24 results about "Boundary element method" patented technology

The invention relates to the technical field of numerical simulation ship response, in particular to a ship hydrodynamic response numerical simulation method and system considering the effects of a complex wave field and an automatic mooring system. Firstly, ship radiation potential and hydrodynamic coefficients are obtained based on a three-dimensional potential flow theory and a boundary element method, and wave field information at a berth is obtained in combination with a Boussinesq wave theory; the time domain wave force is solved through the Haskind-Relation theory, and an automatic mooring numerical model integrated with a PD controller is established to calculate the automatic mooring force and torque; and finally, constructing a ship six-degree-of-freedom time domain motion equation based on the data, and solving by adopting a four-order Runge-Kutta method to obtain a time domain response result. The hybrid Boussinesq-Panel technology is adopted, the wave disturbance evaluation accuracy is improved, the blank that existing simulation does not consider an automatic mooring system sufficiently is filled up, arrangement, parameters and control strategies of the automatic mooring device can be flexibly adjusted and secondarily developed, applicability and flexibility are high, and the method is suitable for large-scale popularization and application. And reliable decision support can be provided for procurement and deployment of automatic mooring equipment of a port.

The invention provides a three-dimensional water elasticity response calculation method based on boundary element-explicit finite element coupling, and belongs to the technical field of water elasticity response calculation based on computer data processing. The wave evolution of a fluid domain is solved by adopting a boundary element method, and the dynamic response of the elastic plate is solved by adopting an explicit finite element method. Inspired by an implicit boundary condition method of a wave-rigid body coupling effect, an explicit dynamic control equation of a structural domain elastic plate is substituted into a boundary condition met by an object plane acceleration potential of a fluid domain elastic plate, and an additional relation between an elastic plate surface fluid velocity potential time derivative and a normal derivative of the elastic plate surface fluid velocity potential time derivative is established; the implicit boundary condition is satisfied by the surface of the elastic plate. The deduced implicit boundary condition and the satisfied Laplacian equation are combined, and the value of the surface of the elastic plate can be accurately obtained. According to the three-dimensional time domain numerical method for wave-elastic plate coupling provided by the invention, stable and accurate calculation of wave load and structural response can be realized.

The invention belongs to the technical field of feature recognition of underwater complex targets, and relates to a boundary element-based multi-bright-spot cluster target interference feature estimation method, which comprises the steps of geometric model construction and introduction, numerical calculation based on multi-physics field coupling, echo intensity representation by adopting an angle-frequency spectrum, and analysis of resonance generated by multi-body interference. According to the method, a numerical model for solving a three-dimensional double-gas-cylinder omnidirectional scattering sound field is established based on a boundary element method, and omnidirectional and broadband scattering characteristics of a target in horizontal and vertical attitudes are calculated; a multi-bright-spot dual-target strong scattering coupling mechanism is mainly analyzed, and a multi-body configuration and single target scattering interference fringe generation mechanism is disclosed; according to the method, the inherent attribute characteristics of the single target can still be effectively identified in a cluster target scattering field; the mapping relation among the geometric configuration, the spatial arrangement mode and the frequency response is obtained, and a theoretical formula suitable for double-target sound scattering forecast is deduced.

The invention discloses a subway vibration response layered medium domain coupling analysis method based on a time domain boundary element method, and the method comprises the steps: building a boundary node coordinate matrix, an internal node coordinate matrix and a unit positioning matrix of each sub-domain based on the material parameters of a soil layer, subway vibration load numerical simulation data and load action time; generating a common boundary node relation matrix based on the boundary node coordinate matrix and a common boundary condition; calculating a unit influence coefficient matrix of each sub-domain based on the unit positioning matrix and the material parameters, and correcting the unit influence coefficient matrix of each sub-domain to obtain a corrected unit influence coefficient matrix of each sub-domain; based on the corrected influence coefficient matrix of each sub-domain unit, assembling to form an overall influence coefficient matrix; based on the common boundary node relation matrix and the overall influence coefficient matrix, displacement and surface force of boundary points are obtained through solving; and calculating displacement and stress of the internal nodes based on the internal node coordinate matrix and the internal node influence coefficient matrix.

The application provides a substation steel structure earthquake risk early warning method and device, equipment and medium, and the method comprises the steps of: constructing a foundation soil-substation steel structure model and a half-space site model; based on an indirect boundary element method, simulating the seismic response according to the half-space site model and the foundation soil-substation steel structure model to determine a risk grade early warning table; acquiring a target displacement response of the substation steel structure in real time; and analyzing the target displacement response and the risk grade early warning table to determine the seismic risk grade of the current substation steel structure. The application simulates and calculates the displacement response of the substation steel structure under different seismic risk grades based on the indirect boundary element method, the half-space site model and the foundation soil-substation steel structure model, can automatically meet the infinite boundary condition, reduces the problem dimension, improves the solving accuracy, thereby obtains more accurate seismic response of the substation steel structure, and can accurately monitor the risk grade of the substation steel structure.

The invention provides a finite element and time domain boundary element full time domain inter-system iterative coupling method. The method comprises the following steps: splitting a coupling system into an FEM sub-domain and a TDBEM sub-domain; carrying out discrete processing on the FEM sub-domain and the TDBEM sub-domain; applying the interface variable of the TDBEM sub-domain of the previous iteration to the FEM sub-domain as a boundary condition, completing dynamic response calculation of all time steps at one time in the full time domain through a finite element method, and extracting the interface variable of the FEM sub-domain; applying the interface variable of the FEM sub-domain as a boundary condition to the TDBEM sub-domain, completing fluctuation response calculation of all time steps in a full time domain at one time through a time domain boundary element method, and extracting the interface variable of the TDBEM sub-domain; and performing convergence judgment based on the interface variable shift. The method is used for solving the problems that an existing coupling method is low in calculation efficiency, insufficient in flexibility / universality and low in engineering practicability.

The application discloses a closed space transient sound field simulation method based on modal expansion. The wave equation is solved based on the modal expansion theory, and finally the sound field is represented as superposition of a series of sound modes, that is, represented as a linear combination of the product of modal expansion coefficients and characteristic functions, wherein the modal expansion coefficients are quantities related to time information, and the characteristic functions are quantities related to space information. The application establishes a calculation format fusing boundaries and internal spaces based on the decomposition of the time-domain wave equation, thereby avoiding the large calculation amount problem of the traditional finite difference method in time and space. A time scale stable model is established through the solution of the transient modal expansion coefficient, thereby avoiding the instability problem of the time-domain boundary element method in the time scale. The application realizes efficient and accurate simulation of the closed space transient sound field through accurate modeling of the propagation and attenuation process of the sound field in the closed space.

The invention discloses an elevated station under-bridge waiting hall vehicle-induced structural noise parameterization calculation method, which is characterized by comprising the following steps: S1, dividing the top surface of an elevated station under-bridge waiting hall into areas, acquiring the area of each area, the coordinates of a central point and the time domain vibration acceleration of each central point, and further obtaining the vibration speed; s2, establishing a relationship between the vibration speed and the radiation sound power, and converting the vibration quantity into an acoustic quantity; s3, establishing a relationship between the radiation sound power of each region and the sound pressure radiated to the target point in each region; s4, superposing the sound pressure contributions of the full frequency band and all the areas to obtain total sound pressure; and S5, calculating the structural noise sound pressure level of the target point. Compared with a traditional finite element method and a boundary element method, the method has the advantages that the calculation complexity is remarkably reduced, the efficiency is greatly improved, the full-band calculation precision is improved, the data acquisition threshold is low, and the design period is shortened.

This invention proposes a wavefield calculation method and system coupled with finite element method and artificial boundary, relating to the field of seismic resistance technology for underground structures. Addressing the problems of spurious reflections easily generated by artificial boundaries in the finite element method, low computational efficiency of the boundary element method, difficulty in handling material nonlinearities, and coupling difficulties, this invention divides the computational domain into an outer infinite domain and an inner finite domain. The outer infinite domain is solved using the fast multipole boundary element method to obtain wavefield data of the artificial boundary. The wavefield data is then transformed into equivalent nodal forces on the boundary nodes of the inner finite domain using the artificial boundary substructure method. The finite element method is then used to perform nonlinear dynamic response analysis on the inner finite domain under the applied equivalent nodal forces. This overcomes the shortcomings of low computational efficiency and difficulty in handling nonlinearities, while retaining the ability of the finite element method to handle complex nonlinearities. It achieves a balance between high accuracy and high computational efficiency, improving the stability and reliability of seismic dynamic response analysis.

The invention relates to an air ultrasonic touch fingertip skin mechanical simulation method based on time domain BEM-FEM coupling, and belongs to the technical field of man-machine interaction and touch rendering. The method comprises the steps of constructing a piezoelectric ultrasonic transducer PUT array time domain sound field model, calculating focused ultrasonic waves of a PUT array in a free field and time domain sound field distribution of the focused ultrasonic waves, constructing a rigid body surface sound scattering model based on a time domain boundary element method BEM, and calculating synthetic ultrasonic waves after the focused ultrasonic waves are incident to the rigid body surface and time domain total sound field distribution of the synthetic ultrasonic waves; applying the solved time domain total sound field to sound radiation pressure ARP calculation; a three-dimensional fingertip model with a multilayer anatomical structure is established, and skin deformation of finger skin under air ultrasonic tactile stimulation is solved based on a finite element method FEM. The method has the advantages that mapping from driving waveform design of the air ultrasonic tactile device to finger skin deformation is achieved, and an efficient simulation method is provided for complex air ultrasonic tactile rendering.

The application provides a kind of ellipsoidal liquid storage device with grating and its mechanical property simulation method, and the liquid storage structure includes: liquid tank body and the grating for dissipating sloshing energy arranged inside the liquid tank body, the liquid tank body and the grating are all spatial axisymmetric ellipsoids, a plurality of through holes are arranged on the grating and connected with the internal volume of the grating, and the porosity of the through holes is uniform; the upper part of the liquid tank body is provided with a liquid inlet; the lower part of the liquid tank body is provided with a liquid outlet; the mechanical property simulation method adopts three-dimensional axisymmetric liquid sloshing analysis satisfying Laplace equation to be reduced to two-dimensional solution, then the discrete equation of the meridian plane boundary is obtained, and the axisymmetric equal-geometry boundary element method matrix equation of axisymmetric liquid sloshing is obtained, and based on the axisymmetric equal-geometry boundary element method matrix equation, the dynamic water pressure p of the liquid storage device, the liquid surface elevation η, and the x-direction sloshing force are obtained; the liquid storage device has simple structure and good sloshing reduction effect; the stress calculation method has high accuracy and high efficiency.

The invention provides a three-dimensional underground heterogeneous body inversion method and device and a storage medium, and relates to the field of geological prospecting, and the method comprises the steps: building an observation region coordinate system, recording the coordinates of a load point and the coordinates of an observation point in the coordinate system, and obtaining the observation displacement amplitude of the observation point under the action of a surface simple harmonic concentrated load; determining a parameter search range according to the geological data; model parameters are set and updated through a multi-strategy dung beetle optimization algorithm; performing forward modeling simulation on the model through an indirect boundary element method only needing boundary discretization to obtain a surface displacement amplitude; constructing a fitness function, and calculating the fitness value of the observation displacement amplitude and the earth surface displacement amplitude; and judging whether the fitness value meets the fitness requirement of iteration termination or not. According to the method, the problems that high-dimensional parameter coupling is difficult to process, an inversion result is not unique and forward modeling calculation efficiency is low in a traditional method are solved, and an accurate and efficient solution is provided for engineering geology problems such as underground cavity positioning and karst collapse risk assessment.

The invention discloses an unsteady aerodynamic force calculation and optimization method for a wind turbine blade. The method is based on a potential flow theory, a Laplacian control equation is established, corresponding boundary conditions are set, and a wind turbine geometric model composed of a plurality of airfoils is imported; dispersing the surface of the blade into vortex grids formed by vortex lines by adopting a boundary element method, solving a linear matrix to obtain vortex intensity by distributing initial vortex intensity, and iteratively calculating a velocity field and a pressure field according to the Biot-Savart law; and the aerodynamic force and energy output coefficient of the blade is calculated based on the Kutta-like Kovski theorem, and nonlinear correction is carried out through comparison with experimental data, so that the calculation precision is ensured. According to the method, the calculation efficiency and accuracy are considered, the precision is superior to the blade element momentum theory, the calculation resource consumption is lower than that of a computational fluid mechanics method, and the method is suitable for aerodynamic performance evaluation and optimization in the wind turbine design stage.

The application discloses a water-based parallel projectile interference force analysis method based on cavitation effect, which comprises the following steps: establishing two identical projectile three-dimensional geometric models; introducing the models into a fluid solver to perform mesh division and boundary condition setting. Boundary layer meshes are divided on the projectile surface to capture complex flow phenomena near the wall surface; the models are introduced into a structure solver to perform mesh division and define material properties; monitoring points are set, initial working conditions of the projectiles are given, and numerical solution is performed; and the motion equation of each parallel projectile during water movement is analyzed by using a formula. A cavity interaction model containing the influence of a Weber number is established to obtain coupling forces in the projectile motion equation; a boundary element method is used to quickly reconstruct a flow field, and flow field velocity potential is calculated to obtain the force generated by the cavity combination; and the drag of the projectile is calculated, so that the motion equation of the projectile is solved, and the motion state of the projectile is obtained. The application can analyze the interference force on the projectile.

The application discloses a power transmission line two-three-dimensional linkage arrangement design method, relates to the technical field of power transmission line design, and comprises the following steps: a physical model of a power transmission line is established on a high-precision three-dimensional terrain model by adopting a catenary equation and finite element analysis through adjusted key parameters; the physical model is solved by using a boundary element method; a bilinear interpolation algorithm is used for optimization; and straight two-dimensional and three-dimensional simulation results are generated; and the physical model of the power transmission line is comprehensively evaluated and optimized based on the generated simulation results. The application realizes automatic construction of a high-precision three-dimensional terrain model by combining GIS and machine learning algorithms to automatically identify and integrate features in a multi-dimensional environmental data set, thereby improving the data processing efficiency and significantly improving the accuracy of the terrain model.

This invention proposes a method for simulating the vibration and noise of tires and toothed expansion joints. By establishing a tire-bridge deck finite element model, the tire deformation under load is obtained, and the results are compared and verified using empirical formulas. A tire-bridge deck-expansion joint finite element model is then constructed, setting the relative displacement between the bridge deck and the tire to simulate equivalent tire loading. Multiple analysis steps are set, gradually increasing the translational velocity of the bridge deck and expansion joint to simulate the rolling state of the tire on the bridge deck and expansion joint, calculating the vibration displacement of each node of the tire. The tire vibration displacement is used as a boundary condition and imported into acoustic calculation software. The boundary element method is then used to calculate the time-domain vibration noise of the tire passing over the bridge deck and expansion joint, and the results are compared with measured noise results. This invention can quickly determine the vibration and noise of toothed expansion joints under tire impact, with a difference of less than 10% compared to experimental results. It can be used for noise level prediction in the early stages of expansion joint design, facilitating the optimization of noise reduction expansion joint design.

The invention provides a ball screw pair starting torque calculation method. The ball screw pair starting torque calculation method comprises the following steps: calculating the stress of each ball in a ball screw pair under the action of a load; calculating tangential and normal displacements at any contact point of the ball and the raceway; discretizing a contact area of the ball and the raceway by adopting a boundary element method, and constructing a discrete convolution relation between tangential and normal displacement and shear stress; solving a discrete convolution relationship between the tangential and normal displacement and the shear stress by using fast Fourier transform and a conjugate gradient method to obtain shear stress distribution; according to the friction coefficient and the shear stress distribution, judging a ball adhesion and slip area, and tracking a stick-slip interface evolution process; and when all the balls enter a sliding state, recording the corresponding critical tangential load, and calculating the starting torque of the lead screw through a distributed prediction calculation model. According to the method, on the premise of not depending on a large number of physical tests, the starting torque of the ball screw pair is accurately predicted, and the method is suitable for rapid evaluation of the starting torque under multiple working conditions and multiple parameters.

The invention discloses a physical informed enhanced marine equipment hydrodynamic performance efficient forecasting method and system, and relates to the technical field of ship engineering, and the method comprises the steps: simulating and generating still water resistance data of a ship type sample based on a CFD method, comparing the still water resistance data with an experimental value, and verifying the reliability of the data; the original ship type parameters are converted into dimensionless derivative features, and an original sample set is generated; identifying a parameter blank interval of the original sample set through clustering analysis, generating a supplementary sample based on a potential flow theory boundary element method, and obtaining an extended data set in combination with the original sample set; a density adaptive regularization mechanism and a deviation penalty term are embedded in an XGBoost framework, an EPK-XGBoost model is constructed, an extended data set is used for model training and performance evaluation, and a still water resistance coefficient is predicted through a prediction model with optimal performance. According to the method, the prediction precision of the hydrostatic resistance coefficient can be improved, and the generalization bottleneck of a traditional model in a small sample scene is broken through.

The application discloses a method, device, equipment, medium and product for constructing a ground surface displacement field, and the method comprises the following steps: acquiring first measured ground time history data at a first position during an earthquake; constructing a first measured ground feature vector based on the first measured ground time history data; performing source feature prediction based on the first measured ground feature vector through a pre-trained first source prediction model to obtain a first predicted source feature vector; constructing first predicted source time history data based on the first predicted source feature vector; and calculating predicted ground time history data at any position in a target region through a time-domain boundary element method based on the first predicted source time history data to obtain a ground surface displacement field of the target region, wherein the first position is located in the target region. In this way, the ground surface displacement field of the target region can be quickly and accurately reconstructed after an earthquake, and the timeliness and accuracy requirements of post-earthquake emergency rescue can be met.

The application provides a three-dimensional hydroelastic response calculation method based on a boundary element-explicit finite element coupling, and belongs to the technical field of hydroelastic response calculation based on computer data processing. The application solves wave evolution of a fluid domain by using a boundary element method, and solves dynamic response of an elastic plate by using an explicit finite element method. Inspired by an implicit boundary condition method of wave-rigid body coupling, the explicit dynamic control equation of the structure domain elastic plate is substituted into a boundary condition satisfied by a surface acceleration potential of the fluid domain elastic plate, an additional connection between a time derivative of a surface fluid velocity potential of the elastic plate and a normal derivative thereof is established, and an implicit boundary condition satisfied by the surface of the elastic plate is established. The derived implicit boundary condition is combined with a satisfied Laplace equation, and numerical values of the surface of the elastic plate can be accurately obtained. The three-dimensional time domain numerical method of wave-elastic plate coupling provided by the application can realize stable and accurate calculation of wave load and structure response.

The invention belongs to the field of corrosion science and engineering, and provides a galvanic corrosion simulation solving method, system and device and a storage medium, the method comprises the following steps: constructing a boundary response model and a material domain flux conservation model, the material domain flux conservation model being constructed by introducing a galvanic corrosion reaction current; generating a boundary and material domain interface based on the boundary response model and the material domain flux conservation model; and generating a galvanic corrosion result by applying continuity condition coupling on the interface and iteratively converging the boundary response model and the material domain flux conservation model. A boundary element method is adopted to establish a boundary response model of a corrosive medium, a finite volume method is used for establishing an engine material domain flux conservation model, the boundary response model and the finite volume method are coupled on an interface, and the boundary processing efficiency and the volume solving precision are both achieved. And the current conservation of the motivation material domain is more strictly ensured.

The invention discloses a full-rotation-speed noise prediction method for an outer rotor permanent magnet synchronous motor, and relates to the technical field of motor noise prediction. According to the method, through the full-chain coupling design of air gap magnetic flux density correction, electromagnetic force calculation, rotor vibration modeling, motion sound source parameter extraction, dynamic acoustic modeling with Doppler effect, signal verification and full-rotation-speed efficient optimization, the problems that a traditional model is insufficient in multi-physics field coupling and low in full-rotation-speed calculation efficiency are solved. The core of the method is to establish a correlation between magnetic flux density and electromagnetic force through Maxwell stress tensor, obtain rotor vibration displacement based on an oscillatory differential equation, combine a dynamic Green function correction boundary element method (BEM) to adapt to the Doppler effect of a motion sound source, and verify the accuracy of the model through UCMA + TVSFR signal processing. And finally, accurate and efficient prediction of the motor noise under the full-rotation-speed working condition is realized. The motor noise prediction precision is improved, the application range of the motor noise prediction is widened, and reliable theoretical support is provided for motor noise reduction design.

The application provides a wave field calculation method and system coupling finite elements and artificial boundaries, and relates to the technical field of underground structure anti-seismic technology. In view of the problems that false reflection is prone to be generated in the artificial boundary of the finite element, the calculation efficiency of the boundary element method is low, the material nonlinearity is difficult to handle, and coupling is difficult, the application divides a calculation domain into an external infinite domain and an internal finite domain, solves the external infinite domain by using a fast multipole boundary element method, obtains artificial boundary wave field data, converts the wave field data into equivalent node forces on boundary nodes of the internal finite domain by using an artificial boundary substructure method, and performs non-linear dynamic response analysis on the internal finite domain subjected to the equivalent node forces by using the finite element method, so that the defects of low calculation efficiency and difficult nonlinearity handling are overcome, the ability of the finite element method in handling complex nonlinearity is retained, the unification of high precision and high calculation efficiency is realized, and the stability and reliability of seismic dynamic response analysis are improved.