303 results about "Equivalent stress" patented technology

The invention provides a vibration fatigue life predication method and system for a micro-packaging assembly. The method comprises the following steps: creating a vibration simulating finite element model according to the structures of the micro-packaging assembly and a fixing part; extracting the verification characteristics parameters; modifying the vibration simulating finite element model according to the verification characteristics parameters and the experimental characteristics parameters of the micro-packaging assembly to obtain a vibration simulating model; performing random vibration stress response simulation analysis for the micro-packaging assembly according to the vibration simulation model to obtain a dangerous vibration fatigue point; extracting equivalent stress power spectrum density of the dangerous vibration fatigue point under the random vibration load; converting the equivalent stress power spectrum density to obtain cyclic stress time domain data; calculating the vibration fatigue life of the dangerous vibration fatigue point under the random vibration load according to an S-N curve and the cyclic stress time domain data of the dangerous vibration fatigue point; predicating the vibration fatigue life of the micro-packaging assembly by the method of synchronously extracting the response data of the fixing part and the micro-packaging assembly. With the adoption of the method and system, the testing accuracy is improved.

The invention discloses a service life based high-temperature container creep fatigue strength design method. The method comprises the steps of 1, performing structure preliminary design; 2 determining load and temperature conditions and the design service life requirement; 3, determining dangerous sections; 4, calculating the equivalent stress and strain range; 5, calculating reference stress; 6, determining whether plastic collapse occurs; 7 determining whether the plastic ratchet occur; 8, determining whether creep damage is important; 9, estimating fatigue damage of each cycle when the creep damage is not important; 10, determining whether the fatigue damage is important; 11, estimating the creep damage when the fatigue damage is not important; 12, estimating damage of each cycle when the creep damage and the fatigue damage are non-ignorable; 13, estimating creep-fatigue total damage; 14, performing result analysis and structural design improvement; 15, completing structural design. According to the method, the foundation is laid for national establishing of creep and fatigue failure mode based high-temperature pressure container design standards and achieving design and manufacture of high-temperature pressure containers according to the service life.

It relates to a turbine rotor low cycle fatigue durability loss on line monitoring system, featuring in its computation, application server and software, database server, outside system interface, turbine control system DEH and parameter testing point, web server and user browser that connects with the computation and application server and each end item user browser respectively, with the computation and application server connecting with the data base server which connects with the turbine control system DEH and parameter testing point through the outside system interface. It is made of two processes, with the no.1 using artificial nerve network to determine turbine rotor equivalent stress coefficient, the no.2 process being on line computation, monitoring and control of the turbine rotor cycle fatigue loss. It realizes the working times of the turbine rotor of 10000 times.

The invention discloses a rolling mill transmission system key component fatigue life early warning method based on load spectrum analysis. The method is characterized by comprising the following steps: 1, obtaining a rolling mill transmission system key component load spectrum through real-time monitoring in a rolling mill working process; 2, based on a computer simulation technology, obtaining a stress distribution and conversion coefficient of a rolling mill transmission system key component; 3, obtaining a corresponding stress spectrum by performing conversion processing on the load spectrum measured in the first step; 4, compiling an equivalent stress amplitude histogram by performing statistics on the stress spectrum after processing in the third step by use of a cyclic rain flow counting method; and 5, calculating fatigue life circulation frequency of a transmission part by use of a correction Miner method, and converting the fatigue life circulation frequency into a fatigue life taking a year as a unit. The method solves the problems of large calculation amount and high calculation complexity in a conventional fatigue life calculation method, has quite high applicability and operability and is high in engineering practicality.

The invention discloses a prediction method for a microstructure evolution law of 20CrMnTiH steel in a thermal deformation process. According to the method, a Deform-3D based secondary development microstructure simulation module is combined with the thermal deformation process; a mathematic model of a microstructure evolution mechanism of the 20CrMnTiH steel is obtained by a physical experiment; dynamic recrystallization, static recrystallization, meta dynamic recrystallization and austenite grain growth microstructure analysis and simulation modules for a material are compiled by adopting an Absoft Pro Fortran language; and microstructure distribution of a thermal deformation workpiece in different process conditions is calculated by calling the microstructure modules, and macroscopic field quantity such as a temperature field, an equivalent stress-strain field and a microstructure mutual influence law in the thermal deformation process is analyzed to realize prediction of the microstructure distribution and evolution law of the 20CrMnTiH steel in the thermal deformation process, thereby providing technical bases for setting and optimizing thermoforming process parameters of 20CrMnTiH steel products in actual production, and providing theoretic bases for obtaining high mechanical performance of the material by controlling deformation conditions in a thermal precision forming process.

The invention discloses an external pressure self-intensification cylinder and a design calculation and a manufacturing method thereof, which is used for improving the safety and the bearing capability of a pressure vessel and solving the phenomenon of lacking external pressure self-intensification vessel design calculation and manufacturing methods and the technical problems of unsafety and the like caused by complex or inaccurate design calculation of the existing internal pressure self-intensification technology. The invention has the following technical scheme key points: adopting a special bearing capability, plastic zone depth and cylinder wall thickness calculating formula to ensure that the equivalent stress of the total stress (the sum of stress caused by operation pressure and self-intensification residual stress) in the wall of the cylinder is not more than the yield strength sigma y of cylinder material; or ensuring that the equivalent stress of the residual stress in the whole cylinder wall of the self-intensification cylinder and the equivalent stress of the total stress are both not more than sigma y. The invention also provides a maximum diameter ratio which does not yield after the self-intensification pressure is removed no mater how deep the plastic zone is when the self-intensification technology is applied. The technical scheme of the invention is also suitable for an internal pressure self-intensification cylinder.

The invention discloses a prediction method of a crack propagation life of an aircraft body. The prediction method comprises the following steps: obtaining a random loading spectrum of an aircraft in flight according to the practical flight situation of the aircraft; dividing the obtained random loading spectrum into a plurality of sections, and respectively performing rain-flow counting and constant amplitude on each section, so that each section is approximated as a block loading spectrum; according to an Miners progressive damage theory, calculating a cycle life lambda effected on a crack of each block loading spectrum under the state of a corresponding stress ratio R, performing a fatigue test under the suitable stress ratio, and obtaining a corresponding stress-life curve; according to an equal defect theory, selecting the correspondence life curve under the suitable stress ratio R in the stress-life curve, and obtaining the equivalent stress Seq corresponding to the same life by a point tracing method; then, according to the R and the Seq, obtaining a maximum stress value sigma max and a minimum stress value sigma min of the equivalent cyclic stress; according to parameters of the equivalent cyclic stress, calculating the propagation rate of the crack when the obtained block loading spectrum is acted on the aircraft body.

The invention discloses a method for analyzing static strength characteristics of a turbomachinery blade based on CPU+GPU heterogeneous parallel computing. The method comprises the following steps of firstly, establishing a finite element model, computing the total stiffness matrix of the model, then, computing the centrifugal load vector and the pneumatic load vector of the turbomachinery blade, performing displacement constraint and coupling of a node, and correcting the total stiffness matrix; and then, solving an equation set formed by the total stiffness matrix and the load vector in parallel by using CPU+GPU, obtaining a node displacement vector, then, computing the principal strain and the VonMises equivalent stress, drawing a distribution cloud picture, and finally, performing safety check. By means of the method disclosed by the invention, for static strength analysis and design of the turbomachinery blade, project planners can perform operation conveniently; simultaneously, due to an adopted CPU+GPU parallel algorithm, the computing speed of a finite element method can be effectively increased; an accurate and rapid blade static strength characteristic analysis result is provided for design of the turbomachinery blade; and the design period of the turbomachinery blade is greatly shortened.

The invention discloses a method for simplifying an analysis model of a fatigue loading effect of an orthotropic steel bridge deck. The method comprises steps as follows: 10), performing finite element modeling on a large-span cable bearing bridge structure system, and building an overall structure dimension model; 20), building a partial detailed steel box girder model of the overall structure dimension model with a submodel method, and calculating an equivalent stress amplitude exact solution of a steel bridge deck part of the partial detailed steel box girder model; and 30), simplifying the partial detailed steel box girder model into a partial steel bridge deck stressing structure system, performing optimization analysis on a parameter value of the structure system based on the equivalent stress amplitude exact solution obtained in the step 20), and determining a simplified model for analyzing the fatigue loading effect of the steel bridge deck. The simplified model can guarantee the accuracy of a calculation result and improve the calculation efficiency for analyzing the fatigue loading effect of the orthotropic steel bridge deck greatly at the same time.

The invention discloses a wall thickness linear model-based pipe mechanical property hydro-bugling testing method, to solve the problems that the conventional pipe mechanical property hydro-bugling testing method is difficult to measure pipe wall thickness and discontinuous in experiment. The method comprises the following steps of: firstly, testing the initial wall thickness, the outer radius and the bulging area length of the pipe to be tested; secondly, putting the pipe to be tested between an upper die and a lower die, and sealing two ends of the pipe to be tested; thirdly, filling a high-pressure liquid medium into the pipe to be tested; fourthly, recording the pressure and the bulging height of the high-pressure liquid medium in the bulging process of the pipe to be tested in real time till the pipe to be tested is cracked; fifthly, measuring the wall thickness of a crack point of the pipe to be tested, and calculating and obtaining the wall thickness of each moment in the bulging process according to the wall thickness linear model; and sixthly, calculating and obtaining an equivalent stress stain curve of the pipe. The method is applied to pipe mechanical property hydro-bugling testing.

The invention relates to an evaluation method for reliable life of blade vibration fatigue of a gas compressor impeller of an automotive turbosupercharger. The method comprises the following steps: firstly, the operation condition of the automotive turbosupercharger and the working state parameters of the gas compressor impeller are determined; then, the dangerous parts of the blade vibration fatigue of the gas compressor impeller and the stress parameters of every corresponding working condition are determined; then, the fatigue strength of the dangerous parts of the blade vibration fatigue of the gas compressor impeller is determined by adopting a test method to compare the magnitude relation between the equivalent stress of the dangerous parts of the blade vibration fatigue of the gas compressor impeller and the fatigue limit of the blades under different working conditions and determine the effective stress parameters for evaluating the blade vibration fatigue life of the gas compressor impeller; the probability distribution characteristics of the blade vibration fatigue life of the gas compressor impeller and the reliable life meeting different reliability requirements are determined. The method can evaluate the reliable life of the blade vibration fatigue of the gas compressor impeller in the development stage of the turbosupercharger, and can preferably guide the structural design and reasonable use of the gas compressor impeller.

The invention discloses a nonstandard wind field oriented wind turbine generator fatigue life efficient assessment method. The steps comprises: 1) according to equivalent fatigue load of a to-be-assessed wind turbine generator under different wind resources, establishing a fatigue load assessment database; 2) detecting actual wind resource value of the to-be-assessed wind turbine generator on a target machine position in a nonstandard wind field, to obtain the equivalent fatigue load corresponding to the actual wind resource value; 3) comparing the equivalent fatigue load with the standard design load of the wind turbine generator, determining whether the fatigue life in the target machine position is in the design range or not; 4) converting the equivalent fatigue load to a corresponding equivalent stress value and calculating a fatigue damage value of the target machine position, and determining whether the fatigue damage value obtained by calculation is in the preset range. The method can effectively assess the fatigue life of the wind turbine generator in the nonstandard special wind field, and is advantaged by simple implementation method, low cost, and rapid and efficient.

The invention provides a cross-shaped test piece biaxial tensile test based yield criterion evaluation method. According to the relation of the real stress in a rolling direction and plastic strain, the relation of biaxial directional stress and equivalent stress can be deduced by adopting a yield criterion, the relation of plastic strain in a biaxial direction and equivalent plastic strain can bededuced, the relation of biaxial directional strain and the equivalent plastic strain can be obtained, and therefore, the relation of stress and strain in the biaxial direction can be obtained; dataof the equivalent stress and the equivalent plastic strain can be measured by a test, so that data of elastic and plastic stages in the biaxial direction can be obtained; the expressions of two curvescan be obtained through curve fitting, contrast can be performed on the biaxial directional data measured by the test and the expressions, and the prediction precision of the deformational behavior of a material corresponding to the yield criterion can be evaluated. The contrast of the difference between the relation of stress and strain in the biaxial direction obtained by the test and the yieldcriterion in the whole plastic stage can be realized; and the limitation that traditional methods can only compare the difference between a test yield point and the yield criterion under a certain equivalent plastic strain can be overcome.

The invention relates to a life-based design method for the fatigue strength of an ultrahigh-pressure container. The design method comprises the following steps: firstly carrying out primary structure designing; then carrying out an optimal design of self-enhanced treatment according to the principle of minimum shearing stress; then calculating by utilizing finite element software so as to obtain largest local equivalent stress, and comparing with the designed fatigue strength, if the designed fatigue strength is met, calculating the minimum initial fatigue crack length according to a design pressure and a threshold value of fatigue crack propagation of materials; determining the maximum fatigue crack length by utilizing the fracture toughness of the materials and establishing an accurate description equation on the basis of data of a fatigue crack propagation test; and carrying out iterative calculation on the basis, judging whether the fatigue design life is met, if so, finishing the structure design. The design method has the advantages that multiple risk factors in the process of manufacture and operation of the ultrahigh-pressure container are considered and controlled at a design phase, and the fatigue design life is given according to a modern numerical calculation technology; the designing method is safer compared with a conventional elastic-plastic design method and is more accurate and reasonable compared with the existing fracture-mechanics design method.

The present invention discloses a multiaxial creep-fatigue prediction method based on ABAQUS, which comprises: S1: establishing an ABAQUS finite element model, and defining the viscoplastic constitutive equation of the material to be tested by means of the user subroutine UMAT; S2: determining the model parameters required by the viscoplastic constitutive equation; S3: establishing the fatigue damage calculation model and creep damage calculation model of the multiaxial stress-strain state of the material to be tested; S4: establishing an ABAQUS finite element model under the multiaxial stress-strain state, and calculating the stress-strain tensor of each cycle based on the defined viscoplastic constitutive equation and the model parameters; S5: calculating the equivalent stress and equivalent plastic strain by means of the user subroutine USDFLD, and superimposing the fatigue damage and creep damage of each cycle according to the linear cumulative damage criterion to obtain the crack initiation life of the material to be tested based on the fatigue damage calculation model and creep damage calculation model in combination with the stress-strain tensor.

The invention discloses a generating method of a finite element mesh in a thin-wall curved surface structure, aiming to solve the technical problem of great equivalent stress of a traditional design method of a finite element model in a perforated thin-wall conical curved surface structure. The technical scheme comprises the following steps of: firstly, generating a plane finite element mesh on a parameter plane by adopting a solid modeling method; then, generating network nodes in a space thin-wall curved surface structure through a parametric mapping relation by adopting a direct generating method; and generating a finite element mesh in the space thin-wall curved surface structure by utilizing corresponding unit topology information on the parameter plane. Compared with the prior art, the maximum equivalent stress of the finite element model in the perforated thin-wall conical curved surface structure in the same size is greatly reduced.

The invention relates to an online calculation-control method on the equivalent stress of the high-middle-pressure rotor of turbine, wherein if said factor is over preset value, it can online control the temperature change rate of main steam, and the load change rate to improve equivalent stress and prolong the service life. If the factor reaches the alarm value, it will alarm, and stop in preset time to control the equivalent stress and prolong the service life.

The invention discloses a triaxial stress strength designing method for a vertical well casing string. The triaxial stress strength designing method for the vertical well casing string comprises the following steps of: determining the steel grade, the wall thickness and the setting lengths of a first-section casing; performing internal pressure strength check and tensile strength check on the top of the first-section casing; calculating the setting lengths Lon and Lan of the first-section casing; and performing internal strength and extrusion strength check on the first-section casing till the designed well depth is met. By simultaneously considering the influence of coactions of an axial force, an external extrusion force and an internal pressure on the strength of the casing, the magnitude of the triaxial stress is calculated, an equivalent stress is calculated and supposed to be equal to the yield strength of the casing, and the strength of the casing is designed, so that the design is more reasonable and the designed vertical well casing string is more durable.

The invention discloses a centrifugal gas compressor impeller disc section shape optimization method. A parametric modeling mode is adopted in the centrifugal impeller disc section shape, the impeller disc section shape is described with fewest design parameters, and the impeller disc section shape is optimized by combining a neural network approximate model and an optimization design method, so that the equivalent stress of the impeller is effectively reduced by over 7.4 percent under the condition of ensuring that the weight of the impeller is not increased, and the work reliability of the impeller is improved. By the design method, the strength design period of the impeller is greatly shortened, the design result is reliable, and the design cost is saved; and the method has high socialbenefit and popularization value.

The invention discloses a high-low cycle composite fatigue life prediction method of an aero-engine turbine blade, which comprises the following steps of correcting composite fatigue damage into highcycle fatigue damage, low cycle fatigue damage and coupling damage based on a linear cumulative damage model; defining high-cycle damage and coupling damage as variable damage based on service load characteristics of the aero-engine; determining variable damage as a function of high-cycle fatigue life and four characteristic parameters according to the high-cycle and low-cycle composite test loadspectrum, obtaining an expression of the variable damage, introducing an equivalent force amplitude ratio, establishing a high-cycle and low-cycle composite fatigue life prediction model, and predicting the composite fatigue life of the high-cycle and low-cycle composite fatigue life prediction model. According to the method, the fatigue life of the turbine blade under the composite loading condition can be rapidly measured by the aero-engine, and the theoretical reference is provided for reliability design and evaluation of metal materials and the turbine blade.

The invention belongs to the relevant technical field of the fatigue life calculation of a metal structure, and discloses a fatigue life assessment method based on an engineering machinery structure.The method comprises the following steps that: carrying out finite element analysis on the engineering machinery structure, and combining with a practical operating situation to determine a fatigue dangerous area; carrying out a dynamic stress testing experiment to obtain the stress time history of the fatigue dangerous area in multiple practical operating circulations; carrying out rain-flow counting, average stress correction and equivalent damage conversion on the stress time history in each operating circulation in sequence to obtain equivalent stress and equivalent circulation frequency corresponding to each operating circulation; and for the equivalent stress and the equivalent circulation frequency obtained each time, through a nonlinear cumulative damage theory, calculating the cumulative damage and the fatigue life of a bucket rod structure. By use of the method, the rain-flow counting method and the nonlinear cumulative damage theory are organically combined, the influence ofa loading sequence between the operating circulations is considered, a calculation process is simplified, calculation accuracy is improved, and the method is suitable for engineering application.

The invention discloses a uniaxial fatigue S-N curve-based hard metal material multi-axis high-cycle fatigue failure prediction method. According to the method, with a uniaxial tension fatigue and pure torsion fatigue S-N curve adopted as a boundary condition, and the equivalent stress amplitude and equivalent stress amplitude ratio of a material in the multi-axis fatigue loading process of the material are calculated; with the equivalent stress amplitude and equivalent stress amplitude ratio adopted as damage parameters, a fatigue S-N curve obtained from uniaxial fatigue is calculated; and a hard metal material multi-axis high-cycle fatigue failure life prediction model containing stress amplitude ratio and average stress influence is established. The method is suitable for a situation where average stress does not exist. Existing multi-axis fatigue life prediction models perform multi-axis fatigue tests under corresponding loading modes, and as a result, test cost is relatively high. Compared with the existing models in the prior art, the method disclosed by the invention is simple in form, and can obtain a uniaxial fatigue S-N curve just through a single-axis fatigue test or manual check, so as to accurately predict the fatigue life of a hard metal material under multi-axis high-cycle fatigue loading in the presence of a stress amplitude ratio and average stress.