67 results about "Fatigue stress" patented technology

The invention provides a bridge structure monitoring system and method combined with active early warning, and the method comprises the steps: obtaining dynamic stress data and static stress data of each bridge monitoring point in a bridge section, and constructing a plurality of fatigue stress spectrums according to the dynamic stress data of each bridge monitoring point; determining a damage accumulation coefficient of a bridge structure at each bridge monitoring point according to a stress distribution difference between the fatigue stress spectrums, and extracting a plurality of monitoring key points by combining all the damage accumulation coefficients with dead load characteristics of a bridge section; determining the rigidity of the bridge structure corresponding to each monitoring key point according to the static stress data of each monitoring key point, and determining a confidence interval for performing active early warning on the structural damage of the bridge section according to all the rigidity of the bridge structure; and performing structural damage early warning on the bridge section based on the confidence interval and the current bridge stress at each bridge monitoring point. Accurate early warning of bridge structure damage can be realized under the influence of multi-dimensional load response.

The invention belongs to the field of mechanical performance testing, and relates to an intelligent testing method for the fatigue performance of a wet brake, which comprises the following steps of: acquiring real-time operation data of the wet brake under the condition that a load is applied by a loading device in a testing process by deploying a multi-source monitoring array; generating a fatigue stress distribution diagram representing the stress state of a preset test area of the wet brake based on working condition fusion analysis, correspondingly identifying a failure early warning signal representing the current fatigue damage stage so as to dynamically adjust the parameters of a loading device, and adjusting the stress state of the wet brake in the loading intermittent period of a single test cycle period. The fatigue performance response effect of the wet brake under the action of the current loading strategy is analyzed, the correction direction of the loading strategy of a secondary test cycle is determined, test convergence is achieved through iterative optimization, the consistency of a test result and a real fatigue damage rule is improved, meanwhile, the test efficiency and evaluation precision are improved through closed-loop regulation and control and a self-adaptive iterative framework, and the test accuracy is improved. And a reliable basis is provided for fatigue performance evaluation of the wet brake.

The invention discloses a nonparametric prediction method for the fatigue life of a steel-FRP composite bar, and belongs to the field of fatigue performance evaluation of civil engineering materials and structures, and the nonparametric prediction method comprises the following steps: initializing component material attributes, load conditions and initial states of the steel-FRP composite bar, the component materials comprising an inner core steel bar and an FRP layer; according to an equivalent stiffness distribution principle, fatigue stresses of the component materials are calculated respectively; according to the fatigue stress of the component material, theoretical fatigue life of the component material is obtained in combination with the S-N curve relation, and cyclic jumping is executed; calculating accumulated fatigue damage of the component materials respectively based on results after cyclic jumping; and circularly updating the dynamic stiffness and the equivalent cycle number of the component material until the accumulated fatigue damage of any component material reaches a critical threshold value, judging that the component material is invalid, and outputting the fatigue life. According to the method, the fatigue life of the steel-FRP composite rib can be efficiently and accurately predicted, and the test cost is remarkably reduced.

The invention provides a passenger car body fatigue life prediction and early warning method fusing visual and frequency domain data. The method comprises the following steps: synchronously acquiring a car body vibration time domain signal and a road surface image; converting the time domain signal into a power spectral density curve, extracting frequency domain features, and combining image visual features to jointly identify the grade of the road surface; constructing and dynamically calibrating a digital twin simulation model based on the curve; fusing physical, frequency domain, virtual, visual and knowledge data, and predicting the residual fatigue life through a neural network; on the basis of the power spectral density curve, calculating equivalent fatigue stress through a Miller criterion to carry out fatigue evaluation, and calculating maximum quasi-static stress according to a criterion 3 to carry out static strength evaluation; and dynamically triggering and managing monitoring, early warning and emergency three-level closed-loop early warning according to the road grade, the fatigue damage value and the stress intensity ratio. Accurate sensing of working conditions, fatigue-strength collaborative evaluation and multi-stage dynamic early warning are realized, and the accuracy and practicability of passenger car body safety monitoring are improved.

The invention belongs to the field of corrosion fatigue performance, and particularly discloses a milling workpiece corrosion fatigue life prediction model construction method and a process parameter optimization method.The milling workpiece corrosion fatigue life prediction model construction method comprises the steps that a surface quality prediction model is constructed based on process parameters and corresponding workpiece surface states obtained through tests, and the workpiece surface states comprise surface roughness and hardness; introducing a fatigue stress concentration factor and a work hardening ratio into the initial fatigue life model to respectively reflect local stress concentration caused by surface topography and machining surface hardening caused by milling, and performing surface roughness correction and surface hardness correction on the initial fatigue life model; obtaining a fatigue life model related to the surface state of the workpiece and the corresponding corrosion fatigue life; and combining the surface quality prediction model and the fatigue life model to form a corrosion fatigue life prediction model of the milling workpiece. According to the method, corrosion fatigue life prediction and process parameter optimization of the nickel-aluminum bronze milling workpiece can be realized, and important guidance is provided for actual processing.

A method for predicting and evaluating the fatigue aging damage of austenitic stainless steel is provided. Based on the Allometricl model calculation method, the fatigue stress-fatigue life relationship corresponding to the low-cycle accelerated fatigue experiment is output, and the coincidence degree is evaluated by establishing the fitting relationship between the stress amplitude and the fatigue life using the Basquin formula; based on the KAM value in EBSD as the characteristic defect parameter, the change curve with the number of cycles is calculated; based on the Vickers hardness as the mechanical characteristic parameter, the fitting relationship between the Vickers hardness and KAM of each stage sample of the fatigue sample under the fatigue stress is obtained; based on the correlation model between the KAM value and the saturation magnetic induction intensity, the fitting relationship between the saturation magnetization intensity and KAM of each stage sample of the fatigue under the stress action is obtained. By combining the evolution of micro-defects and the macroscopic magnetic properties, the present application realizes the in-situ non-destructive detection and life evaluation of the austenitic stainless steel structure, providing a new technical means for the reliability analysis of engineering structures.

According to the electromagnetic reversing valve, the structure of the electromagnetic reversing valve is optimally designed, the concave part is additionally arranged on the transition part of the valve body part, and / or the convex part is arranged on the first plate-shaped part of the valve body part, so that stress generated when a high-temperature and high-pressure medium enters the valve body part is dispersed, fatigue stress generated by the valve body in a high-pressure environment is effectively weakened, and the reliability of the electromagnetic reversing valve is improved.

This invention discloses a stress gradient absorbing, self-toughening, high-load-bearing phosphogypsum pavement structure, relating to the field of road construction materials technology. From top to bottom, it comprises a high-strength load-bearing layer, a stress transmission layer, and a stress dispersion layer. The raw materials for the high-strength load-bearing layer, stress transmission layer, and stress dispersion layer include modified phosphogypsum, cement, admixtures, a complexing water-resistant crosslinking agent, a water-reducing agent, and water. The modified phosphogypsum is prepared by adjusting the pH value of phosphogypsum waste to 7-8. The admixtures are blast furnace slag and / or metakaolin. The pavement structure provided by this invention achieves improved base layer strength and modulus, as well as gradient distribution, effectively transferring pavement stress to the underlying layer while reducing fatigue stress in the base layer material and increasing the fatigue life of the pavement base layer.

The invention relates to a movable flap (16) for the leading edge of an aircraft wing, the flap being intended to be mounted on a fixed part (8) of the wing and comprising two flap ends (16a, 16b) positioned opposite one another along the span (17) of the flap, the flap defining a leading edge zone from which a lower surface and an upper surface extend, the surfaces being spaced apart from one another over the height (21) of the flap. According to the invention, the flap has a generally upwardly concave shape in its nominal state in order to limit fatigue stresses on the flap during flight.

The present application relates to a kind of method, device and electronic equipment for predicting GFRP-RC beam fatigue life, method includes: obtaining the limit bearing capacity before the destruction of GFRP-RC beam and the maximum deflection before the destruction of the GFRP-RC beam, the limit bearing capacity and the maximum deflection are by the GFRP-RC beam is obtained by three-point bending static loading test, obtain the initial fatigue deflection value of the GFRP-RC beam, the initial fatigue deflection value is by the GFRP-RC beam is carried out fatigue stress level cyclic loading test, and the test result is carried out initial deflection identification and obtains, based on the maximum deflection and the initial fatigue deflection value, input to the preset CEB-FIP fatigue life prediction model, obtain the GFRP-RC beam fatigue life.

The invention provides a ballastless track concrete dynamic fatigue life prediction method and system, and relates to the technical field of high speed railway ballastless track performance evaluation.The method comprises the steps that a load spectrum of a ballastless track is obtained, and the load spectrum comprises a train dynamic load spectrum and an environment temperature change spectrum; based on the load spectrum, a fatigue stress spectrum of the track slab is calculated through a track fatigue stress calculation model, and the fatigue stress spectrum comprises a stress amplitude, a stress base value and an action frequency; dividing stress grades according to the fatigue stress spectrum, determining stress parameters of each grade in combination with concrete tension and compression characteristics, and calling a corrected fatigue life equation to calculate the fatigue life under the current stress grade; based on the fatigue life, a damage variable increment is calculated through a nonlinear damage accumulation criterion, and a total damage variable is obtained through accumulation; and judging a fatigue failure state according to the total damage variable, and if the fatigue failure state does not occur, updating material parameters and carrying out iterative calculation until the fatigue failure is judged.

The application discloses a method and device for testing coating performance of an engine hot-end component, and the method comprises the following steps: obtaining working condition data of an engine, wherein the working condition data comprises task profile data, simulation data and measured data of the engine; establishing a temperature model, a corrosion load model and a fatigue stress model based on the working condition data; determining an environment spectrum of the engine based on the working condition data, the temperature model, the corrosion load model and the fatigue stress model, wherein the environment spectrum comprises a time sequence of multiple working conditions of the engine and corresponding environment test parameters in the multiple working conditions; and testing a coating sample of the engine based on the environment spectrum to obtain a test result of the coating sample. The application establishes a mapping relationship between test environment parameters and actual working conditions, and overcomes the simulation distortion problem caused by using fixed environment parameters for testing in the prior art.

The utility model relates to a CFRP reinforcing device for a fatigue crack of a steel bridge. The steel bridge fatigue crack CFRP reinforcing device relates to the technical field of steel bridge fatigue cracks. The CFRP reinforcing device for the fatigue crack of the steel bridge comprises telescopic shells, telescopic blocks and deformed steel bars, the telescopic shells and the telescopic blocks are symmetrically arranged, the situation that new cracks appear on a steel member is reduced by means of high temperature resistance, mechanical stability and small thermal expansion coefficient of CFRP plates, the CFRP plates are of a Z-shaped plate-shaped structure bent back and forth, the number of the CFRP plates is two, and the number of the CFRP plates is two. The two CFRP plates are arranged between the telescopic shells and the telescopic blocks correspondingly, so that when the two telescopic shells are pulled by stress, the CFRP plates are compressed and released, the stress pulling effect is further reduced, the connection stability between the steel members is improved, fatigue stress is well reduced, and new cracks are reduced.

The utility model provides a kind of high mileage all-steel load radial tire tread pattern suitable for full wheel position and tire, the design of the pattern groove of the present application can prevent the pattern groove from clamping stone, and can effectively reduce the damage of groove bottom crack caused by groove bottom fatigue stress;The design of U-shaped groove improves the drainage property while ensuring the self-cleaning performance of the tire;Moreover, the angle of the normal direction of the sidewall of the central pattern groove and the sidewall above the tread is the same, which can also make the stress on both sides of the entire tread pattern more uniform.

The invention discloses an engine hot end component coating performance testing method and device, and the method comprises the steps: obtaining the working condition data of an engine, and the working condition data comprises the mission profile data, simulation data and actual measurement data of the engine; establishing a temperature model, a corrosion load model and a fatigue stress model based on the working condition data; based on the working condition data, the temperature model, the corrosion load model and the fatigue stress model, an environment spectrum of the engine is determined, and the environment spectrum comprises time sequences of multiple working conditions of the engine and environment test parameters corresponding to the multiple working conditions; and testing the coating sample of the engine based on the environment spectrum to obtain a test result of the coating sample. By establishing the mapping relation between the test environment parameters and the actual working conditions, the problem of simulation distortion caused by adopting fixed environment parameters for testing in the prior art is solved.

The invention relates to the technical field of single crystal alloy fatigue life prediction, in particular to a nickel-based single crystal alloy fatigue life prediction method considering second orientation and recrystallization defects. The specific method comprises the following steps: obtaining a plurality of nickel-based single crystal alloys as single crystal alloy samples which have different second orientations and have recrystallization defects partially; establishing a crystal plastic model; acquiring fatigue life and fatigue stress parameters; inputting the fatigue stress parameter into a crystal plastic model to calculate the accumulated plastic shear strain of the dangerous point; 1 / 2 of the product of the cumulative plastic cutting strain and the fatigue load in the crystal plasticity or the cumulative plastic cutting strain is used as a fatigue indication factor; and fitting by taking the fatigue indication factor as a vertical coordinate and the fatigue life as a horizontal coordinate to obtain a fatigue life prediction model. According to the method, the recrystallization defect and the influence of different second orientations are considered, the related fatigue indication factors are introduced to construct the fatigue life prediction model between the fatigue indication factors and the fatigue life, and the accuracy and reliability of the prediction result are improved.

The present invention relates to a steel strand with excellent fatigue resistance and a production method thereof. By making full use of existing equipment conditions, optimizing the ratio of alloy elements, and combining the following production methods, including heating in a heating furnace, continuous rolling on multiple stands, cooling by flow control in different water tanks after finish rolling, Stelmor phase transformation cooling, coiling to form wire rods, drawing the wire rods and twisting the steel wires to form steel strands, and stabilizing and coiling the steel strands, the plasticity of the wire rods is improved under the existing production level, and the residual stress state of the steel wire is improved to increase the fatigue stress amplitude of the steel strand, thereby meeting the high stress amplitude fatigue requirement of 2000MPa-grade steel strands.

The present invention provides a method and system for calculating the fatigue life of a prefabricated box culvert on a road, relating to the fields of material mechanics and civil engineering technology. The method establishes a three-dimensional finite element model of the box culvert, screens fatigue hotspots, and, based on fatigue stress analysis, installs strain sensors at the fatigue hotspots to measure stress values. Calibration coefficients are generated using vehicle weight and speed data to correct the stress values. Temperature sensors are deployed for real-time monitoring, and a temperature compensation model is established to correct the stress data. Ultimately, after calibration and compensation, the true stress values of the fatigue hotspots are obtained, the cumulative damage degree is defined, and the fatigue life of each hotspot is calculated based on Miner's law. By establishing a three-dimensional finite element model and implementing stress and temperature monitoring and calibration, the present invention accurately assesses the fatigue performance and service life of the box culvert.

The invention discloses a fatigue simulation method for local stress ratio change caused by nonlinear deformation, and belongs to the technical field of composite material fatigue performance research. The method comprises the following steps: determining a fatigue load peak-valley value and calculating a fatigue stress ratio; the fatigue loading process is divided into two stages; calculating the equivalent fatigue life under the current fatigue cyclic loading; calculating a stress ratio under current fatigue cyclic loading; calculating the equivalent fatigue life of the current unit; establishing a uniaxial fatigue rigidity degradation model and a uniaxial fatigue strength degradation model of the composite material, and calculating the overall fatigue life of the models. By considering the influence of local stress ratio change on the fatigue life of the composite material in the fatigue process and based on the equal-life model, the rigidity degradation model, the strength degradation model and the fatigue failure criterion, a more accurate composite material fatigue simulation analysis method is established, the prediction precision of a traditional model is optimized, and the prediction efficiency is improved. And the blank in the field of composite material fatigue simulation calculation is filled.

The invention relates to the technical field of testing devices, and provides a fatigue life testing device for a pipe, the fatigue life testing device comprises a vibration table, a first connecting mechanism and a second connecting mechanism, the vibration table comprises a base and a working platform, and the vibration table enables the working platform to at least output disturbance force of which the amplitude changes randomly; the first connecting mechanism is arranged on the working platform, and the first connecting mechanism is connected with the first end of the pipe to be tested; the second connecting mechanism is arranged on the base and connected with the second end of the pipe to be tested. Through the arrangement, the to-be-tested pipe is connected through the first connecting mechanism and the second connecting mechanism, the vibrating table can be used for applying disturbing force within a preset amplitude range to the to-be-tested pipe, and the amplitude of the disturbing force randomly changes within the preset amplitude range; therefore, the fatigue stress suffered by the pipe to be tested in the rocket launching process can be effectively simulated, and the fatigue life of the pipe for connecting the two parts of the spatial load in the rocket launching process can be accurately measured.

The invention provides a pavement structure analysis method, electronic equipment and a medium, and the pavement structure analysis method comprises the following steps: adjusting the type of each structural layer of a pavement and / or the thickness of each structural layer of the pavement, so that the pavement structure meets the requirements of a pavement structure design limit state equation; a method for calculating the accumulated axle load action times based on designed axle loads such as double axles and single axles is established, and a basis is provided for road pavement structure design under different load conditions. The load fatigue stress is calculated according to single-axis, double-axis and other designed load axes under different load conditions, the load fatigue stress calculation result is more accurate, the method can be suitable for pavement structure design under different load conditions, and pavement load characteristics and engineering requirements are better reflected and met.

The application provides a bridge structure monitoring system and method combined with active early warning, dynamic stress data and static stress data of each bridge monitoring point in a bridge section are acquired, a plurality of fatigue stress spectra are constructed according to the dynamic stress data at each bridge monitoring point, a damage accumulation coefficient of the bridge structure at each bridge monitoring point is determined according to the stress distribution difference between the fatigue stress spectra, a plurality of monitoring key points are extracted by combining all the damage accumulation coefficients with the dead load characteristics of the bridge section, the bridge structure stiffness corresponding to each monitoring key point is determined by the static stress data of each monitoring key point, a confidence interval for active early warning of the structural damage of the bridge section is determined by all the bridge structure stiffnesses, and the structural damage of the bridge section is early warned based on the confidence interval and the current bridge stress at each bridge monitoring point. The application can realize accurate early warning of the bridge structure damage under the influence of multi-dimensional load response.

The invention provides a nuclear power plant main loop vibration monitoring method and system based on modal analysis, and the method comprises the steps: extracting main and local modal parameters covering target percentage modal participation quality through modal analysis, dividing a characteristic frequency band according to a dominant modal frequency, corresponding to a vibration parameter limiting value, and obtaining a vibration parameter; meanwhile, in combination with a modal stress and displacement distribution database of the model, a material fatigue life curve and a local stress concentration factor, accurately determining a vibration displacement limit value and a bending moment limit value of each characteristic frequency band, and then segmenting an original vibration signal by adopting a digital signal processing technology; the method comprises the following steps: obtaining an independent analysis frequency band corresponding to a characteristic frequency band, carrying out dynamic threshold filtering statistics, then comparing a frequency-band actually-measured vibration amplitude with a corresponding limit value in real time, triggering a differential early warning strategy, finally calculating a multi-modal actual distribution stress in combination with an actually-measured vibration value and a modal database, and verifying the multi-modal actual distribution stress with a standard fatigue stress. Accurate control of the vibration risk of the main loop piping system and scientific guarantee of structural safety are achieved.

The application discloses a non-parametric prediction method for fatigue life of steel-FRP composite bars, belonging to the field of fatigue performance evaluation of civil engineering materials and structures, comprising: initializing component material properties, load conditions and initial state of the steel-FRP composite bars, wherein the component materials include inner core steel bars and FRP layers; calculating fatigue stresses of the component materials respectively according to equivalent stiffness distribution principle; obtaining theoretical fatigue lives of the component materials respectively according to the fatigue stresses of the component materials in combination with S-N curve relationship, and performing cycle skipping; calculating cumulative fatigue damages of the component materials respectively based on results after the cycle skipping; and cyclically updating dynamic stiffness and equivalent cycle number of the component materials until the cumulative fatigue damage of any component material reaches a critical threshold value, then determining failure of the component material and outputting the fatigue life. The application can efficiently and accurately predict the fatigue life of the steel-FRP composite bars, and significantly reduce test cost.

The invention relates to a sling corrosion-multi-axial fatigue life prediction method and device. The prediction method comprises the following steps: S10, acquiring key mechanical parameters of a sling under a predetermined load; s20, establishing a layered slip finite element model of the sling based on a layered slip theory, and solving the fatigue stress amplitude of each layer of steel wire of the sling; s30, the minimum fracture life and the corresponding steel wires are determined, and the accumulated damage degree of the remaining steel wires under the minimum fracture life is evaluated; s40, updating the layered slippage finite element model of the remaining steel wires, and determining the corrosion-multi-axial fatigue life of the sling; and S50, acquiring the corrosion-multi-axial fatigue life of the sling in multiple life cycles, and analyzing the probability distribution characteristics of the corrosion-multi-axial fatigue life of the sling. The performance evolution and failure process of the sling under the coupling action of the corrosion environment and the complex stress state can be simulated, and a reference basis is provided for service state evaluation and maintenance decision making of the sling.

The invention provides a method for predicting the service life of molten parts of a laser shock peening laser powder bed, and relates to the technical field of performance evaluation of additive manufacturing parts. Firstly, based on technological parameters of laser shock peening, residual stress distribution from a material surface layer to a set depth is constructed; based on the strain coordination relation, a relaxation model of residual stress with cyclic loading is established, and equivalent residual stress is calculated through the coupling effect of the external load and the residual stress; then determining a theoretical stress concentration coefficient Kt and a fatigue stress concentration coefficient Kf according to the size, the shape and the position of a defect in the LPBF part; the effective residual stress, the external load, the fatigue stress concentration coefficient and the material fatigue parameter are jointly introduced into a life prediction model, and the fatigue life is calculated; and outputting fatigue life prediction values of the parts under different LSP parameters and load conditions for process selection and structure design.

The invention relates to the technical field of fatigue pressure monitoring, and discloses a non-inductive fatigue pressure dynamic tracking system based on optical fiber sensing, which comprises a flexible optical fiber sensing array, a signal demodulation module, a data processing unit and an output unit, the flexible optical fiber sensing array is used for collecting a dynamic pressure signal of a monitored object under the action of a load and converting the dynamic pressure signal into an optical signal; and the signal demodulation module. Non-inductive monitoring is achieved through the flexible optical fiber sensing array, the flexible substrate adopts a polyimide film and is attached to the surface of a monitored object without obvious protrusions, constraint of a traditional rigid sensor on deformation of the monitored object is avoided, and temperature interference is separated in combination with a temperature compensation optical fiber; and a dynamic correction module adjusts a fatigue damage calculation weight based on a local stress concentration coefficient, so that the problems of hindering of signal transmission and large local fatigue damage evaluation deviation in traditional monitoring are solved, and the requirements of long-term dynamic tracking on a monitoring mode and evaluation precision are met.

The present application belongs to the field of mechanical performance testing, and relates to an intelligent test method for fatigue performance of a wet brake, which collects real-time operation data of the wet brake under a load applied by a loading device during a test process through deployment of a multi-source monitoring array, generates a fatigue stress distribution map representing a stress state of a preset test region of the wet brake based on working condition fusion analysis, and correspondingly identifies a failure warning signal representing a current fatigue damage stage to dynamically adjust parameters of the loading device, analyzes fatigue performance response effects of the wet brake under a current loading strategy during a loading intermittent period of a single test cycle, determines a correction direction of a loading strategy of a secondary test cycle, iteratively optimizes to achieve test convergence, improves consistency of test results and real fatigue damage rules, and improves test efficiency and evaluation accuracy through a closed-loop control and self-adaptive iteration framework to provide a reliable basis for fatigue performance evaluation of the wet brake.

The invention relates to the technical field of bridge construction, in particular to a steel bridge deck slab welding joint fatigue reliability analysis method and device considering pavement layer temperature time-varying characteristics. The method comprises the following steps: constructing a pavement layer temperature-vehicle-induced stress amplitude correlation model based on pavement material test data; based on the representative sample set of the annual fatigue vehicle load spectrum, the pavement layer temperature time sequence representative sample set and the pavement layer temperature-vehicle-induced stress amplitude correlation model, obtaining a vehicle-induced stress amplitude time sequence representative sample set considering pavement layer temperature time variation; and based on the vehicle-induced stress amplitude time sequence representative sample set considering the pavement layer temperature time variation, obtaining the fatigue reliability of the welding node of the steel bridge deck. The method not only reflects the long-term influence of the pavement layer temperature time-varying characteristic on the fatigue stress of the OSD welding node, but also has relatively high calculation efficiency. The method solves the problems of high calculation cost and time consumption of traditional finite element time-history analysis when long duration structural response calculation is carried out.

The invention provides an anti-fatigue connecting structure suitable for a net rack underslung crane, which is applied to the technical field of suspended cranes, and comprises a net rack ball joint unit, a distribution beam unit and a track beam, the track beam is used for hanging and connecting the crane, and the distribution beam unit is used for distributing the distribution beam unit to the net rack ball joint unit. The net rack ball joint unit comprises a plurality of ball joints which are located on a net rack lower chord layer and distributed on the two sides of the track beam, the upper portion of the distribution beam unit is connected with the ball joints, and the lower portion of the distribution beam unit is connected with the track beam. The distribution beam unit is used for distributing the vertical load of the crane into a plurality of ball nodes distributed on the two transverse sides of the track beam at any running position of the track beam, and comprises a plurality of primary distribution beams which are distributed at intervals in the longitudinal direction of the track beam; by using the anti-fatigue connection structure, the fatigue stress amplitude and the total stress of a single net rack sphere node can be reduced, and the anti-fatigue performance of the node is improved.