368 results about "Finite element approach" patented technology

The invention discloses a method for accurately calculating a temperature field in an oil-immersed transformer. According to the method, a 3D physical model which completely corresponds to a real transformer in size and structure is built, scientific mesh generation is carried out on the physical model according to different characteristics of calculation methods, a finite volume method and a finite element method are combined for calculation, in other words, the finite volume method is used for calculating metal heat conduction of a winding and iron core portion and heat transfer in which fluid participates, and the accurate 3D calculation result of the temperature field in the oil-immersed transformer can be obtained; not only the temperature field of a winding or an iron core but also the temperature field of oil flow in the transformer, the temperature field of cooling fins and the temperature field of a transformer box can be accurately calculated, and the method has important and comprehensive referential significance in both design of transformers and actual operation of the transformers.

The invention relates to a probabilistic finite element method (PFEM)-based steel-bride fatigue reliability evaluation method, in particular to a fatigue reliability evaluation method by combining dynamic weighing data (WIM) of a car and the analysis of the PFEM, which aims at solving the problems that the bridge structure health monitoring cost is higher and the stress measuring point distribution is limited, and utilizes the real WIM data to statistically analyze car load and establishes a probabilistic distribution model of a car type, road distribution, axle weight and wheel-base. Finite element method analysis software is used for establishing a numeric model of a bridge. A probabilistic finite element program is compiled, stress amplitude and stress cyclic quantity of a key part under the random car load effect are extracted through the sampling, loading and finite element analysis to be statistically counted. The fatigue reliability calculation is performed according to the statistical result, and the reliability attenuation trend of the evaluated part in the subsequent application process is predicted. By adopting the method, a feasible analysis tool is provided for the fine fatigue evaluation of complicated steel-bridge details.

Systems and methods of computer aided engineering analysis using hybrid approach of finite element method (FEM) and adaptive smoothed particle hydrodynamics (SPH) are described. According to one aspect, a computer-aided engineering analysis is performed to simulate an impact event between structures. A FEM grid model is created to represent the structures using a plurality of solid elements which represents geometry and material properties. Once a contact between two structures resulted into a material or structural failure according to predefined material constitutive equation, solid elements representing the failed portion of the structure are removed. Each failed solid element is then replaced by a plurality of particles to be analyzed using the SPH analysis. The particles replacing the failed element inherit all of the states and properties of the failed element, such as location, mass, velocity, acceleration, etc. The replacement is conducted according to the principles of mass, momentum and energy conservation.

A method for determining the time-varying reliability of prestressed concrete box girder bridges based on the stochastic finite element method. For prestressed concrete box girders that are widely used in highway bridge systems and have common early-stage diseases, by combining degenerate shell elements, material constitutive relations and The crack model simulates the nonlinear characteristics of the box girder in the cracking stage, and the embedded concrete creep, shrinkage and steel strand stress relaxation model considers the deformation, prestress loss and internal force redistribution of the box girder during its entire life, through the reinforcement The uniform corrosion model and the pitting corrosion model calculate the section loss of steel bars (steel strands) in carbonization environment and chloride ion environment respectively. Finally, through the definition of random variables, sampling, calling finite element program calculation and extracting stress and strain results, the reliability calculation of the box girder bridge is realized and used to guide the subsequent maintenance and reinforcement work.

The invention provides a numerical simulation analysis method for multi-field coupling of a loudspeaker. The method includes: firstly, establishing a finite element model, to be more specific, (1) establishing a physical model, namely adding corresponding physical fields and adding a solving step according to different structures of the loudspeaker and different physical principles referred in different working stages, (2) establishing a geometric model, (3) defining material properties, modifying the physical fields and defining boundary conditions, load and the like, (4) performing meshing on the model; secondly, performing solving and post-processing, to be more specific, solving the established model via a finite element method, and subjecting results to post-processing to finally obtain loudspeaker characteristic parameters under mutual influences among the different physical fields, wherein the loudspeaker characteristic parameters include loudspeaker electromagnetic characteristics such as Bl(x) and Z(f), structural mechanical characteristics such as f0 and K(x) of a loudspeaker vibration system, loudspeaker acoustic characteristics of SPL, directivity curves and the like and temperature field characteristics and the like of the loudspeaker. In the process of establishing the finite element model, the material properties of variation with temperature and the special boundary conditions and load modes are defined to couple the different physical fields.

Disclosed is a junction surface contact area and rigidity confirming method based on surface fitting. The junction surface contact area and rigidity confirming method based on the surface fitting includes: firstly, using confocal microscopy and three coordinate measuring to measure micro bulge morphology, external waviness and shape error of a mechanical junction surface, performing fitting on obtained point cloud data by using a binary high order function, and accordingly obtaining a final analysis formula of a contact surface; secondly, judging positions and contact directions of micro bulge contact points, then performing Hertz contact calculation on each single contact point, and calculating contact deformation and contact area under functions of force; finally, calculating overall contact area and contact rigidity of the contact surface so as to obtain total contact area and contact rigidity in each direction. Compared with a traditional analysis method, the junction surface contact area and rigidity confirming method based on the surface fitting has the advantage of approaching real morphology. Compared with a finite element method, the junction surface contact area and rigidity confirming method based on the surface fitting can enlarge the contact area which can be calculated.

A method for analyzing a structure includes processing nondestructive inspection (NDI) data for a multi-layer structure to define areas of inconsistency at an internal layer or an interface between adjacent layers. The method includes mapping the areas of inconsistency to finite elements of a finite element model of a nominal of the structure. These finite elements are thereby identified as affected finite elements and include finite elements for the affected internal layer or interface. The method includes producing a reconstructed finite element model of the affected structure from the nominal finite element model, and a modified property or state value assigned to respective element datasets of the affected finite elements. The method includes performing a finite element method (FEM) failure analysis of the reconstructed finite element model under a load, which indicates an extent of residual integrity of the affected structure.

The invention relates to a method for predicting welding deformation of a large radar structural part. The method comprises the steps of adopting a large radar structural part welding process to select an appropriate welding experiment board and a strain piece and adopting a blind hole method to extract the deformation amount in the welding process; performing modeling and grid dividing on the experiment board and the large structural part; adopting a thermo-elastic finite element method to preliminarily determine the welding deformation amount of a test part, comparing the welding deformation amount with a measured value and enabling an error to be smaller than 15% according to the fine adjustment boundary condition and the clamping condition; adopting an inherent strain method to directly load the deformation amount obtained through experiment board calculation to the welding deformation calculation of the large structural part, and finishing prediction on the welding deformation of the large structural part. The method adopts a small amount of process tests and combines with the inherent strain method to achieve quantitative prediction on the welding deformation of the large radar structural part and deformation trend analysis, the test cost of the large structural part welding process is reduced, the test working amount and the analog calculation amount are decreased, and the method has guiding significance on radar welding production.

The invention relates to a complex space curved surface thin plate forming die face designing method taking springback compensation. The method includes using a finite element method to simulate a plate forming process by taking ideal product appearance as a die face to acquire stress matrix of a punched plate node; using a modified forward rebound method for iterative solving to acquire compensation displacement matrix of a curved surface node; using a modified body deformation method to fit a node to acquire a curved surface after compensation, and constantly repeating the above process until the die face can pun qualified products. In order to increase compensation speed, the forward rebound method is modified, so that calculated quantity of iteration of each time is reduced; reconstruction from points to the complex curved surface is realized in iterative steps. By a modified body deformation algorithm, the advantage of smoothness of the curved surface constructed by the body deformation algorithm is maintained while calculated quantity is reduced, and quick designing of rebound compensation die faces is realized.

The invention discloses an intelligent early warning and forecasting method for soil slope dangerous situations. , belongs to the technical field of geology, and aims to provide an intelligent early warning and forecasting method for soil slope dangerous situations, which can accurately forecast soil slope dangerous situations, and is characterized by comprising the following steps: S1, selectinga monitored slope area, and dividing a slope into a plurality of monitoring areas according to a finite element method; S2, establishing an information acquisition system and a dangerous case prediction system, and acquiring the height, gradient and area of the monitored area through the information acquisition system; and S3, enabling the information acquisition system to send the monitoring areas to the dangerous case prediction system in a wireless mode. A soil permeameter and a displacement meter acquire the soil permeability and the soil displacement of the monitoring areas in real time;the information obtaining system obtains the heights, gradients and areas of the monitoring areas in real time, then a three-dimensional model is established through the dangerous case prediction system, the three-dimensional model obtains various parameters in real time, the slope is dynamically predicted, and prediction of the possibility of slope landslide is more accurate.

The invention discloses a method for calculating underground water seepage flow based on an equipotential surface. The method comprising the following steps: (1.1) solving a seepage field, namely solving the seepage field by adopting the conventional finite element method and solving the water head values of the nodes of each unit; (1.2) determining the water head value of the equipotential surface, defining the water head value of the equipotential surface to be determined as h0, and forming the equipotential surface by the nodes with the same water head value; and (1.3) executing the step (1.3.1) on any unit or a unit No. ie in the seepage field, wherein the step (1.3.1) includes that the relations between the water head values of the nodes and h0 are judged. The method disclosed by the invention is a new method which solves the underground water seepage flow by utilizing a finite element and has the advantages that integral is directly carried out on the equipotential surface, the section through which water flows is vertical to the flow direction, no component interference is produced and calculation accuracy is high. The flow passing through the equipotential surface of the water head is in just one direction, thus avoiding that not only the direction of gradient of the water head but also the direction of an area vector are required to be determined in a middle section method.

The invention discloses an air-gap asymmetrical switched reluctance linear motor magnetic path modeling method, particularly applicable to switched reluctance linear motors of various phase number structures and belongs to the field of switched reluctance linear motor establishing and control.The air-gap asymmetrical switched reluctance linear motor magnetic path modeling method is characterized in that a magnetic path model of an air-gap asymmetrical switched reluctance linear motor is formed by combining all calculation formulas of reluctance components in four magnetic paths at the active cell position xu where the central line of an active cell groove of the switched reluctance linear motor is aligned to the central line of stator teeth, the active cell position x0 where the front edges of active cell teeth are aligned to the front edges of the stator teeth, the active cell position x1/2 where the active cell teeth are overlapped with the stator teeth for one half of the width of the stator teeth, and the active cell position xa where the central line of the active cell teeth is aligned to the central line of the stator teeth without magnetic characteristic calculation performed by adopting a motor electromagnetic field finite element method.The method is quick in calculation, is suitable for the air-gap asymmetrical switched reluctance linear motors of various phase number structures, can achieve systematic and quick design, real-time simulation and real-time control of the air-gap asymmetrical switched reluctance linear motors and has a good engineering application value.

The invention discloses a semi-active shock absorption controlling device and method for a large aqueduct under longitudinal shock input. The method comprises the steps that a magneto-rheological damper is used as a controller; a spencer model of the magneto-rheological damper is used to simulate shock absorption; an LQR/LQG control law is used to design active control, and the optimal state feedback gain is obtained in an LQR method; the magneto-rheological damper is combined with an aqueduct structure so that the semi-active control device achieves an optimal active control force approximately, and a semi-active control law is designed; the space dynamic force of the aqueduct structure is calculated in a beam segment finite element method; and in the process of tentative calculation of the optimal control force, the form and size of weight matrixes Q and R are continuously adjusted to obtain the active control force through which control effect and force are comprehensively optimal. The device comprises an aqueduct body, a support, a basin type rubber bearer, a lead-core rubber bearer, a dilatation joint, the magneto-rheological damper and a pier top. The method and structure are simple, the dynamic scope is wide, the endurance is high, and the damping force can be continuously adjusted.

The embodiment of the invention discloses a field circuit coupling method and device for a direct-current electric field of a multi-layer integrated circuit. The method comprises: acquiring a multilayer integrated circuit direct-current electric field two-dimensional model simplified according to a three-dimensional model of a multilayer integrated circuit direct-current electric field, establishing a field domain solving equation set for the two-dimensional model of each layer through a finite element method, and forming an overall sparse matrix of the integrated circuit field domain solvingequation set; for an external circuit of the integrated circuit, establishing a symmetric positive definite external circuit equation set according to a super-node method; and combining the field domain solving equation set with the external circuit equation set, establishing a symmetrical positive definite unified solving equation set of field-circuit coupling, combining the equation sets by scanning the super nodes, and ending scanning if all the super nodes are scanned. Field circuit coupling can be accurately and completely carried out on the multi-layer integrated circuit direct-current electric field, and the design effect of multi-layer integrated circuit and chip packaging is improved.

The invention aims to provide a simulation method for obtaining hot spot temperatures of a power transformer under different working conditions. Based on the actual structure of an oil-immersed transformer, a three-dimensional simulation model of the temperature rise of the transformer is established by adopting a method of combining a finite element and a finite volume method, the influence of factors such as an electromagnetic field and oil flow on the temperature is considered, and the simulation of the hot-spot temperature distribution of the transformer is realized. The method comprises the following steps: S1, establishing a three-dimensional physical model of the power transformer; s2, performing theoretical analysis of electromagnetic field calculation of the power transformer; s3,calculating theoretical analysis of the fluid and the thermal field of the power transformer; s4, adding a corresponding physical field based on theoretical analysis of the electromagnetic field andfluid-solid heat; s5, performing field-circuit coupling connection under different working conditions according to actual operation conditions, and setting parameters and boundary conditions; s6, performing multi-physical field coupling setting; and S7, performing mesh generation on the model based on a finite element method, and performing simulation to obtain temperature distribution and hot spot temperature position results of the power transformer under different working conditions.

The invention provides a two-dimensional rapid iteration method for electromagnetic response of a three-dimensional large-scale integrated circuit. The two-dimensional rapid iteration method comprises the following steps: 1, dividing each layer of integrated circuit layout with a complex shape into polygons with simple shapes; 2, taking the influence of other layers as an additional source, and calculating the electromagnetic field and surface current distribution of each layer of the integrated circuit layout through a two-dimensional finite element method; 3, calculating the influence of the non-uniformly distributed surface current on the simple-shaped polygon on the field points through two-dimensional Gaussian integral based on a vector Green function of the influence of a point current source on the field points, and further calculating the influence of the non-uniformly distributed surface current on the complex-shaped integrated circuit layout on the electromagnetic field distribution of all other layers; and 4, judging whether the change quantity of the electromagnetic field distribution of all layers is smaller than a preset error threshold value or not, if yes, ending, and if not, turning to the step 2. The invention further provides a device of the method, and the electromagnetic response on the three-dimensional integrated circuit layout can be rapidly calculated through two-dimensional iteration.

The invention discloses a high-frequency seismic wave scattering simulating method based on a fast multipole indirect boundary element method. By combining a fast multipole method (FMM) and an indirect boundary element method (IBEM), the fast multipole indirect boundary element method based on diagonal plane wave expansion is given. According to the method, the high-frequency seismic wave scattering problem which cannot be solved through other methods (such as an analytical method, a finite difference method, a finite element method and a general boundary element method) can be quickly solved, hundreds of thousands of three-dimensional scattering problems can be completed in an ordinary personal computer, an effective method is supplied to high-frequency or large-scale seismic wave scattering simulating, computer resource occupying is greatly reduced while the calculating speed is improved, and the remarkable economic benefits are brought to fast simulating of practical engineering.

The invention discloses a hot-rolling working roll temperature distribution obtaining method. The method comprises the steps that the arrangement form of a hot-rolling working roll cooling injection system is constructed; a working roll heat exchange area is divided according to the arrangement form of the working roll cooling injection system; rolling process parameters and thermophysical parameters, including working roll parameters, rolled piece parameters, medium parameters and heat exchange coefficients, are acquired; axial-radial section grid nodes of the working roll are divided, and coordinate system parameters and a temperature calculation model of each node are established; a temperature calculation model is utilized, the heat exchange area where the section of the working roll is located is judged firstly every time calculation is conducted from the initial calculation position to the final calculation position, and then the temperature distribution of the section of the working roll at the position is calculated through a corresponding working roll temperature model. The method has the beneficial effects that the method is clear and definite, assumption and simplification conditions are few, the temperature field change of the working roll in the hot rolling process can be accurately forecasted, the calculation precision is higher than that of an analytical method,and the calculation speed is higher than that of a finite element method.

The coupling of geomechanics to reservoir simulation is essential for many practical situations in the exploitation of hydrocarbons. Such coupling requires cross-mapping block-centered data in reservoir model to nodal data in geomechanical finite element model. If different grid geometries and grid densities between two models are used, this data mapping will become considerably challenging. In this invention, an innovative method is proposed to achieve remarkable accuracy of data mapping from reservoir model to the geomechanical model with ease and quite efficiently using least squares finite element method. The achievement of accurate data mapping will enable efficient simulation coupling between reservoir simulation and geomechanical simulation to investigate some engineering problems in the exploitation of hydrocarbons.

The invention provides a ship free field underwater acoustic radiation far field criterion method. The method comprises the steps that a ship drawing is used for establishing a whole ship and surrounding fluid finite element model; Obtaining input excitation for calculating the vibration response of the whole ship; Calculating a vibration wet mode of the ship body by using a finite element method,and calculating a vibration response of the whole ship based on a mode superposition method; Establishing a ship acoustic radiation calculation boundary element model; Mapping the vibration velocityinterpolation of the wet water surface shell of the ship body into a boundary element grid to serve as a boundary condition of ship underwater acoustic radiation calculation; Establishing ship underwater acoustic radiation directivity field points under different water depths and radiation radiuses, and calculating acoustic radiation directivity of the ship under different frequencies by utilizinga boundary element method; And analyzing the acoustic radiation directivity of the ship, and judging the underwater acoustic radiation far-field distance of the ship. The acoustic radiation directivity is used as a ship far-field criterion method, and the method has good intuitiveness and can be applied to underwater acoustic radiation far-field criteria of various ships and submarines.

The invention discloses a shale gas reservoir fractured horizontal well yield prediction method based on a random fractured model, and belongs to the technical field of oil and gas reservoir development. A natural fractured model conforming to probability distribution and statistical rules is established based on a Monte Carlo random fracture algorithm. The defect that a traditional continuous medium model is difficult to describe natural fracture properties and spatial distribution differences is overcome, and real distribution characteristics and flow rules of natural fractures in a shale reservoir are effectively represented. According to the shale gas reservoir fractured horizontal well yield prediction method based on the random fractured model, a finite element method and a non-structural Delaunay triangular mesh are combined to establish a fully implicit numerical model, and accurate prediction of the yield of the complex fracture network fractured horizontal well in the shale gas reservoir is achieved.