39 results about "Modal synthesis" patented technology

The invention discloses a vibration modeling and analyzing method of a crack impeller structure of a centrifugal compressor. The vibration modeling and analyzing method comprises the steps of firstly, providing a modeling method of a centrifugal impeller, obtaining a whole model by rotating and converting a finite element model of a section of the impeller, reducing the DOF (Degree of Freedom) of a system by adopting a hybrid interface modal synthesis method, and simulating a breath effect of a crack by defining a contact mode on a crack interface; secondly, providing a method for solving large-scale symmetrical sparse matrix-inverse matrix, and thus obviously reducing the memory space needed by calculation; finally, providing a method for carrying out statistical analysis on resonant frequency of the crack impeller structure, considering dissonant factors such as manufacturing error and state degradation which exist in an actual impeller, and obtaining statistical regularity of structure resonant frequency under a random dissonant mode. According to the vibration modeling and analyzing method disclosed by the invention, the calculating accuracy is ensured, obvious improvement effect of calculating efficiency is realized at the same time, and a high-efficiency analyzing method is provided for optimal design of the impeller and quantitative diagnosis of the crack.

The invention relates to a modal synthesis dynamic modeling and analysis method for an automobile driving axle system. The method is characterized by comprising the steps that 1, a finite element model of all components of a driving axle is established, boundary nodes are defined according to the connecting relation between the components, a modal synthesis model of all the components is established, and a modal synthesis rigidity matrix and a mass matrix of all the components are obtained; 2, a connecting relation model of all the components is established; 3, the modal synthesis rigidity matrix and the mass matrix of all the components are assembled according to the connecting relation, a complete modal synthesis dynamic model of the driving axle system is established, and a rigidity matrix and a mass matrix of the driving axle system are obtained; 4, natural vibration frequency and a regular vibration mode of the dynamic model of the driving axle system are calculated, and a mode superposition method is adopted to calculate the dynamic response of the driving axle system under excitation of dynamic engaging force of gears of a main reducing gear. In the whole modeling process, high universality and calculating efficiency are achieved, and the method can be widely applied to dynamic analysis of a gear transmission system.

The invention discloses a synthetic modeling method of rotor and airframe coupling dynamics modality, and belongs to the dynamic design technology of helicopters. The synthetic modeling method of the rotor and airframe coupling dynamics modality is suitable for the dynamic stability and dynamic response analysis modeling of single-rotor and multi-rotor coupling. The synthetic modeling method analyzes the air resonance instability of a rotor blade by aiming at the rotor blade operation pneumatic environment of a flight state stipulated by a flight envelope rule which needs to considers to cover and properly exceed the performance requirements of the helicopter, researches the influence of high-speed high-overload flight state parameters, looks for the structural design parameters of rotors, blades and a steering control system which cause or affect the generation of the air resonance, and determines the instability boundary of the air resonance. Through the sensitivity analysis of the air resonance by the structural design parameters, a structural design parameter range which affects the air resonance is determined, and a design measure for expanding the security boundary of the air resonance is put forward.

The invention discloses an optimization method for controlling vibration of a combined cycle unit by adjusting the bearing elevation. The method comprises the steps that 1, substructure partitioning is conducted; 2, coefficients after the bearing elevation changes are solved; 3, a motion equation at any revolving speed is determined and established according to a fast system matrix algorithm; 4, degree-of-freedom reduction is conducted according to a fixed interface modal synthesis method; 5, system synthesis is conducted, and a motion equation after reduction is established; 6, steady-state response solution is conducted on a reduction system; 7, an optimization model is built; and 8, an optimization model is solved by adopting a genetic algorithm. According to the optimization method, the fast system matrix algorithm at any revolving speed is developed, bearing parameters are calculated by adopting a difference model, degree-of-freedom reduction is conducted according to the modal synthesis method, the requirement on computer resources is reduced, the solution speed is increased, and the optimization model is solved by adopting the genetic algorithm finally. The optimization method has the advantages of being high in calculation speed, saving calculation resources and the like.

The invention discloses a constant geometric method-based composite thin-walled structure inherent frequency design method. The method comprises the following steps of: describing a curved surface shape of each sub-structure of an initial thin-walled composite structure through NURBS, and classifying sub-curved surfaces into a design domain and a non-design domain, changing the shape of the designdomain through movements of control points, and setting positions of the control points as design variables; carrying out grid partition on the structure by adoption of a constant geometric Kirchhoffshell unit, calculating quality and rigidity matrixes of the sub-structures, and carrying out modal analysis; respectively constructing reduction models of the sub-structures by utilizing the first several orders of feature values and feature vectors, forming a reduction model of the composite structure through an immobile interface modal synthesis method, and solving the reduction model to obtain a fixed frequency; and carrying out design sensitivity analysis on the structure to obtain an analysis sensitivity, for a shape design variable, of the fixed frequency, and finally solving a designproblem through a gradient-based optimization algorithm. According to the method, the grid generation process is simplified and the optimization efficiency is improved at the same time.

The invention relates to a secondary polycondensation method of a finite element model of a spacecraft. Finite element physical models of a main structure and all secondary structures of the aircraftare built respectively, then the finite element physical models of part of the secondary structures are subjected to primary polycondensation through a mixed interface mode synthesis method, and the finite element physical models or a primary polycondensation model of the secondary structures and the finite element physical model of the main structure of the aircraft are assembled to obtain a mixed model; finally, the mixed model is subjected to secondary polycondensation to an aircraft-rocket master node of the aircraft and a carrier rocket through a fixed interface mode synthesis method, a rigidity and quality matrix obtained after secondary polycondensation and a transfer matrix corresponding to an internal response point are acquired, and results are output to be used for coupling loadanalysis of the spacecraft and the rocket. The method solves the problem that an existing primary polycondensation method cannot handle secondary polycondensation, calculation and evaluation of polycondensation errors are added, and the calculation efficiency and accuracy are improved.

The invention discloses a novel measurement method for the dynamic characteristic of a tool nose of a micro-diameter milling tool, which belongs to the field of micromachining. The novel measurement method is characterized by comprising the following steps of clamping the micro-diameter milling tool in a tool chuck of a main shaft, adopting a miniature pulse hammer to carry out shock excitation on the micro-diameter milling tool at a position point where a cutter handle is arranged, adopting a scanning laser doppler vibrometer to measure vibration displacement of a measuring point set on the milling tool, carrying out modal synthesis on vibration response through signal collecting and processing software, and acquiring the dynamic characteristic of the tool nose of the micro-diameter milling tool. According to the novel measurement method, the pulse excitation of the hammer is not applied on the tool nose position of the micro-diameter milling tool, so that the damage of the tool nose is avoided; the non-contact measurement is adopted, so that the method is applicable to the milling tool with smaller diameter, and on-line measurement can be realized. Compared with the traditional measurement method, the method adopts a pure experimental method to acquire the dynamic characteristic of the tool nose, so that higher measurement accuracy can be achieved, and meanwhile, the measurement method is simple in device and convenient to implement.

The invention discloses a quasi-flexible body discrete suspension modeling method based on a bushing, which relates to the technical field of automobile suspension. By establishing a rigid body component model of the suspension, the model needing to be flexible is divided into several rigid blocks with centralized mass. The rigid blocks are connected by bushings, and the model stiffness to be flexible is approximately replaced by bushing stiffness, which is used as the bearing element. Input rigid body model parameters; The suspension dynamics simulation analysis is carried out and the simulation results are output. Compared with the modal synthesis method, the flexible body modeling method has stronger parametric modeling ability and simplicity. Compared with the flexible body discretization method, the simulation accuracy of thin plate parts is higher, and because the degrees of freedom of the bushing do not affect each other, so the shear locking can be effectively avoided when therigid parts are discretized by the flexible body discretization. In addition, by setting the liner stiffness, the expected simulation optimization results are obtained, which plays a guiding role in the optimization design of the model.

The invention discloses an efficient quantitative modeling method for an impeller-bearing-rotor system, and the method comprises the steps: 1, respectively building a rotating shaft kinetic model andan impeller kinetic model through an iron-wood-octane beam finite element model and a three-dimensional entity finite element model, and building a kinetic model of a rolling bearing through a five-degree-of-freedom lumped parameter model; 2, establishing at least two six-degree-of-freedom virtual main nodes on a common connection interface of an impeller and a rotating shaft in the impeller dynamic model; 3, constructing non-matching displacement coordination transformation from the entity node to the virtual main node; and 4, performing order reduction on the impeller model by adopting a fixed interface modal synthesis method, and integrating the impeller model, the rotating shaft model and the bearing model to obtain an order reduction model of the whole impeller-bearing-rotor system. According to the method, the analysis efficiency of the rotor kinetic model can be improved, the order of the model is reduced, and a technical support is provided for modeling, analyzing and solving work of large rotating machinery.

The invention belongs to the technical field of structural vibration reduction dynamics calculation methods, in particular to a cyclic symmetry structure frequency response analysis method of an additional dry friction damper. The cyclic symmetry structure frequency response analysis method of the additional dry friction damper comprises the following specific operation steps: S1, establishing a structural member and damper sector kinetic equation, s2, establishing a sector finite element model; obtaining a sector quality and rigidity matrix; s3, performing degree-of-freedom compression on thesector model by applying a modal synthesis method; s4, adding a complex constraint boundary condition to the compressed model; s5, performing time domain representation of dry friction force; S6, solving a nonlinear equation set by using a mixed time-frequency method. According to the cyclic symmetry structure frequency response analysis method of the additional dry friction damper, storage resources and calculation time are greatly saved, the calculation time saving ratio is equivalent to the saving ratio of the storage resources, the number of nonlinear degrees of freedom participating in iteration is reduced, the convergence risk is effectively reduced, and an efficient and robust frequency response solving algorithm is formed.

The invention discloses a substructure response reconstruction method and system, and a storage medium. The method employs model condensation to generate a super-unit model based on a finite element model, does not need to consider the boundary conditions of all substructures, can better adapt to the dynamic response reconstruction of a large-scale complex engineering structure, and expands a current time domain reconstruction method based on EMD decomposition, the modal synthesis is used in the response reconstruction method for the first time, the response of each main modal in the whole substructure is reconstructed based on the interface response of the known substructure, the response reconstruction only needs to be carried out under the condensed substructure, and then the main modeof a super-unit model is expanded to the response of the degrees of freedom of all internal units in the finite element model through coordinate back calculation, so that the accuracy is ensured, thereconstruction efficiency is greatly improved, the computer memory is saved, and the analysis speed is high.

The invention discloses a helicopter rotor and fuselage coupling stability modeling method, and belongs to the helicopter dynamics modeling and analysis technology. The method includes: adopting a modal synthesis technology to perform comprehensive modeling on a rotor and fuselage dynamics coupling system, describing the motion of a fuselage and rotors in different coordinates, establishing structural dynamics finite element method models of isolated rotor blades and an airframe structure respectively, adopting an aerodynamic model to model aerodynamic force, and deducing a rotor/airframe coupling system kinetic equation by applying the Hamilton principle; establishing an automatic flight control system control model, and deriving an aerodynamic load matrix related to the pitch variable, thereby establishing a rotor wing and aircraft body coupling aeroelastic stability analysis model considering the flight control system; and finally, solving a characteristic value through a characteristic value method, and judging the stability of the coupling system through a characteristic value solution. The model can be used for calculating and analyzing the'ground resonance 'and'air resonance' stability of all advanced helicopters, and key technical support is provided for model design and development.

The invention discloses a box-type thin-walled part milling stability prediction method, used for solving the technical problem of lower prediction accuracy of an existing thin-walled part milling stability prediction method. The technical scheme is that the method comprises the steps of firstly using a modal hammer experiment to test a modal parameter of a tool and a modal damping ratio of a workpiece; then using a substructure modal synthesis method to calculate a workpiece dynamic characteristic with considering a material removal effect; afterwards, extracting dynamic displacements of the workpiece at different tool positions and different axial heights; finally establishing a multi-point contact milling dynamical model, substituting the previously obtained workpiece dynamic characteristic into the model, and solving reliability. Changes due to material removal, changes at different tool positions, and changes along the axial direction of the tool of the workpiece dynamic characteristic are considered at the same time, thus improving the prediction accuracy of box-type thin-walled part milling stability.

A three-dimensional entity unit modeling method of a gear system comprises the steps that firstly, according to the structural characteristics of the gear transmission system, HYPERMESH software is used for preprocessing a complex structure, three-dimensional entity unit models of a gear substructure and a transmission shaft substructure are established respectively, and accurate division and optimization of grids are carried out; then, ANSYS software is used for carrying out modal analysis and extracting a mass matrix and a rigidity matrix; then, nonlinear factors such as time-varying rigidity are considered, and gear tooth meshing of the gear transmission system is modeled through the Pasternak elastic foundation beam theory; finally, according to the interface displacement coordinationcondition, integrating, coupling and dimensionality reduction are conducted on the models of the transmission shaft, the gear and the bearing system through a modal synthesis method, and a high-precision gear transmission system dynamic model matched with the dynamic characteristics of the equipment is established. According to the method, the model precision can be guaranteed, and the calculationefficiency can be remarkably improved, so that a more efficient and accurate method is provided for quantitative analysis of the vibration of the gear transmission system.

The invention discloses a dynamic response reconstruction method and system based on EMD and model polycondensation and a computer readable storage medium. According to the method, substructure division is carried out on a finite element model, then degree-of-freedom division is carried out on each substructure, modal coordinate transformation is carried out, each substructure is coupled into a super-unit model, a modal shape matrix of the unit model is solved, and modal response is extracted from measurement data through an EMD decomposition method, and finally a substructure interface response is reconstructed based on the extracted response data and the modal shape matrix. According to the method, the super-element model of the structure is generated based on the finite element model, the current time domain reconstruction method based on EMD decomposition is expanded, the modal synthesis method is used in the response reconstruction method for the first time, response information of key points is predicted through a modal superposition method, the dimensionality of a finite element model related parameter mathematical matrix is effectively reduced, the calculation efficiency ofresponse reconstruction is improved, and the method has the advantages of high accuracy, high analysis speed and the like.

The invention discloses an NVH analysis method based on a super-element and finite element hybrid model. The method comprises: establishing a whole vehicle finite element model, condensing part of finite element sub-module models in the finished automobile finite element model into independent super-unit sub-module models through a modal synthesis method, establishing a whole vehicle hybrid modelcomposed of a super-unit sub-module model and a finite element sub-module model, and performing NVH simulation analysis by using the vehicle hybrid model. According to the method, the repeated calculation times and time of the finite element submodule are reduced without changing in analysis, and the more the repeated calculation times are, the more obvious the advantage of saving time is, so thatthe calculation speed is obviously increased; and meanwhile, the storage space occupied by the process file and the calculation result is greatly reduced.

The invention provides a semi-supervised multi-mode nuclear magnetic resonance image synthesis method based on coarse-to-fine learning. The method comprises the following steps: constructing most of unpaired data and a small part of paired data by using a multi-modal data set of all cases, constructing an MRI synthesis model comprising a generative network and an enhanced network, training the generative network by using all the data, training the enhanced network by using the small part of paired data, and constructing an MRI synthesis model comprising the generative network and the enhanced network; inputting an image of a source mode into the trained generation network, mapping the image of the source mode into a coarse synthesis image of a corresponding target mode by using the learned cross-mode distribution mapping relation, inputting the coarse synthesis image into the trained enhancement network, and performing refined enhancement on the coarse synthesis image of the target mode by the enhancement network to obtain a refined enhancement image of the target mode; and obtaining a cross-modal synthesis MR image of the target modal. The method can be applied to cross-modal medical image synthesis, the existing source modal image of the patient is used for synthesizing the target modal image, and assistance is provided for assisting doctors in disease diagnosis.

The invention discloses a modeling analysis method for a complex cable network system, which adopts a substructure modal synthesis method and a model order reduction method to form a function of analyzing the dynamic characteristics and dynamic response of the cable network system. Each main cable in the cable net structure is considered as a sub-structure, and the model of the overall structure is established by coupling the deformation continuity and stress balance of each sub-structure at the damper/connecting piece connecting position and the mechanical characteristics of the damper/connecting piece. The established model can be used for analyzing the response of an actual cable net under the action of an external load, and can be used for complex eigenvalue analysis to obtain the frequency, damping and vibration mode of the system; the established model is a dimensionless model and can be used for researching general characteristics of a cable net structure and designing parameters of dampers and inter-cable connecting pieces so as to optimize the vibration control effect of a cable net system.

The invention discloses an automobile damping patch position optimization method and system, and the method comprises the steps: building a finite element model of a white automobile body, carrying out the targeted damping optimization and sensitivity analysis of a risk frequency through the combined use of an effective sound power analysis method and a modal synthesis method, carrying out the sensitivity analysis of a confirmed damping fin, finding a position with high sensitivity according to a sensitivity analysis result to carry out damping fin preliminary arrangement design, finally performing Trimbody noise transfer function analysis on a potential damping fin, and after the damping fin is added, providing an obvious scheme for optimizing the right ear response of a driver. Accordingto the method, the development time can be shortened, the research and development cost can be reduced, the noise and vibration performance of the whole vehicle can be improved, the sensitivity of scientifically and accurately recognizing the damping fin is high, and the peak value with potential design risks is enhanced in a targeted mode.

The invention discloses a nonlinear kinetic analysis method for an ultrahigh voltage transmission line under the action of wind vibration excitation. The method comprises the steps that firstly, the wind velocity time series is simulated by applying an AR model in a linear filtering method; secondly, wind velocity time series curves of simulating points are verified with a spectral function, and the conclusion that a numerically simulated fluctuating wind velocity is basically matched with an actual wind velocity is obtained; thirdly, a kinetic equation of a transmission line system is solved through a direct numerical integration method and a nonlinear modal theory, the wind velocity time series curves of part of the simulating points are obtained, the time series curves solved by the two methods are compared through a power spectrum, the fact that the power spectrum of the time series curves obtained through modal superposition and synthesis is better matched with the power spectrum which is directly solved can be obtained, and the result indicates that the transmission line dynamic response time series curve solved through modal synthesis is reliable. According to the nonlinear kinetic analysis method for the ultrahigh voltage transmission line under the action of wind vibration excitation, the characteristics of fluctuating wind are determined through the two modes, the characteristics of the fluctuating wind can be determined, and a theory and reference basis is supplied to static and dynamic engineering design of the ultrahigh voltage transmission line.