41 results about "Stress gradient" patented technology

The invention discloses a fatigue life simulation evaluation method for a lightweight aluminum alloy material of a new energy automobile, and relates to the technical field of material life evaluation. A microstructure image is collected, coupling features are extracted through machine learning, and heterogeneous data fusion and enhancement are completed; generating a topological optimization structure based on a GAN, introducing a VPSC model to describe anisotropy according to a stress gradient dynamic grid, and constructing a dynamic finite element model; fusing vehicle driving data, predicting a load by using LSTM, performing VMD decomposition and environment correction, and realizing space-time correlation load spectrum reconstruction; a phase field model is used in a microcosmic mode, cracks are tracked in a macroscopic mode through XFEM, damage parameters are transmitted in a bidirectional coupling mode, and multi-physics field coupling simulation is carried out; fusing simulation and test data by adopting Bayesian reasoning, calculating life probability distribution, and correcting parameters when errors exceed the limit; according to the method, the fatigue life prediction error is finally reduced, the time consumption of single simulation is reduced, full-life-cycle evaluation and visual early warning are realized, an efficient scheme is provided for lightweight design, and industrial technology upgrading is promoted.

The invention relates to the technical field of machining defect monitoring, and discloses a machining defect real-time positioning and multi-physics field visualization system based on a multi-source track. The system comprises a multi-source trajectory data acquisition module for acquiring a cutter motion trajectory sequence, a temperature distribution sequence and surface topography monitoring data to form a multi-source trajectory data set; the multi-physics field reconstruction module processes the data set to generate defect distribution characteristics containing thermal stress gradient, force distribution cumulant and defect fluctuation coefficient; the defect positioning analysis module calls the pre-training model for real-time analysis and outputs a defect position predicted value and a defect type identifier; the environment compensation correction module corrects a defect position prediction value by combining a temperature distribution sequence and a material thermal characteristic incidence relation; and a visualization strategy generation module generates a multi-physical field visualization strategy set containing thermal field rendering and force field superposition schemes according to the defect type identifier.

The invention belongs to the technical field of industrial detection, and provides a low-temperature fatigue crack propagation life prediction method and system based on a steel bridge deck, and the method comprises the steps: judging whether the crack direction deflection risk assessment needs to be started or not through the sharp reduction of steel plasticity and the non-uniform analysis of local stress gradient; if yes, the crack direction deflection risk of the steel bridge deck is evaluated by analyzing the grain orientation difference and the strengthening phase of the welding seam and the HAZ area; if the risk is high, a stress gradient gentle area is determined through a weld toe stress gradient cloud picture, a resistance-gradient coupling equation is established according to the minimum resistance principle and in combination with the stress gradient, and a crack deflection path is determined; dividing the crack crossing area according to the crack deflection path, calculating the actual propagation rate of the crack by combining the path proportion and stress gradient distribution of each stress gradient area after division, and correcting the life prediction output result, thereby improving the crack propagation path prediction precision and the fatigue life prediction evaluation precision.

The invention discloses an intelligent rock supporting method, and belongs to the technical field of rock supporting, and the intelligent rock supporting method comprises the steps that rock mass dynamic data are obtained through a rock mass stress sensor, a displacement sensor and environment monitoring equipment, and the rock mass dynamic data comprise rock mass stress, displacement, temperature and humidity; rock mass stress distribution is calculated based on rock mass dynamic data, and weak area coordinates and stress gradients are obtained; based on the weak area coordinates and the stress gradient, an optimal solution set of the anchor rod length, the pre-tightening force and the supporting plate thickness in the next construction is generated; and according to the optimization instruction, the work of the intelligent supporting device is dynamically adjusted, and the iterative optimization process is circulated until the construction is finished. Through the steps, the supporting scheme of the next supporting can be automatically adjusted according to the change of the rock mass stress after each supporting construction, so that the dynamic supporting scheme change of the stress state of the dynamically changed rock mass is realized.

The invention relates to the technical field of steel pile engineering simulation analysis, and discloses a steel pile oil cylinder stress and steel pile gravity center change model simulation analysis method, which comprises the following steps: acquiring oil cylinder pressure, steel pile displacement track data and geological parameters, and cleaning; extracting multi-dimensional features to generate dynamic load distribution parameters, and constructing a coupling relation model; the oil cylinder pressure and the steel pile displacement dynamic state are jointly verified, the space correspondence between the pressure gradient change and the gravity center shift is recognized, and the abnormal correlation is quantified; generating a system stability index, and judging whether to trigger control parameter correction; if correction is needed, a pressure compensation scheme is automatically generated. According to the method, through multi-dimensional data processing, coupling modeling and dynamic verification, precise analysis and intelligent control over oil cylinder stress and gravity center change in steel pile operation are achieved, the system stability and construction safety are improved, and the method is suitable for steel pile construction scenes such as ocean engineering.

The application discloses a method for pre-judging blast furnace material collapse based on static pressure, which comprises the following steps: collecting data of a static pressure measuring point by a computer; linearly fitting a real-time static pressure measuring point value and a static pressure measuring point elevation to obtain a function, a slope of the function is used as a pressure gradient reflecting a blast furnace gas flow and a material feeding feature to draw a pressure gradient change curve with time, and when a curve at a current time t satisfies condition A and condition B, it is determined that the blast furnace has a possibility of material collapse. The application adopts a linear regression method for the static pressure to obtain the pressure gradient, compared with directly analyzing the static pressure or a segmented pressure difference, the analysis of the pressure gradient greatly reduces the difficulty and workload of a technical personnel in analyzing the blast furnace gas flow, in addition, the condition A and the condition B for pre-judging the material collapse are combined by using the "and" mode, the long-period analysis and the instantaneous value analysis of the pressure gradient are taken into account, and the accuracy and the scientificity of the pre-judgment of the material collapse are ensured.

According to the copper alloy strip residual stress rapid evaluation and improvement method based on stress feedback, a warping measurement value is accurately mapped into a stress gradient parameter through a deformation and stress conversion model, and the aging bottleneck of a traditional method is broken through; according to the method, a double-track regulation and control mechanism driven by a delta sigma threshold value is constructed, medium and low stress regions are passivated and homogenized by means of cerium salt grain boundaries, a high stress region is subjected to targeted shape protection by means of a cerium salt and thiomalic acid composite film, dialectical unification of stress release priority and overall etching efficiency is achieved on the molecular level, and a scientific and efficient stress management and control mode is provided for copper alloy strip manufacturing.

The present application relates to the technical field of steel pile engineering simulation analysis, and discloses a simulation analysis method for force of a steel pile oil cylinder and a model of change of the center of gravity of the steel pile, comprising the following steps: obtaining oil cylinder pressure, steel pile displacement trajectory data and geological parameters and cleaning; extracting multi-dimensional features to generate dynamic load distribution parameters and constructing a coupling relationship model; jointly verifying the oil cylinder pressure and the dynamic displacement of the steel pile, identifying the spatial correspondence of pressure gradient change and center of gravity deviation, and quantifying abnormal correlation; generating a system stability index to determine whether to trigger control parameter correction; if correction is required, a pressure compensation scheme is automatically generated. Through multi-dimensional data processing, coupling modeling and dynamic verification, the method realizes accurate analysis and intelligent control of the force of the oil cylinder and the change of the center of gravity in steel pile operation, improves the system stability and construction safety, and is suitable for steel pile construction scenes such as ocean engineering.

This invention discloses an adaptive compensation control method for uneven settlement in soft strata, belonging to the field of settlement control in geotechnical engineering. The method involves collecting distributed micro-strain field and pore water pressure gradient data at the bottom of the foundation in the soft strata and inputting them into a stratum rheological evolution prediction model. Multi-scale spatiotemporal features are extracted using a spatiotemporal attention coding module to generate a stratum creep trend vector. The equivalent modulus correction coefficient is calculated using a virtual stiffness reconstruction algorithm to generate a dynamic stress wave excitation parameter set. Coherent stress beams are emitted using microarray actuators embedded in the bearing layer interface, and a dynamic stress-locking zone is constructed through constructive interference to form a virtual rigid support. The excitation parameters are corrected through a dual-loop adaptive feedback control mechanism combined with a heuristic optimization algorithm until the micro-strain field returns to uniformity. Simultaneously, energy dissipation monitoring and safety mechanisms are added to mitigate the risk of soil liquefaction. This invention achieves active suppression and adaptive compensation for uneven settlement in soft strata, improving the accuracy of settlement control.

The invention relates to an offshore wind power jacket pipe joint component design and manufacturing method, which comprises the following steps of: establishing a pipe joint parameterized geometric model by taking a deep sea shellfish shell growth mechanism as an initial topological structure; inputting the extreme environmental parameters of the sea area into a pre-constructed GAN model, performing fitting training by a generator in the GAN model, and outputting a gradient material space distribution scheme of jacket pipe nodes; performing optimization processing on the gradient material space distribution scheme based on a multi-target genetic algorithm to obtain an optimal solution of a target stress gradient and material distribution; by utilizing the growth mechanism of a deep-sea shellfish shell, the topological design of the pipe joint is realized, a large number of structural simulation analysis data and parameters are provided, the wall thickness of a steel plate of the pipe joint can be obviously reduced, the stress concentration phenomenon at the pipe joint is changed, the fatigue performance of the joint is improved, and meanwhile, the comprehensive manufacturing cost of the overall structure of the jacket is greatly reduced.

This invention discloses a method and system for characterizing the stress field transfer direction in coal seams, relating to the field of coal seam safety monitoring technology. The method includes: establishing a quantitative coupling relationship between stress and wave velocity in coal and rock samples through laboratory testing; inverting the three-dimensional wave velocity field of the working face based on microseismic monitoring data, and obtaining the corresponding three-dimensional stress field distribution according to the coupling relationship; calculating the transfer vector of the anomaly area by tracking the temporal changes of the centroid of the stress anomaly area, and obtaining the stress gradient change vector by calculating the temporal changes of the stress field spatial gradient; performing consistency analysis on the transfer vector and the stress gradient change vector, and determining the corresponding direction as the dominant transfer direction of the stress field in the coal seam region when the consistency meets preset conditions. This invention, through dual-path dynamic analysis and cross-validation, can characterize the transfer direction of the coal seam stress field at a regional scale, providing a new technical approach for the monitoring and early warning of coal and rock dynamic disasters.

The invention relates to a connection hole site iterative optimization method based on multi-dimensional stress characteristic driving. The problems existing in layout optimization of connecting hole sites of plate / shell components at present are solved. Firstly, the center position of a design domain inner hole is parameterized; calculating at least two of equivalent stress, stress gradient, principal stress direction and strain energy density under a predefined load; calculating a comprehensive influence function through a method of normalizing and weighting the multi-dimensional features; carrying out iterative optimization on the position of the guide hole in the first principal stress direction, calculating a multi-dimensional stress feature and a comprehensive influence function in each iteration, and carrying out dynamic updating on a feasible region by considering geometric and process constraints at the same time; after iterative calculation convergence, a calculation result is output, and key index verification is carried out; checking whether geometric constraints and process manufacturing conditions are met or not; and generating a sample piece and carrying out physical test verification. According to the method, optimization of multiple performance targets such as strength, rigidity and fatigue life can be achieved, and the method can also be closely combined with engineering practical application.

The invention discloses a wheel disc characteristic structure simulation part design method based on an additive manufacturing thought, which comprises the following steps of: firstly, establishing a parameterized model of a wheel disc, and acquiring stress field data of a wheel disc characteristic structure by adopting a finite element analysis means; secondly, based on stress field data of the wheel disc feature structure, an MATLAB program is written to solve a stress gradient space curve; and finally, determining the initial section size of the simulation piece based on the test condition of the testing machine, determining a size iterative formula based on the additive manufacturing idea, iteratively calculating the profile curve of the simulation piece according to the stress gradient space curve, and determining the configuration of the simulation piece in combination with the test condition of the testing machine. Compared with the prior art, the method has the advantages that stress gradient path selection, design of the initial configuration of the simulation part and size optimization of the initial configuration are not needed in the whole design process, standardization and standardization of design of the wheel disc feature structure simulation part are greatly improved, repetition of the design process is fundamentally avoided, the design period is shortened, and the design efficiency is improved.

This invention discloses an experimental apparatus and method for a similar model of a rock wall expansion. The apparatus includes a transparent experimental chamber, a layered gelatin system, a terrain simulation system, a dynamic injection system, a multimodal monitoring system, and a data acquisition and processing system. By independently adjusting the stiffness and density ratios of the upper and lower gelatin layers, combined with a detachable double-slope terrain mold, a systematic study of the coupled effects of multiple factors such as terrain, stiffness layering, density layering, and injection rate is achieved. The three-dimensional morphological evolution of the rock wall is simultaneously monitored using a multi-view high-speed camera, and the full-field displacement field, strain field, and principal stress direction during the rock wall expansion process are inverted in real time using digital image correlation technology. This reveals the control mechanism of stress gradient reversal caused by terrain on the lateral expansion and cessation of the rock wall. Furthermore, dimensionless analysis and boundary correction improve the similarity between the model and the natural prototype, providing a reliable experimental platform for volcanic eruption prediction and magma transport law research.

The invention discloses a method for establishing a two-dimensional CMC turbine blade surface Nusselt number engineering empirical relational expression, which comprises the following steps of: systematically researching the flow and heat transfer characteristics of different pressure gradient areas such as a suction surface front edge, a suction surface tail edge and a pressure surface middle section, extracting geometrical characteristic parameters of surface textures, and introducing a dimensionless correction factor, so as to establish a two-dimensional CMC turbine blade surface Nusselt number engineering empirical relational expression. A Nusselt number correction model suitable for different areas is constructed, and a heat exchange coefficient mapping relation from a smooth surface to a woven texture surface is realized. Compared with a traditional smooth surface or a general roughness empirical correlation formula, the model established by the method can more accurately reflect the influence rule of weaving texture features on the surface heat exchange distribution of different pneumatic areas, and the engineering applicability and calculation precision of heat exchange prediction are remarkably improved; and a reliable engineering analysis method and technical support are provided for heat transfer design, performance evaluation and structure optimization of CMC turbine blades and other high-temperature composite material parts.

The application discloses a kind of fatigue life simulation evaluation methods of new energy vehicle light weight aluminum alloy material, it is related to material life evaluation technical field;Microstructure image is collected and coupled feature is extracted by machine learning, complete heterogeneous data fusion and enhancement;Based on GAN generation topological optimization structure, in stress gradient dynamic grid, introduce VPSC model to describe anisotropy, construct dynamic finite element model;Fusion vehicle driving data, to LSTM prediction load, VMD decomposition and environmental correction, realize space-time correlation load spectrum reconstruction;Microscopically with phase-field model, macroscopically with XFEM crack tracking, bidirectional coupling transmission damage parameter, carry out multi-physical field coupling simulation;Bayesian inference is used to fuse simulation and test data, calculate life probability distribution, error is over limit when correcting parameter;The application ultimately reduces fatigue life prediction error, reduces the time consumption of single simulation, realizes life cycle assessment and visual early warning, provides efficient scheme for light weight design, promotes industrial technology upgrading.

This invention discloses a karst tunnel cave simulation experimental device for applying different gradient stresses. The device includes a first loading chamber, a second loading chamber, a third loading chamber, a top cover, a first oil pump, a second oil pump, a third oil pump, a first pressure regulating valve, a second pressure regulating valve, a third pressure regulating valve, a first strain gauge, a second strain gauge, a third strain gauge, and a high-speed camera mounted on the top cover. This karst tunnel cave simulation experimental device can apply different pressures to the lower, middle, and upper parts of a hollow rock specimen, thereby simulating the force exerted by different soil pressures at different burial depths on the cave. It can also observe and record the deformation and failure of the specimen using strain sensors and a high-speed camera. This device can conveniently simulate the structural changes of caves under stress gradients in engineering projects.

The utility model relates to the technical field of penetration testing, and provides multi-connected flexible wall penetration equipment which comprises a pressure control system, a gas-water conversion system and a plurality of flexible wall penetration testing systems. The pressure control system is provided with a first pressure passage and a second pressure passage, the first pressure passage outputs gas confining pressure, and the second pressure passage outputs gas osmotic pressure. And the gas-water conversion system is communicated with the second pressure passage and is used for converting the gas osmotic pressure into water osmotic pressure. The plurality of flexible wall penetration testing systems are communicated with the first pressure passage and the gas-water conversion system and are used for converting the gas confining pressure into water confining pressure and performing penetration testing on the plurality of samples under the consistent water confining pressure and water penetration pressure. According to the invention, synchronous and efficient penetration testing of a plurality of samples under the simulated actual stress condition is realized, and the device is especially suitable for low-permeability materials requiring accurate pressure gradient control and field stress condition simulation.

The application discloses a kind of wet process equipment PTFE tank stress temperature double parameter real-time monitoring system, the system includes following unit: data acquisition unit, for collecting PTFE tank stress and temperature data, obtains original stress-temperature time series data and carries out tank area stress distribution difference analysis, obtains stress distribution difference data;According to stress distribution difference data, the time-space correlation analysis of stress gradient and temperature gradient is carried out, and stress-temperature gradient coupling distribution data is obtained, and the application relates to the technical field of wet process equipment monitoring.This kind of wet process equipment PTFE tank stress temperature double parameter real-time monitoring system, reaches the real-time accurate collection PTFE tank stress temperature data, by multistage analysis optimization, constructs the monitoring model of adaptation different environment and is deployed to cloud platform.Can effectively evaluate coupling effect, realize abnormal early warning, guarantee tank safe operation, reduce fault risk and loss.

This invention discloses a gradient cryogenic forming method for deep-cavity thin-walled curved parts, relating to the field of metal sheet processing technology. The method includes: dividing the sheet material to be formed into a flange area, a suspended area, and a molding area; establishing a stress gradient model that prevents cracking and wrinkling based on the radial and circumferential stresses of each deformation area, and accordingly determining cryogenic cooling conditions and blank holder force loading conditions; placing the sheet material on a die and pressing the flange area; injecting a cryogenic medium into a normal-pressure buffer tank through a self-pressurizing tank, allowing the liquid portion to flow into the upper surface of the sheet material in the suspended area by gravity, thus constructing a gradient temperature field radially across the flange area, suspended area, and molding area; driving the punch downwards under a set blank holder force, causing the sheet material to deform in a coordinated manner within this gradient temperature field, ultimately forming a deep-cavity thin-walled curved part. This method effectively suppresses the simultaneous defects of cracking and wrinkling caused by concentrated deformation in the suspended area, achieving coordinated deformation in each area and ensuring a stable forming effect for the curved part.

The invention relates to the technical field of water treatment, and discloses an adsorption material for high-sulfur mining area groundwater pollution treatment and a preparation method thereof.The preparation method comprises the steps that a polymer matrix and functional filler are mixed to prepare a primary thin film, the primary thin film is fed into a cascade calendering unit, and edge transverse prestress is applied; the method comprises the following steps: generating a speed difference shear stress by adjusting a linear speed ratio between calendering rollers, inducing plastic deformation of a matrix and stripping at an interface so as to construct longitudinally communicated adsorption micro-channels, feeding back and adjusting the ratio of the rotating speed to the linear speed of a unit by utilizing the offset of a characteristic dominant frequency of an acoustic emission signal collected in real time relative to a reference frequency, compensating the discontinuity of a micro-channel structure, and finally obtaining the acoustic emission signal. The stress gradient in the width direction is eliminated through a stress field coupling mechanism, it is ensured that the topological structure of the material shows the full-width uniformity, active sites of the functional filler are forcibly exposed through a physical intervention means, the pollutant capturing capacity of the material is enhanced, and the technical problem of permeability degradation in the deep well environment is solved.

The invention relates to the technical field of metal casting, in particular to an intelligent casting method and system based on multi-dimensional parameter detection, and the method comprises the steps: monitoring the content of multi-point raw material elements in a molten pool in real time, and obtaining a component uniformity index by calculating the ratio of a content standard deviation to a self-adaptive updated standard deviation threshold value; whether putting compensation is carried out or not is decided by combining the raw material element deviation rate; the flow stability index is determined by monitoring the flow speeds of the sprue, the cross gate and the flow gate, and the pouring speed and pressure are cooperatively adjusted according to the flow stability index. The stress gradient is calculated based on multi-point surface stress values collected in real time, and the cooling water channel is dynamically adjusted to eliminate stress concentration. Closed-loop intelligent control over multiple key parameters in the whole casting process is achieved, the component uniformity and flow stability of the casting are effectively improved, cooling stress is restrained, and therefore the quality stability and the yield of the casting are remarkably improved.

The application discloses a rock unloading gradient damage test method based on non-uniform stress distribution and relates to the technical field of geotechnical engineering and rock mechanics test, and comprises the following steps: in a true triaxial servo loading device, a rock sample is divided into multiple layers along the thickness direction, and different loads are applied to each layer, so that a non-uniform stress gradient which continuously changes from the surface layer to the deep layer is formed in the rock sample. The application forms a non-uniform stress gradient which continuously changes from the surface layer to the deep layer and implements a step-by-step unloading from outside to inside, so that the whole test process is in a controllable spatial stress evolution environment, and the stress release and redistribution process under the surrounding rock excavation condition is truly simulated. Meanwhile, multi-source response information is synchronously obtained under the stable and continuous multi-layer stress state, and spatial reconstruction is carried out, so that the evolution characteristics of rock mass gradient damage are completely revealed, and a reliable test means for studying the rock mass damage mechanism under the non-uniform stress unloading condition is provided.

The application provides a touch screen production optimization method, comprising: according to initial distribution characteristics, adopting a preset convolutional neural network model to extract key characteristics of stress distribution and material hardness change, obtaining variation trend data of stress gradient and hardness difference in each region; if each adjustment value in the preliminary adjustment scheme of the cutting parameter exceeds the preset stress gradient threshold, then the genetic algorithm iterative calculation is called through the adaptive control framework to generate final cutting parameter configuration data; comparing the stress distribution dynamic change value and the substrate utilization rate change value in the actual cutting process, if the stress deviation exceeds the standard or the utilization rate is lower than the preset standard, then the feedback adjustment signal data is generated; according to the feedback adjustment signal data, the parameter weight value in the adaptive control framework is adjusted, and combined with the current environmental temperature fluctuation data and the material hardness change data, the stable cutting execution scheme data is generated. The application also provides a system for producing a touch screen by using the above method.

The invention belongs to the technical field of material and structure fatigue tests, and discloses a method for predicting the fatigue life of a casing notch characteristic element based on multiple engineering detectable cracks. The method comprises the following steps: designing a structural characteristic element containing notch characteristics based on the structural characteristics of a combustion chamber casing, and establishing an initial fatigue life prediction model of a material; in order to correct the influence of the average stress on the fatigue life of the structural characteristic element, verifying the feasibility of various average stress correction models based on a test result, analyzing a prediction error, and selecting the average stress correction model as a fatigue life prediction model of the material; on the basis of the established material constitutive model and finite element software, simulating a fatigue loading process of a structural feature element, and averaging node stress substitution numbers within a hypothetical double engineering detectable crack surface range to obtain average stress and eliminate the influence of stress gradient; and substituting the extracted algebraic average stress into the established fatigue life prediction model to realize fatigue life prediction of the combustion chamber structure characteristic element.

The utility model discloses a gradually-changed rod body, and relates to the technical field of anchoring tools. The gradient rod body comprises a main body sleeve and a connecting sleeve, a plurality of multi-section reinforcing bars are arranged in the main body sleeve and comprise upper reinforcing bars, middle reinforcing bars and lower reinforcing bars, the upper reinforcing bars, the middle reinforcing bars and the lower reinforcing bars are sequentially connected from top to bottom, and the upper reinforcing bars and the middle reinforcing bars are connected through the connecting sleeve. And the middle reinforcing steel bar is connected with the lower reinforcing steel bar through the connecting sleeve. The diameter of the upper reinforcing steel bar is larger than that of the middle reinforcing steel bar, and the diameter of the middle reinforcing steel bar is larger than that of the lower reinforcing steel bar. Reasonable reinforcement is carried out according to stress conditions of different portions of the rod body, the rod body with the maximum stress gradually changed is formed, the use amount of steel bars is reduced, the engineering cost is reduced, and meanwhile the structural strength and stability of the anchor rod are guaranteed.

The invention discloses a rectangular web-steel pipe composite space node structure with continuous rigidity distribution, which is suitable for the through connection of a main pipe and an inclined strut of an offshore wind power jacket. A rectangular web plate with a spatial curved surface is arranged on the outer wall of a main pipe of the node, and continuous curvature and continuous thickness distribution are formed through a web plate abduction function, a thickness gradual change function and a smooth transition surface, so that the outer surface of the node is kept continuous in the normal direction and the curvature direction. The web curved surface is defined in a parameterized mode, the abduction amount of the web curved surface changes smoothly in the width and height directions, the thickness is locally enhanced according to the direction of the inclined strut, bending moment, axial force and shearing force input by the inclined strut form planar diffusion on the web curved surface, and rapid turning of traditional node force flow in a narrow intersecting belt is avoided. The smooth transition curved surface between the main pipe and the web ensures that the whole structure has no geometric mutation. Hot spot stress and stress gradient are remarkably reduced, the fatigue life of the joint is prolonged, and the joint is suitable for offshore wind power jackets bearing cyclic loads and large steel structure joints.

The application discloses a new stress gradient characterization and verification method, belongs to the fatigue life prediction field of materials, and specifically comprises the following steps: firstly, a finite element model A of an actual mechanical structure is established, a dangerous point is selected, and an elastic stress gradient influence factor Y is calculated; then, notch finite element models with different stress concentration coefficients K t Values are established, and each dangerous point a' is arranged, stress gradient influence factors Y1, Y2,... Y n are calculated at the dangerous point a' in each model, compared with Y, and used for reflecting the stress gradient distribution at the dangerous point a; finally, Y is introduced into a life equation, fitting parameters are introduced simultaneously for correcting Y, a corrected life model is obtained, and the stress gradient at the dangerous point a is characterized; and a stretching test piece containing at least two notches is designed, different notch sizes are designed, and the stress gradient at the dangerous point a is verified; and the application improves the precision of predicting the fatigue life on the actual mechanical structure.

This invention discloses a wide-range gradient controllable residual stress calibration block and its preparation method, belonging to the field of stress calibration technology. The preparation method includes processing a carburized steel substrate into a blank and sequentially performing carburizing and quenching, shot blasting, grinding to remove the surface oxide layer, and shot peening. The shot-peened blocks are divided into at least two groups, and tempered in different temperature ranges to obtain blocks with different residual compressive stress levels. The different temperature ranges are selected from at least two of the following: 50-150℃, 150-250℃, and 350-450℃. At least a portion of the tempered blocks undergoes surface corrosion treatment to remove the deformation layer of a predetermined depth and fine-tune the residual stress value. Finally, the blocks are rust-proofed and stored. This invention solves the problems of existing calibration blocks having single stress values, poor stability, and short shelf life. It achieves the acquisition of stable calibration blocks with different stress gradients within the same material batch.