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100 results about "Intensity factor" patented technology

Intensity factor. A multiplying factor used in planning activities to evaluate the foreseeable intensity or the specific nature of an operation in a given area for a given period of time.

Method for estimating remaining fatigue life of main metal structure of crane

The invention relates to a method for estimating the remaining fatigue life of a main metal structure of a crane. The method is applied to the compiling of actually measured load spectrums, the measurement of material fatigue crack propagation curves, the nondestructive detection of hazardous locations and the estimation of the remaining fatigue life of the main metal structures of the large cranes at relatively higher working levels in shipyards, ports and the like, and is also applied to the estimation of the remaining fatigue life of the cranes of other types. The method comprises the following steps of: (1) acquisition of the load spectrum; (2) measurement of material performance; (3) detection of an initial crack location and an initial crack size; (4) acquisition of a crack stress intensity factor; and (5) estimation of the remaining fatigue life. In the method, factors such as the existence of a crack in the structure, the detection of the location and size of the actually crack, and the like are taken into account, and the nondestructive detection is performed on the hazardous location; therefore, the remaining fatigue life of the metal structure of the crane can be accurately estimated.
Owner:GUANGZHOU ACAD OF SPECIAL EQUIP INSPECTION& TESTING

Photovoltaic model establishment method applicable to dynamic overall-process simulation of power system

The invention relates to a photovoltaic model establishment method applicable to the dynamic overall-process simulation of a power system. A photovoltaic generation module is modeled, a temperature factor and an illumination intensity factor in the medium and long-term process have the characteristics of fluctuation and indeterminacy, and an implementation method of a photovoltaic maximum power tracing model for the dynamic overall-process simulation of the power system is provided in consideration of the influence on photovoltaic generation caused by the change of the two factors. The photovoltaic maximum power tracing model adjusts the working voltage of a photovoltaic cell panel according to the volt-ampere characteristics of a photovoltaic power supply by using a maximum power point tracing control method, so that the photovoltaic cell panel can work in a maximum power output state, solar energy is utilized to the greatest extent, and the efficiency and performance of the photovoltaic generation are effectively improved. An inverter effectively controls the injection current of axes d and q by virtue of an inner ring current control loop and an outer ring current control loop, so that active power and reactive power can be controlled. The whole model meets requirements for electromechanical transient overall-process simulation and medium and long-term dynamic overall-process simulation of the power system.
Owner:STATE GRID CORP OF CHINA +2

Fatigue life prediction method for friction stir welded component based on small crack propagation

The invention discloses a fatigue life prediction method for a friction stir welded component based on small crack propagation, and belongs to the technical field of fatigue diagnosis and analysis ofmechanical structures. The method comprises the steps that a bone-shaped flat plate sample is prepared, fatigue small crack propagation replica tests under different stress loads and different stressratios are conducted on different areas of a joint, and a secant method is adopted for calculating the propagation rate of small cracks; a New-Raju model is adopted for calculating the stress intensity factor range of the small cracks of the joint; c values in the depth direction and a/2 values in the vertical direction of semi-arc shapes of fatigue crack propagation zones in fracture shapes of different areas of the joint, and the depth-to-length ratio 2c/a of the cracks is calculated; a curve of the propagation rate of the cracks along with the change of the stress intensity factor range isdrawn; an effective stress intensity factor is calculated; a formula of the propagation rate of the small cracks is determined; an initial crack size a0 and a critical crack size ac are determined; the formula of the propagation rate of the small cracks is integrated to obtain the fatigue life of the welded component. By means of the scheme, the fatigue life of the friction stir welded component can be more easily and accurately predicted.
Owner:BEIJING UNIV OF TECH

Testing method for mode I crack dynamic fracture overall process parameters under blast loading

The invention, a testing method for mode I crack dynamic fracture overall process parameters under blast loading, discloses the testing method for the dynamic crack initiation toughness, dynamic expansion toughness and dynamic crack arrest toughness of mode I crack under blast loading, and belongs to the technical field of geotechnical engineering. The configuration of an internal single crack disc specimen with a large size is an autonomous design; testing results cannot be influenced by reflected extension waves and transmission waves; and the method is suitable for researching the crack growth rate and growth behavior of the whole process. Blast loading adopts an 8# detonator; numeral calculation adopts a finite element difference software AUTODYN; and a result basically accords with atest. A load stress time history curve can be input into a finite element program ABAQUS; the time history curve of a dynamic stress intensity factor can be obtained; and the dynamic fracture toughness of a material can be determined through the fracture time of a crack. The specimen is simple in configuration and easy in processing; the test is concise and clear in process and convenient in operation; and researches on crack dynamic growth behavior and tests on the dynamic fracture toughness can be realized.
Owner:SICHUAN UNIV

Weld joint fatigue life prediction method

The invention provides a weld joint fatigue life prediction method, which comprises the following steps of obtaining node force and moment of a weld joint unit node through analysis by finite element software; then, according to the identical power application principle, obtaining the corresponding linear force and moment through the calculation by the node force and the moment of the weld joint unit node; obtaining the normal structure stress and the shearing structure stress in the thickness direction of the weld joint through conversion calculation; performing correction according to the actual expansion angle of cracks in the thickness direction; obtaining a corresponding equivalent stress intensity factor through the calculation on the corrected normal structure stress and shearing structure stress, and thus obtaining an average equivalent stress intensity factor on the practical crack expansion path; and using the average equivalent stress intensity factor as an evaluation parameter of the weld joint fatigue service. The weld joint fatigue life prediction method has the beneficial effects that the solution of a large-scale matrix equation is not needed, so that the calculation efficiency is greatly improved; and the method has the advantages of high calculation efficiency and high prediction precision.
Owner:HUNAN UNIV

Method for predicting upper and lower bounds of bounded uncertain plane crack stress intensity factors based on fractal theory

The invention discloses a method for predicting upper and lower bounds of bounded uncertain plane crack stress intensity factors based on a fractal theory. According to a geometric model including a crack structure, the geometric model is divided into a conventional region and a fractal region of crack tips by using an artificial boundary to establish a bounded uncertain structural static force response solution model in the conventional region; a William's general solution is used as an interpolation function to establish a bounded uncertain structural static force response solution model in the fractal region; then, assembly is performed to obtain a whole bounded uncertain structural static force response solution model including a crack structure, the upper and lower bounds of bounded uncertain generalized coordinates are calculated by adopting a first-order Taylor expansion based interval analysis method, and further the upper and lower bounds of the bounded uncertain plane crack stress intensity factors are calculated. The upper and lower bounds of the bounded uncertain plane crack stress intensity factors are calculated are accurately and efficiently obtained by adopting the method, and objective and effective data is provided for reliability evaluation and design of structures.
Owner:BEIHANG UNIV

Testing method for dynamic crack arrest toughness of I-type crack under middle-low speed impact load

InactiveCN108507887AArrest toughness can be calculatedSuitable for studying crack arrest phenomenaDesign optimisation/simulationMaterial strength using single impulsive forceLow speedTest procedures
The invention discloses a testing method for dynamic crack arrest toughness of an I-type crack under a middle-low speed impact load, and belongs to the technical field of rock and concrete engineering. A test piece is a V-shaped side open single crack half-bordered test piece designed by an inventor. The test piece has a V-shaped bottom boundary, and generates an oblique-upward compression wave under an impact load, and the horizontal component of the compression wave has a compression effect on an expansion crack, thereby further preventing cracking of the expansion crack. The testing methodadopts a middle-low speed drop hammer impact test device, finite element difference software AUTODYN is used for simulation calculation, and results are basically consistent with test results. An obtained load stress time history curve is inputted into finite element program ABAQUS, and a time-history curve of a dynamic stress intensity factor of the I-type crack is obtained. Finally, the dynamiccrack arrest toughness of a material is determined by the crack arrest time of the crack. The testing method for the dynamic crack arrest toughness of the pure I-type crack under the middle-low speedimpact load has the advantages of simple test piece configuration, easy processing, simple and clear test procedure and convenient operation, and is suitable for the research of crack dynamic expansion behaviors and dynamic fracture toughness tests.
Owner:SICHUAN UNIV

Wave type dynamic data reconstruction method based on singular boundary method

InactiveCN106168942ASimple mathMath is simple and efficientComplex mathematical operationsWave equationSea waves
The invention discloses a wave type dynamic data reconstruction method based on a singular boundary method. A wave equation time elementary solution is directly used as a kernel function, a source point intensity factor is used for replacing a source point singular item, no numerical value integrals, no singular integrals and no mesh generation are related, the wave equation time elementary solution is directly used as the kernel function, no complex mathematical manipulation exists, and the simple and efficient characters meet the feature requirements of wave type dynamic data reconstruction for quickness, stability and precision of the data reconstruction technology. Experiment comparisons show that when the technology is used for processing the wave type dynamic data reconstruction problem, under the condition of obtaining the similar precision, generally, only about 10% of time taken by a traditional linear boundary element algorithm is consumed, and the method has the advantages that the precision is high, calculation is quick, mathematics is simple, and the procedure is simple and convenient to conduct and can be applied to the engineering technical fields such as sound wave noise reduction, sea wave energy dissipation, earthquake prediction and other wave type data reconstruction and image processing.
Owner:HOHAI UNIV

Stress corrosion test method and device for metal sheet pre-cracked sample

The invention discloses a stress corrosion test method and a stress corrosion test device for a metal sheet pre-cracked sample. The method comprises the following steps of: fixing one end of the sample on a bearing wall, clamping the other end of the sample by using an upper clamping plate and a lower clamping plate and fixing; clamping a test section of the sample by using a corrosion environment test box; pre-estimating the initially applied stress field intensity factor according to the threshold stress field intensity factor of crack propagation of similar metal materials, wherein the pre-estimated value is greater than the threshold stress field intensity factor of the crack propagation of the metal materials; loading stress to the metal sheet sample, measuring the crack length of the sheet sample to obtain a crack stress field intensity factor, and stopping loading the stress when the crack stress field intensity factor is equal to the pre-estimated value; filling a corrosion medium in the corrosion environment test box; measuring the length of a crack at the tip of the pre-cracked sample at intervals of certain time; and measuring the crack length and the loaded stress after the crack stress field intensity factor is stabilized to obtain the threshold stress field intensity factor of stress corrosion crack propagation. The method is convenient to operate and high in measuring accuracy.
Owner:NANJING UNIV OF AERONAUTICS & ASTRONAUTICS

Analytic method of irregular building seismic response considering SSI (soil-structure interaction) general plane

The invention discloses an analytic method of irregular building seismic response considering an SSI (soil-structure interaction) general plane, comprising the operating steps of: firstly, representing mass eccentricity of each layer of a structure by using a polar coordinate and constructing a mass eccentricity structure dynamic equation under a bi-directional seismic action; secondly, representing SSI with five-DOF (degree of freedom) impedance function; thirdly, selecting a structural model, determining model parameters of soil and structure and constructing a general dynamic equation considering SSI general mass eccentricity structure; and fourthly, performing translation-torsion coupling response analysis to the general mass eccentricity structure in a frequency domain based on unitization of an intensity factor of an earthquake spectra. According to the method, influences of coaxial mass eccentricity and non-coaxial mass eccentricity to translation-torsion response of the structure in the case of general mass eccentricity are respectively analyzed, and an arithmetic mean square root of plane central displacement and acceleration of each layer of the structure is calculated and obtained. The method is characterized in that the polar coordinate is employed to represent the non-coaxial eccentricity of the structure. The method has the advantages that the eccentric position of the structure can be flexibly set; and the influence of the non-coaxial eccentricity to the seismic response of the structure is given.
Owner:SHANGHAI UNIV

Method for calculating three-dimensional crack propagation fatigue life of spherical shell surface

The invention belongs to a deep sea engineering technology and particularly relates to a spherical shell surface three-dimensional crack propagation fatigue life calculation method. The method comprises the following steps of establishing a complete spherical pressure-resistant shell initial geometric model; endowing the spherical shell model with material parameters and section attributes, dividing grids, and setting boundary and load conditions; establishing an initial crack model; endowing material parameters to the crack model, defining section attributes, dividing grids and determining the positions of the grids; importing the two models to generate a complete spherical shell finite element numerical model locally containing surface crack defects; solving an initial crack leading edgestress intensity factor value by adopting an M integral method; reading and running a fatigue life calculation model program; setting automatic crack propagation parameters; and obtaining a sphericalshell surface three-dimensional crack propagation fatigue life numerical value based on a self-defined propagation program. According to the method, finite element analysis software and fracture mechanics analysis software are combined to calculate the three-dimensional crack propagation fatigue life of the surface of the spherical shell, and applicability of the method is verified through numerical simulation.
Owner:JIANGSU UNIV OF SCI & TECH

Explosion loading electric measurement-dynamic photoelasticity hybrid experiment system and method

The invention discloses an explosion loading electric measurement-dynamic photoelasticity hybrid experiment system and method. The system comprises a laser light source (1), a beam expanding mirror (2), a convex lens A (3), a polaroid A (4), a quarter-wave plate A (5), a quarter-wave plate B (6), a polaroid B (7), a convex lens B (8), a high-speed camera (9), a computer (10), an experiment loadingplatform(11), a delay and controller (12), a multi-channel pulse igniter (13), a super-dynamic strain gauge (14), a data acquisition instrument (15), a test piece (33), explosive cartridges(34), a bridge box, a signal line, a shield line and a strain gauge. The system combines the advantages of two experiment methods, can measure various mechanical parameters, such as moving crack spreading speed, crack tip region strain, dynamic stress intensity factor and dynamic fracture toughness, and can also obtain information of test piece total stress field dynamic photoelastic fringes and focal speckle series images and the like; and by comprehensively comparing and analyzing the data obtained by the two methods simultaneously, a propagation mechanism of explosion-induced moving cracks and interaction of the moving cracks during the propagation process can be studied more accurately, scientifically and quantitatively.
Owner:CHINA UNIV OF MINING & TECH (BEIJING)
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