96 results about "Damping matrix" patented technology

The invention relates to the field of geographic information technology and natural resource management, and discloses an automatic analysis system for land utilization flow change in land change investigation. The system comprises an object-level spatiotemporal spectrum tree reconstruction and data initialization module, a topological potential energy field construction module based on evolution entropy, a multi-scale geometric difference extraction and morphological analysis module, a variable stiffness topological adsorption and decoupling module based on a stiffness ratio, and a flow damping filtering and event serialization module driven by semantic rules. The system constructs a topological potential energy field by using a historical state vector and semantic stiffness, performs one-way adsorption, adjustment or retention on a difference polygon according to relative stiffness, and cleans invalid traffic based on a damping matrix. According to the method, through physical field simulation and semantic logic verification, high-frequency disturbance misjudgment is effectively eliminated, pattern spot boundary correction is ensured to conform to the legal weight, and the authenticity and logic self-consistency of change survey data are improved.

According to the method, a brand-new Naggar-Iwan interface model is established between a pile body and a deformed soil body, so that the synergistic effect between a soil disaster body and a pile disaster-bearing body is simulated. Based on a pile-soil co-working principle and an elastic theory, an elastic-plastic model is adopted to represent and establish a relationship between pile-soil interface frictional resistance and relative displacement, a pile is divided into a plurality of micro-segment units according to a transfer principle, a micro-element is taken for stress analysis, and soil displacement outside the pile-soil interface is calculated by combining boundary conditions and adopting a shear displacement method; according to the generalized Hooke's law strength theory, stress analysis is carried out on each mass point, a generalized structural force-displacement transfer function is constructed by utilizing the basic principle of dynamics, then a complex matrix operation principle in a complex variable function domain is utilized to carry out simplified calculation on a stiffness matrix [K] and a damping matrix [C], and horizontal and vertical displacements of a Naggar-Iwan interface model are obtained; and finally, according to the pile-soil displacement continuous boundary condition, the pile is completely attached to the soil body, and the displacement of the pile can be solved through superposition of the displacement of the soil body and the displacement of the interface Naggar-Iwan model.

The invention discloses a structural dynamic response obtaining method for a fixed offshore wind turbine. The method comprises the following steps: establishing an initial finite element model according to related model data of a fixed offshore wind turbine to be tested, correcting the initial finite element model in combination with obtained actually measured modal parameters, and solving a vibration mode function based on the corrected finite element model; solving kinetic energy and potential energy of the to-be-tested wind driven generator structure; and according to the obtained structural kinetic energy and potential energy, a mass matrix, a stiffness matrix and a damping matrix are constructed based on an Euler-Lagrange equation and a basic kinetic equation, so that a dimensionality-reduced structural kinetic model of the offshore wind turbine is established, an inherent frequency value is obtained through solving, and the dynamic response is obtained. The method effectively overcomes the defects that a model is established depending on finite element software to solve the dynamic response in the prior art, and has the advantages that the modeling process is simple, the solving time is short, multi-field coupling load application can be met, and the control technology is easy to implement.

To provide a control device for a magnetic bearing that enables mode separation of a natural vibration mode with high precision and can design a stable controller with the degree of the controller made small.SOLUTION: With respect to a model for a rotary body controlled by radial magnetic bearings 1, 2, a status space model is structured by excluding a controller which controls a plant from a mode composition model having parameters of a mass matrix, a rigidity matrix, and an attenuation matrix identified and adjusted by a parameter estimation part, and a mode separation part 61 on the input side of controllers 1, 2 inputs a measurement signal of a displacement sensor from the radial magnetic bearings 1, 2 to perform mode separation with a mode separation coefficient. A mode composition part 62 on the output side of the controllers 1, 2 performs mode composition with a mode composition coefficient, and outputs a drive command signal (current, voltage) to electric magnets of the radial magnetic bearings 1, 2.SELECTED DRAWING: Figure 14

The invention provides a direct comprehensive modeling method for a helicopter tail rotor / tail beam coupled substructure, which comprises the following steps of: constructing a blade model, and dispersing the blade model to obtain a mass matrix, a rigidity matrix, a damping matrix and a generalized force vector expression of a single blade; establishing a structural kinetic equation of the tail beam; and finally, according to the displacement boundary condition of the joint of each paddle and the tail beam, converting the paddle structure dynamic equation, and assembling the rigidity matrix, the damping matrix, the mass matrix and the generalized force vector of each paddle after conversion with the rigidity matrix and the mass matrix of the tail beam respectively to obtain the structure dynamic equation of the tail rotor / tail beam coupling system. And establishing a structural dynamic model of the tail rotor / tail beam coupling system. The method is simple and reliable in modeling process and high in universality, is not limited by the distribution type of the tail rotor, can be applied to the non-uniformly distributed tail rotor, and provides a new thought for coupling analysis of the tail rotor / tail rotor and rotor wing / fuselage of the helicopter, dynamic characteristic solving of the tail rotor and analysis of stability.

The invention belongs to the technical field of aerospace, and particularly relates to a modal-based aircraft structure load reconstruction method. The method comprises the following steps: acquiring modal information of a key position of an aircraft structure through a structure finite element model, wherein the modal information comprises a node displacement modal and a unit stress and strain modal matrix; obtaining a node resultant force mode and a profile resultant force / resultant moment mode matrix according to the finite element grid topological relation; and finally, reconstructing the stress / strain intensity of the key position of the structure and the resultant force / resultant moment of the key section from the generalized displacement of the structure according to the modal matrix. The algorithm does not need to process a structural overall rigidity matrix and a damping matrix, and engineering practical application is facilitated.

The invention provides a drill string vibration reduction method and device.The method comprises the steps that longitudinal vibration data and torsional vibration data of a target drill string when a vibration reduction tool is tripped into multiple positions are obtained, and the longitudinal vibration data comprise hook load, a mass matrix, a stiffness matrix, a structural damping matrix, a drilling fluid damping effect matrix, a speed vector and an acceleration vector; the torsional vibration data comprises a rotational acceleration vector, a rotational speed vector, a rotational inertia matrix, a torsional rigidity matrix, a torsional structure damping matrix and a torsional drilling fluid damping matrix; the vibration intensity of the whole well section is determined by applying the longitudinal vibration model, the torsional vibration model, the longitudinal vibration data and the torsional vibration data; and according to the vibration intensity of the whole well section, the optimal tripping-in position of the vibration reduction tool is selected from all the positions, the vibration reduction tool is tripped into the optimal tripping-in position, and the vibration reduction process of the target drill column is completed. The reliability of the tripping-in position of the vibration reduction tool can be improved, and then the vibration reduction effect of the drill column can be improved.

A method for rapidly solving transient dynamics of a crack-containing bearing structure of a bogie belongs to the technical field of bogie structure dynamic analysis, and comprises the following steps: acquiring a three-dimensional geometric model of the bearing structure, the geometric dimension of a crack and the position coordinate dimension of the crack; dividing the finite element model of the bearing structure, and carrying out grid division processing on the crack surface; selecting a main degree-of-freedom node of the finite element model on the surface of the bearing structure and the crack surface; performing substructure analysis on the finite element model of the bearing structure; obtaining a mass matrix, a damping matrix and a stiffness matrix of the finite element model of the bearing structure after the degree of freedom is reduced; carrying out constraint simulation on a crack surface node by adopting a one-way nonlinear rigidity unit; processing constraint boundary conditions; processing the excitation load; and solving a dynamic second-order differential equation set, and judging whether the crack surface is in contact or not. According to the method, the opening and closing effects of the crack can be considered, the transient dynamic response of the crack-containing bearing structure under the action of the external load is obtained, and the solving precision and efficiency are both considered.

The invention discloses a planetary roller screw dynamic modeling method based on a generalized finite element method, and belongs to the field of dynamic characteristic analysis of planetary roller screws. The method comprises the following steps: carrying out unit division on a planetary roller screw finite element model; constructing a dynamic model of each type of unit; respectively establishing mass matrixes, stiffness matrixes, damping matrixes and load column vectors of the shaft section unit, the lead screw-roller contact side thread meshing unit, the nut-roller contact side thread meshing unit and the roller tooth-inner gear ring gear meshing unit; and assembling a system dynamics model to complete planet roller screw dynamics modeling. According to the method, the dynamic characteristics of the real physical model can be accurately analyzed, and an effective means is provided for analyzing the vibration response of the system.

The invention relates to a mechanical arm self-adaption compliance control method and system based on model reference self-adaption and impedance parameter online identification, and belongs to the field of robots. The method comprises the steps that a mechanical arm task space dynamics model is established; designing a reference model; a recursive least square method is adopted, and an equivalent stiffness matrix and a damping matrix of the interaction environment are identified online; designing a composite adaptive law; the expected rigidity of the reference model is dynamically adjusted according to the environment rigidity obtained through identification; and according to sensor data collected in real time, the mechanical arm task space dynamics model, the robot parameter self-adaption law, the environment rigidity, the environment damping and the environment parameter identification robust item, control force is generated, and the mechanical arm is driven through the control force. According to the method and the system, the environment characteristics can be sensed online, and the compliant behaviors can be adaptively adjusted, so that safe, efficient and high-robustness interaction of the mechanical arm in a complex and unknown environment is realized.

The invention discloses a calculation method and system for dynamic response of a deceleration drive assembly under multi-source excitation, and the method comprises the following steps: building a kinetic equation of a gear transmission system based on an overall stiffness matrix, a mass matrix and a damping matrix of the gear transmission system, and carrying out the calculation to obtain a dynamic flexibility matrix of the gear transmission system; establishing a hub motor deceleration driving assembly shell finite element model, and obtaining a system overall kinetic model based on the assembly shell finite element model and the gear transmission system kinetic equation; calculating the dynamic meshing force of the gear as the mechanical excitation of the system; calculating the radial electromagnetic force of the permanent magnet synchronous motor under the no-load and load working conditions as the electromagnetic excitation of the system; mechanical excitation and electromagnetic excitation are loaded to the gear transmission system, and vibration displacement response, speed response and acceleration response at each node of the system are calculated in combination with the dynamic flexibility matrix. According to the invention, the vibration characteristics of the deceleration driving assembly in the actual operation process can be comprehensively and truly reflected.

The invention relates to the technical field of unit gap vibration testing, in particular to a unit gap vibration testing method based on transient numerical simulation, and the method comprises the steps: building a multi-degree-of-freedom dynamic model through obtaining unit structure parameters and operation parameters, carrying out the global optimization of stiffness matrix and damping matrix parameters through employing a genetic algorithm, and generating a high-precision dynamic model; a thermal fluid coupling module is integrated in the model, a coupling weight factor is dynamically corrected in combination with a particle swarm optimization algorithm, a multi-physical-field unsteady-state coupling vibration response equation is generated, and a Pareto optimal solution set is solved in combination with a multi-objective genetic algorithm to optimize gap parameters. According to the invention, real-time evaluation of the vibration state and closed-loop output of fault early warning signals are realized. According to the invention, the problem of insufficient characterization of unsteady state multi-field coupling characteristics in the prior art is solved, and high-precision technical support is provided for online monitoring of rotating machinery.

The invention discloses an industrial robot tail end vibration response calculation method and system, solves the problem of how to improve industrial robot tail end dynamic response prediction accuracy, and belongs to the field of industrial robot dynamics analysis. According to the method, elements of the industrial robot are regarded as rigid bodies or flexible bodies, all assemblies are integrated into a rigid-flexible coupling dynamic model in combination with a robot kinematic model, step-by-step parameter identification is conducted on the decoupled rigid body dynamic model and structural dynamic model, inertial parameters are identified by considering the influence of nonlinear joint friction, and the method is suitable for industrial robot control. Further identifying a rotational inertia matrix in the robot milling kinetic model; joint elastic parameters are identified by considering the influence of non-linear joint rigidity, and a damping matrix in a robot milling kinetic model is further identified. And the torque fluctuation of each joint is predicted, the vibration response of each joint is calculated in combination with a robot milling kinetic model, and finally the robot tail end vibration response is calculated in combination with robot kinematics.

According to the rotor centering fault dynamic model of the rotary mechanical gear coupling, the motion state and the stress condition of the coupling under the non-centering condition are analyzed, the radial force change caused by different torque transmission in the gear meshing process is obtained, and the non-centering force exciting force expression applied to a rotor system by the gear coupling is obtained; establishing a dynamic vibration equation of the rotor system, solving to obtain an overall unit stiffness matrix, a mass matrix and a damping matrix of the shaft system, and deducing a motion differential equation of the rotor system; the method comprises the following steps of: obtaining a displacement value, a speed value and an acceleration value of each node at each moment, drawing an axis trajectory diagram, a time domain oscillogram, a spectrogram and a poincare sectional view to analyze the dynamic behavior of a coupling on a transit subsystem and the action of the coupling on the motion characteristics of the coupling by parameters of a non-centering quantity, rotating speed and torque system, and analyzing the stability of the system under different rotating speeds to obtain the stability of the system. And great help can be provided for preventing, analyzing and processing the centering fault of the coupler rotor.

The invention relates to the technical field of wind turbine generator simulation, and particularly provides a wind turbine generator complete machine simulation method and device, and the method comprises the steps: integrating a characteristic matrix of each unit in a finite element model of a wind turbine generator into a complete machine motion balance equation of the wind turbine generator based on the node number of each unit in the finite element model of the wind turbine generator; converting the complete machine motion balance equation of the wind turbine generator to obtain a complete machine motion balance equation without constraints; integral solving is conducted on the complete machine motion balance equation with the constraint eliminated, and a complete machine simulation result of the wind turbine generator is obtained; wherein the characteristic matrix comprises a mass matrix, a damping matrix and a stiffness matrix, and the simulation result comprises node velocity vectors of all units in a finite element model of the wind turbine generator. The technical scheme provided by the invention can be used for guiding the whole unit, simulation design and tool development, and has a wide application prospect.

The invention discloses a vibration detection method for constructing an edge calculation model based on Simulink physical modeling, and the method comprises the steps: constructing a multi-degree-of-freedom vibration model through Simulink, dynamically adjusting the quality, rigidity, a damping matrix, temperature and load parameters, simulating the vibration characteristics of a complex working condition, and fusing simulation and actual measurement data to generate a training set; the model is converted into an edge available format and compressed to be within 100 KB, and edge hardware is adapted; carrying out joint training and online updating on edge nodes by utilizing transfer learning and the like; and the vibration signals are classified in real time through a lightweight model. According to the method, the problems of fixed model parameters, insufficient data fusion and poor edge adaptability in the traditional technology are solved, accurate simulation of the vibration characteristics of the industrial equipment, efficient data utilization and low-delay detection of the edge end are realized, the vibration detection precision and real-time performance are improved, and the method is suitable for fault diagnosis and predictive maintenance of the industrial equipment.

The invention discloses a viscoelastic boundary verification method, device and equipment based on isoparametric elements and a medium, and the method comprises the steps: building a three-dimensional geometric model of a target structure according to geometric dimensions and material attributes, discretizing the three-dimensional geometric model into initial three-dimensional subunits, and then building an initial finite element mesh model; after identifying a target boundary surface to be applied with an artificial viscoelastic boundary, assigning boundary parameters to obtain each three-dimensional subunit and form a finite element model; all the three-dimensional subunits are mapped to a standard unit through equal-parameter coordinate transformation, an equivalent stiffness coefficient matrix and an equivalent damping coefficient matrix are obtained through calculation and then stacked and assembled, and an overall stiffness matrix and an overall damping matrix are formed; and calculating displacement response data based on the overall stiffness matrix and the overall damping matrix. According to the embodiment of the invention, by introducing the isoparametric coordinate transformation, the irregular boundary form can be directly processed without introducing an additional boundary unit, and the calculation requirement of an actual complex engineering model is met.

The invention relates to the technical field of data processing, in particular to a structure dynamic stiffness analysis method based on frequency response function polycondensation substructure impedance coupling, which comprises the following steps: acquiring node information, unit connection relation and material attribute based on a global finite element model; defining a focus point set, a boundary point set and an internal point set according to the unit connection relationship; partitioning the global quality matrix, the stiffness matrix and the damping matrix to obtain a partitioned system matrix; introducing an inertia compensation term to construct a transformation matrix based on the block system matrix and the highest analysis frequency of the system, condensing the system matrix until only the freedom degrees of a concern set and a boundary point set are reserved, and calculating a dynamic stiffness matrix in a frequency domain; a dynamic stiffness result of a focus set is extracted through inverse operation of a dynamic stiffness matrix, the calculation scale is remarkably reduced through system matrix condensation, meanwhile, the inertia effect and the stiffness coupling effect of a far-field structure are strictly reserved, and the contradiction between low calculation efficiency of a global model and precision distortion of a local substructure method is effectively solved.

The invention discloses a structure parameter-load input joint identification method based on a Gaussian potential force model, and the method comprises the steps: obtaining a mass matrix, a stiffness matrix and a damping matrix, and constructing a state-space equation; modeling unknown load input into a zero-mean stationary Gaussian process with a specific covariance function to fuse prior information of the covariance function, and converting into an equivalent state-space equation; obtaining sparse dynamic response characteristics, and establishing a state space measurement equation; a structure state and load input are augmented into a state equation, the state equation and a measurement equation set are synthesized into a complete Gaussian process potential force model, unknown structure parameters are regarded as hyper-parameters, kernel function hyper-parameter optimization and structure parameter identification are achieved with the criterion of a maximized negative likelihood function, sequence reasoning is conducted on the Gaussian process potential force model, and the Gaussian process potential force model is obtained. Estimation of load input is obtained. The method has the advantages of being stable in parameter recognition result, high in precision, stable and reliable in load estimation, higher in robustness to model errors and measurement noise and the like.

The invention discloses a vehicle time history response calculation method and device, electronic equipment and a storage medium. The method comprises the following steps: acquiring a mass matrix, a damping matrix and a stiffness matrix of a to-be-tested vehicle; inputting the mass matrix, the damping matrix and the stiffness matrix into a pre-constructed time history response calculation model; according to the mass matrix, the damping matrix and the stiffness matrix, the time history response of the to-be-tested vehicle is calculated through a time history response calculation model; wherein the time history response comprises a displacement vector, a speed vector and an acceleration vector. According to the embodiment of the invention, the calculation efficiency can be remarkably improved while the calculation precision is ensured, and the method is suitable for time-history response analysis of the key structure of the commercial vehicle under the complex dynamic load.

The present application relates to the field of power system control and power electronic energy storage technology, in particular to a generator set transient power compensation system and method thereof, the method comprising: collecting stator voltage, stator current, rotor angular velocity, power angle and DC bus voltage, and mapping into a generalized state vector; constructing a port-controlled Hamilton system model containing an initial interconnection matrix and an initial damping matrix based on preset physical parameters and obtaining a Hamilton energy function; taking partial derivative of the Hamilton energy function with respect to the generalized state vector, calculating an energy gradient vector, dynamically reconstructing a virtual interconnection matrix and a virtual damping matrix, analyzing control input and converting into a duty cycle command to send to an energy storage converter to perform transient power compensation; the system comprises a data acquisition module, a Hamilton energy controller and an energy storage converter; faster transient recovery, lower mechanical stress and more stable closed-loop response can be achieved.

The invention provides a workshop floor response spectrum calculation method adopting substructure analysis, and the method comprises the steps: solving a site response problem of a free field through a semi-analytical method based on the modulus and damping of the free field, and obtaining transmission boundary information; respectively calculating foundation impedance matrixes of transmission boundary information through a flexible volume method; calculating an upper structure matrix according to the foundation impedance matrix; the upper structure matrix comprises an upper stiffness matrix, an upper mass matrix and an upper damping matrix; constructing a motion equation according to the foundation impedance matrix and the upper structure matrix, and solving to obtain a frequency domain displacement response transfer function; and performing interpolation calculation on the frequency domain displacement response transfer function to obtain seismic response. According to the method, the calculation of the reaction spectrum is realized through a substructure analysis method for decomposing a linear soil-junction interaction analysis problem into a series of relatively simple subproblems, the calculation efficiency is improved, and the model construction period is shortened.

The invention belongs to the field of mechanical simulation analysis of composite material structural parts, and particularly discloses an equivalent mechanical modeling method of a variable-thickness composite material component, which comprises the following steps: acquiring a laying deformation measure, and determining deformation distribution of fiber cloth by using the laying deformation measure through a fishing net method; mapping the deformation distribution of the fiber cloth to a target structure grid by using a grid mapping method; constructing a numerical model of equivalent mechanical characteristics of the target structure grid by using a multilayer structure equivalent calculation formula; the equivalent mechanical characteristics comprise equivalent density, an equivalent stiffness matrix and an equivalent damping matrix; and determining a numerical value implementation program of the numerical value model, and performing equivalent mechanical analysis simulation on the variable-thickness composite material component by the numerical value model through the numerical value implementation program by adopting a finite element method. According to the method, the modeling accuracy of the variable-thickness composite material component is improved.

The application discloses a stiffness and damping optimization method, system, device, medium and product of a vehicle suspension based on a back propagation neural network, and relates to the technical field of vehicles. The method comprises the following steps: training a back propagation neural network based on a training set to obtain a trained back propagation neural network; extracting the trained back propagation neural network by adopting a Taylor expansion method and a finite difference method to obtain a matrix; constructing a nonlinear multivariate inter-axle stiffness-damping objective function based on the matrix; obtaining an input variable sequence and an output variable sequence of a vehicle; and optimizing the stiffness and damping of the vehicle suspension under a constraint condition by taking the function value of the nonlinear multivariate inter-axle stiffness-damping objective function as the target, so as to obtain an optimal stiffness-damping matrix and complete the stiffness and damping optimization of the vehicle suspension. The application can improve the driving smoothness and steering stability of the vehicle.

The invention discloses an air bearing surface waviness optimization method and system in an air bearing-rotor system, and the optimization method comprises the steps: calculating the rigidity and damping coefficient of an air bearing with waviness and the rigidity and damping matrix of a rotor based on the structure parameters and material attributes of the air bearing-rotor system and the waviness parameters of the bearing; timoshenko beam unit modeling is conducted on the air static pressure rotor, the air static pressure rotor is divided into a plurality of units, and the mass matrix, the rigidity matrix and the damping matrix of each unit are solved; coupling the rigidity and the damping coefficient of the air bearing with the waviness with the rigidity and the damping matrix of the rotor at corresponding nodes to obtain an air bearing-rotor model with the waviness; performing time-varying dynamic response solution on the air bearing-rotor model with waviness to obtain a bearing-rotor system dynamic response result corresponding to the bearing surface waviness parameter; according to the method, the influence of the surface topography parameters in the air bearing structure on the system dynamics response can be considered.

The invention relates to the technical field of wind driven generators, in particular to a wind turbine tower-wind wheel interaction modeling method based on an aerodynamic damping matrix, which comprises the following steps of: linearizing aerodynamic force transmitted to a tower by a wind wheel based on a blade element momentum theory to obtain aerodynamic force and aerodynamic damping force of a rigid tower; wherein the aerodynamic damping force can be obtained by multiplying an aerodynamic damping matrix by a tower top speed, and elements of the aerodynamic damping matrix can be obtained according to an average wind speed, a wind wheel rotating speed and a blade pitch angle in a corresponding environment; in the modeling system, the aerodynamic force and aerodynamic damping matrix of the rigid tower is applied to a top node of the finite element model of the tower, and modeling is completed. The method overcomes the defects that in the prior art, a complete model of the wind turbine needs to be established in corresponding modeling software for simulating the dynamic response of the wind turbine, aerodynamic force and movement of all parts of the wind turbine need to be coupled in each time step, the calculated amount is large, and the simulation operation time is long.

To predict flutter and buffeton set in a body (2) moving in a flow (3), structural properties of the body (2) are described in a structural model (13) comprising a mass matrix (M), a stiffness matrix (K), and a damping matrix (B), and from which at least one structural eigenmode of the body (2) is determined under the assumption that no aerodynamic forces act on the body (2). Aerodynamic properties of the body (2) in the flow (3) are described in an aerodynamic model (14) under the initial assumptions that the body (2) performs movements (15) according to the at least one structural eigenmode and that the flow (3) has no influence on the movements of the body (2). At least one dominant flow eigenmode of the flow (3) and aerodynamic forces acting on the body (2) are determined from the aerodynamic model (14) under the initial assumptions.The aerodynamic model (14) is then converted into an aeroelastic model (12) by coupling it with the structural model (13), whereby during a first sweep (22) while keeping the dynamic pressure (q. dyn ) the mass matrix (M) is first scaled with a large scaling factor (q m ), which is then successively reduced to 1, and the at least one dominant flow eigenmode is tracked with regard to its eigenvalue (16). Subsequently, the dynamic pressure (q dyn ) is gradually increased, while the scaling factor (q m ) remains equal to 1, wherein the at least one structural eigenmode and the at least one dominant flow eigenmode are tracked with regard to their eigenvalues ​​(16, 18, 20).

The present invention relates to a method for converting the vibration response of a cabin structure from onshore to underwater, comprising: S1, testing the structural mode under onshore support state, performing modal analysis to obtain the mass, damping and stiffness matrix M+M 支 、C+C 支 , K; S2, when the equipment in the onshore structure is running, test the structural vibration response and obtain the vibration displacement response u1 of the cabin structure onshore; S3, calculate the constant excitation vector F0 inside the structure; S4, additional displacement impedance Z for the bottom support 支 , additional displacement impedance Z of adjacent structures 邻 , additional displacement impedance of water Z 水 Calculate the following: S5. Calculate the inherent mass matrix M and damping matrix C of the compartment structure in the free state; S6. Calculate the underwater vibration displacement response u2 of the compartment structure when the same equipment within the compartment is operating. The present invention modifies the onshore compartment boundary conditions based on additional impedance, eliminating the differences in bottom support, structural truncation, and water environment between the onshore and underwater compartments, thereby enabling the estimation of underwater vibration of the onshore compartment.

The invention discloses a low-damping type matrix overflow-discharging vacuum gypsum mold forming mold and a casting method, the low-damping type matrix overflow-discharging vacuum gypsum mold forming mold comprises a mold body and overflow-discharging capillary tubes, and the overflow-discharging capillary tubes are inserted into the mold body in a sliding mode; the multiple overflow discharging capillary tubes are arranged in an array mode. According to the low-damping type matrix overflow discharging vacuum gypsum mold forming mold and the casting method, the overflow discharging capillary tubes are arranged, so that the overflow discharging capillary tubes and the gypsum mold are combined into a whole in the gypsum mold forming process, the demolding resistance of the gypsum mold is reduced, and the gypsum mold is complete and not prone to being damaged; and in the gypsum mold dewaxing roasting process, the phenomena of overflow hole blockage and crack do not occur, so that the final finished product quality is improved.

The invention provides a method and system for predicting the elastic stability of an aircraft under the action of swing nozzle thrust, and the method comprises the steps: S1, constructing a one-dimensional finite element model, and obtaining an inertial measurement assembly position vector L and a swing nozzle thrust action point position vector R; s2, checking the one-dimensional finite element model to obtain a generalized mass matrix, a generalized stiffness matrix, a generalized damping matrix and a modal shape matrix; s3, establishing a state space model of a transfer function from the projectile body angular velocity to the swing nozzle swing angle response and the swing angle acceleration response, and obtaining a state equation; s4, establishing a generalized structure kinetic equation under the action of the thrust of the swing nozzle; s5, the generalized structure kinetic equation and the state equation are combined; and S6, evaluating the elastic stability of the aircraft. According to the method, stylized prediction of the elastic stability of the aircraft under the action of servo control and swing nozzle thrust can be realized, and the method has good rapidness and applicability.