21 results about "Nominal stress" patented technology

The present application relates to a kind of pre-tensioned steel wire rope lateral impact response calculation method considering geometric and friction nonlinear coupling.First, the linear tensile constitutive model of pre-tensioned steel wire rope is constructed, Von Kármán large deflection theory is introduced, and the geometric hardening relationship of the nonlinear growth of axial tension with lateral deflection is established;Subsequently, a bilinear bending stiffness model is constructed to calculate the critical anti-sliding torque that evolves dynamically with tension;Based on the principle of energy conservation and Rayleigh-Ritz method, the system total potential energy functional of axial tensile potential energy and nonlinear bending potential energy is constructed, and the maximum impact deflection and tension response of the steel wire rope are obtained by solving the energy residual equation, the maximum response is substituted back into the constitutive equation, and the maximum nominal stress of the midspan cross section, the maximum axial tension and the extension length of the internal slip zone are calculated.The present application has very high calculation efficiency compared with full-size finite element simulation, and is suitable for the rapid design and safety evaluation of steel wire rope protection system.

The invention relates to a method for calculating the hot spot stress at the end part of a horizontal rod piece for supporting a transverse bulkhead, which belongs to the field of ship engineering structure design, and comprises the following steps of: calculating through a coarse mesh finite element to obtain node displacement, and determining the hot spot position at the end part of the rod piece; relative displacements of all the horizontal rod pieces are calculated, and then nominal stresses of all the horizontal rod pieces are calculated; or the nominal stress is obtained directly according to the coarse mesh finite element calculation result; combining each stress concentration coefficient corresponding to each hot spot; and calculating the hot spot stress. The invention provides a hot spot stress simplified calculation method based on a coarse grid calculation result (nominal stress) and a stress concentration coefficient, which is beneficial to improving the evaluation efficiency.

The application discloses a kind of wet clutch pressure and deformation relationship curve calculation method, according to the friction plate pressure-deformation relationship curve obtained from clutch friction plate compression performance test, based on the friction plate geometric parameter deduces the nominal stress-strain relationship curve of friction lining material, and it is separately endowed with friction lining structure;Steel sheet, friction lining, duplicate steel sheet are respectively endowed with the material mechanics attribute of itself, it can be applied to the case that the number proportion and volume proportion of arbitrary steel sheet, friction lining, duplicate steel sheet change;Friction lining is divided into different regions, define different material compression performance, the compression performance of friction lining material is corrected using finite element method, and the obtained material compression performance is more consistent with the actual;The compression performance parameters of friction lining material are obtained by adjusting Poisson's ratio using finite element technology, which is fast and accurate, can effectively shorten the compression performance test of substitute material, and further save the test cost.

The invention relates to the technical field of mechanical property testing, in particular to a laminated plate mechanical property evaluation method and system based on strain data. The method comprises the following steps: performing a biaxial tensile experiment on a laminated plate sample, synchronously acquiring load time-history data and a full-field speckle image, constructing a full-field strain matrix through a mapping algorithm, dispersing the full-field strain matrix into nodes, dividing a core pure shear region and a stress diffusion region, and then obtaining first principal strain through principal component analysis; a load transmission efficiency attenuation spectrum and full-field strain energy entropy density are calculated respectively, a dynamic correction model is constructed in combination with weighted coupling of preset shape characteristic parameters, and a real constitutive curve is obtained by using the model to calculate correction coefficient inversion nominal stress; the thermodynamic entropy characteristic is introduced, so that the problem that the stress field distortion at the nonlinear damage stage of the material is difficult to sense by a traditional method is solved, and the biaxial mechanical property test precision of the laminated plate is effectively improved.

The present invention relates to a method for testing the uniaxial creep threshold of a metal material, comprising: step 1, setting a nominal stress and performing a creep test on the metal material sample based on the nominal stress; step 2, if the creep strain within a preset time is greater than 1 / 10,000, reducing the nominal stress and re-performing the creep test for the preset time using a new sample; and re-performing step 2 or step 3; step 3, if the creep strain within the preset time is less than or equal to 1 / 10,000, increasing the nominal stress and continuing the creep test for the same preset time until the creep strain within the preset time is greater than 1 / 10,000, and then stopping the test; and step 4, obtaining the creep threshold of the sample. The present invention can quickly measure the uniaxial creep threshold of a metal material, saving testing costs.

This invention relates to the field of gear damage evaluation technology, specifically a method for evaluating the cohesive damage of laser cladding at the gear surface interface. The method includes the following steps: Real-time acquisition of normal and tangential strain data is achieved using a fiber optic grating sensor pre-placed at the interface between the cladding layer and the substrate. This data is then converted into real-time traction force values ​​based on the material's elastic constitutive relation, while simultaneously acquiring surface displacement data. A finite element model of the gear containing cohesive elements is constructed. Based on the traction separation constitutive relation and the second nominal stress criterion, the real-time traction force is introduced to drive the cohesive model for dynamic calculation, calculating the damage factor and determining the crack initiation state. This invention solves the prediction bias problem caused by the reliance on ideal assumptions in traditional cohesive models by deeply coupling real-time monitored physical quantities with numerical simulation, achieving early and accurate warning of cracks at the laser cladding layer interface. This significantly improves the real-time performance and reliability of damage evaluation, effectively avoiding engineering risks caused by sudden failures.

The present invention discloses a method for simultaneously predicting the tensile strength and fracture toughness of concrete based on cube splitting specimens, aiming to solve the technical problem in the prior art that it is impossible to simultaneously test and detect the tensile strength and fracture toughness of concrete based on the same cube splitting specimen. The main steps are as follows: casting cube splitting specimens of different sizes with a fixed water-cement ratio, maximum aggregate size d max and aggregate type, and the joint height ratio α by static loading test method until the specimen is damaged to obtain the peak load P max ; calculating the virtual crack length and nominal stress of the specimen σ n ; equivalent crack length a e ; substituting the σ n and a e calculated for specimens of different heights into #imgabs0# for regression analysis to obtain the tensile strength and fracture toughness of concrete. The prediction result of the method of the present invention has high accuracy, reasonable prediction method, low test cost, is simple and practical, and is convenient for popularization and application.

The systems and methods described herein are configured to use finite element (FE) stress calculations to estimate nominal stress without manual calculations, particular grid density requirements, or identification of particular geometric parameters, such as sheet thickness. The systems and methods described herein can be used to identify nominal stresses in welded structures and components, and also non-welded components having stress concentration due to other reasons. The systems and methods described herein also allow for utilization of readily available FE stress results in a consistent manner, as well as providing user feedback regarding the accuracy of nominal stress approximations. In addition, the systems and methods described herein are generally faster and less error-prone than conventional techniques, and are relatively insensitive to the grid density of FE stress calculations.

The present invention discloses a method for determining high stress volume under notch-defect interaction, which belongs to the technical field of damage tolerance assessment and fatigue strength prediction, comprising: calculating stress distribution data of the notch root in a component structure containing a defect notch by finite element analysis, and outputting the ratio of axial stress to nominal stress; calculating the virtual defect size of the notch component structure; using the critical distance method, combined with the ratio, calculating the stress concentration parameter of the notch root in the component structure containing the defect notch; and calculating the high stress volume area by analyzing the competitive effect of the notch and the defect, combined with the virtual defect size and stress concentration parameter. The present invention comprehensively considers the interaction between the notch and the defect, accurately calculates the high stress volume of the structure, helps to predict the fatigue failure site, and thus improves the accuracy of fatigue assessment. It is universal for structural parts with notches of any size and shape, is easy to operate, and has a wide range of applications.

The present application relates to the technical field of mechanical property testing, and more particularly to a method and system for evaluating the mechanical properties of a laminate based on strain data. The method comprises the following steps: performing a biaxial tensile test on a laminate sample, simultaneously collecting load time history data and full-field speckle images, constructing a full-field strain matrix and discretizing it into nodes using a mapping algorithm, dividing the core pure shear zone and stress diffusion zone, obtaining the first principal strain through principal component analysis, calculating the load transfer efficiency attenuation spectrum and the full-field strain energy entropy density, respectively, combining the preset shape feature parameters to construct a dynamic correction model, and using the model to calculate the correction coefficient to obtain the true constitutive curve by inverting the nominal stress. The introduction of thermodynamic entropy characteristics solves the problem of stress field distortion in the nonlinear damage stage that is difficult to perceive by traditional methods, effectively improving the accuracy of biaxial mechanical property testing of laminates.

This invention relates to the field of aero-engine technology, and discloses a method, system, and application for analyzing the crack propagation rate of high-temperature thin-walled plates. The method involves fracture surface analysis of the crack initiation zone at the test location of the thin-walled plate to obtain the initial crack propagation rate, followed by back-calculation of the first nominal stress of the thin-walled plate. Simulation analysis is then performed on thin-walled plates with and without initial cracks to obtain the stress distribution pattern, thereby extracting the second and third nominal stresses at the test location. The nominal stress is corrected for different crack lengths by combining the initial crack propagation rate and the corresponding nominal stress. Finally, the crack propagation rate for different crack lengths is calculated using a crack propagation model and material curves. This invention can provide support for predicting the subsequent crack propagation trend of thin-walled plates and provide a strong basis for determining the critical crack length of thin-walled plates.

The invention relates to a method for testing a uniaxial creep threshold value of a metal material, which comprises the following steps of: 1, setting nominal stress, and performing a creep test on a metal material sample based on the nominal stress; step 2, if the creep strain within the preset time is determined to be greater than 1 / 10000, reducing the nominal stress and adopting a new sample to perform the creep test for the preset time again; the step 2 or the step 3 is executed again; 3, determining that the creep strain in the preset time is less than or equal to 1 / 10000, increasing the nominal stress, continuing the creep test in the same preset time, and stopping the test until the creep strain in the preset time is greater than 1 / 10000; and step 4, obtaining the creep threshold value of the sample. According to the invention, the uniaxial creep threshold of the metal material can be rapidly measured, and the test cost is saved.

The application discloses a method and system for predicting the fatigue strength of a welded joint, and relates to the technical field of fatigue fracture of a material welded joint. The method comprises the following steps: obtaining the fatigue strength of a smooth sample; establishing a target finite element model based on the weld appearance of the welded joint, and obtaining the nonlinear stress distribution of the target position of the welded joint; determining the structural hot spot stress and the peak stress of the target position based on the nonlinear stress distribution of the target position; performing integral processing on the peak stress of the target position based on the critical distance of the notch of the welded joint, to obtain the peak hot spot stress of the target position; obtaining the effective notch stress of the target position based on the structural hot spot stress and the peak hot spot stress of the target position; determining the fatigue notch coefficient of the welded joint based on the effective notch stress of the target position and the nominal stress of the target finite element model; and obtaining the fatigue strength prediction value of the welded joint based on the fatigue notch coefficient of the welded joint and the fatigue strength of the smooth sample.

Systems and methods described herein are configured to control welding systems, for example, controlling welding process variables based at least in part on nominal stresses estimated using finite element (FE) algorithms. The systems and methods described herein may be utilized to identify nominal stress in welded structures and components to enable adjustment of welding process variables for the manufacture of subsequent welded structures and components, for example, performed by the same welding system. The systems and methods described herein also allow readily available FE stress results to be utilized in a consistent manner, as well as providing user feedback regarding the accuracy of the nominal stress approximations. Furthermore, the systems and methods described herein are generally faster and less error prone than conventional techniques, and are relatively insensitive to mesh density of the FE stress calculations.

The invention relates to the technical field of aero-engines, and discloses a method and a system for evaluating the service life of a rotor connecting bolt, and the method comprises the steps: comprehensively considering the stress concentration coefficient of the connecting bolt and the nominal stress of a thread tooth of the connecting bolt under a working load; according to the method and the device, the weak part of the connecting bolt can be accurately identified according to the load conditions of the axial matching end surfaces of the connected pieces and the load conditions of the axial matching end surfaces of the connected pieces under the standard contact condition and the non-separated contact condition, the accurate analysis of the high-cycle fatigue reserve coefficient of the connecting bolt can be better guided, and the evaluation of the high-cycle fatigue life of the connecting bolt can be realized. According to the method, the risk of high-cycle fatigue failure of the rotor connecting bolt can be effectively avoided, and support is provided for safety and reliability of the rotor connecting bolt in the service life.

The invention relates to the technical field of aero-engines, and discloses a high-temperature thin-wall plate crack growth rate analysis method and system and application, fracture analysis is carried out on a crack source area at an examination position of a thin-wall plate, the initial crack growth rate of a crack is obtained, and then the first nominal stress of the thin-wall plate is inversely calculated; carrying out simulation analysis on the thin-wall plate with the initial crack and without the initial crack to obtain a stress distribution form of the thin-wall plate so as to extract a second nominal stress and a third nominal stress of the examination part; correcting the nominal stress under different crack lengths by combining the initial crack propagation rate and the corresponding nominal stress; and finally, calculating through the crack propagation model and the material curve to obtain crack propagation rates under different cracks. According to the method, support can be provided for subsequent crack propagation trend prediction of the thin-wall plate, and a powerful basis can be provided for determination of the critical crack length of the thin-wall plate.

The invention discloses a multi-axis creep equivalent acceleration spectrum compilation method, and belongs to the technical field of high-temperature structural strength and integrity. Through a high-temperature creep test of a smooth material test piece and a two-stage variable-temperature variable-load test of the smooth material test piece, the bone point position and the bone point stress at the minimum cross section of a notched round rod are calculated based on a bone point stress method, and the uniaxial creep representative stress corresponding to each stage of nominal stress of a notched sample is obtained; and according to a uniaxial creep load nonlinear damage accumulation model, converting the multi-stage representative stress creep load spectrum into an equivalent acceleration spectrum of a first-stage maximum creep load based on a damage consistency principle, and finally obtaining a creep equivalent acceleration spectrum of the notched sample according to the notched sample nominal stress corresponding to the maximum first-stage uniaxial creep representative stress. According to the method, the multi-axis creep load can be converted into a large creep load state according to a damage equivalence principle, so that the multi-axis creep test time is greatly saved.

The present invention relates to the technical field of fatigue analysis of floating body structures, and specifically discloses a method and system for fatigue damage analysis of a floating wind turbine floating body structure. The method includes: constructing a model of the floating wind turbine; obtaining the response of the wind load acting on the structural cross-section of the floating body structure under different wind conditions only considering the action of wind; under the condition of the wind turbine being shut down, obtaining the response of the wave load acting on the structural cross-section under different wave actions only considering the action of waves; obtaining the total load response at the structural cross-section under the corresponding marine environmental conditions; converting the total load response into local nominal stress; calculating the short-term fatigue damage under the corresponding marine environmental conditions; and calculating the long-term fatigue damage. The present invention solves the problems of large computational amount and long calculation time brought by the existing fully coupled time-domain analysis, improves the fatigue analysis efficiency while ensuring the calculation accuracy, and can quickly and accurately perform long-term fatigue assessment in engineering applications.

The present invention discloses a method for simultaneously predicting the tensile strength and fracture toughness of concrete based on a diagonal cube splitting specimen, aiming to solve the technical problem in the prior art that it is impossible to simultaneously test and detect the tensile strength and fracture toughness of concrete based on the same diagonal cube splitting specimen. Its main steps are as follows: casting diagonal cube splitting specimens of different sizes with a fixed water-cement ratio, maximum aggregate size d max and aggregate type, and the joint height ratio α by static loading test method until the specimen is damaged to obtain the peak load P max ; calculating the virtual crack length and nominal stress of the specimen σ n ; equivalent crack length a e ; substituting the σ n and a e calculated for specimens of different heights into #imgabs0# for regression analysis to obtain the tensile strength and fracture toughness of the concrete. The prediction result of the method of the present invention has high accuracy, reasonable prediction method, low test cost, is simple and practical, and is convenient for popularization and application.

Systems and methods described herein are configured to estimate nominal stress using finite element (FE) stress calculations, without hand calculations, specific mesh density requirements, or identifying specific geometric parameters such as plate thickness. The systems and methods described herein may be utilized to identify nominal stress in welded structures and components, and also in non-welded components that have stress raisers due to other causes. The systems and methods described herein also allow readily available FE stress results to be utilized in a consistent manner, as well as providing user feedback regarding the accuracy of the nominal stress approximations. Furthermore, the systems and methods described herein are generally faster and less error prone than conventional techniques, and are relatively insensitive to mesh density of the FE stress calculations.

The invention provides an additive manufacturing metal part key defect identification method based on defect geometrical characteristics, and relates to the technical field of additive manufacturing fatigue performance evaluation, and the method achieves the purpose of identifying the key defect of an additive manufacturing metal part from the traditional XCT which can only identify the existence of the defect by constructing a fatigue damage parameter model fusing the defect geometrical characteristics and a service load. Therefore, the most dangerous defect can be accurately evaluated, and the problem of lack of quantitative evaluation of defect risk in the prior art is overcome. By establishing a fatigue damage parameter model, fatigue damage parameters of all defects are calculated and sorted by using nominal stress of all the defects and target geometrical characteristic parameters of all the defects extracted based on a two-dimensional slice image, so that critical defects are scientifically identified; the fatigue reliability evaluation precision of the additive manufacturing metal part under the actual working condition is remarkably improved, and a quantifiable and operable technical basis is provided for quality control and life prediction.