a uniaxial tension-compression stress value under a uniaxial loading condition; constructing a hyperbolic function with a natural constant as a base and a damage variable as an index on the basis of the damage energy release rate and in combination with three-stage damage characteristics of high-cycle fatigue of the material; carrying out integration on fatigue loading times through tension and compression damage, and deducing to obtain a discrete transcendental differential function of the damage related to the loading times; function variables are defined, an initial value is set, an iteration format is established, the discrete transcendental differential function is solved through a numerical integration method, and a calculation result graph is drawn. The model is simplified, and the calculation efficiency is improved; a high-order tensor stress updating algorithm does not need to be constructed, redundant calculation is reduced, and the data processing efficiency and the calculation speed during parameter analysis are greatly improved.