125 results about "Mass matrix" patented technology

The invention provides a statistical energy analysis parameter acquisition method based on a finite element method and a power input method. A finite element model of a structure is established according to a geometric model of the structure, boundary conditions are applied, the finite element model of the structure is subjected to mode analysis, a mode of a system and a rigidity matrix and a mass matrix of a subsystem are obtained, vibration energy of the subsystem and input power of the system are obtained through a power flow model, and statistical energy analysis parameters are obtained through calculation through the power input method. The finite element method and the power input method are combined to obtain the statistical energy analysis parameters of the structure, the calculated rigidity matrix, mass matrix, mode shape and inherent frequency are obtained through the finite element method, the input power and the vibration energy are obtained through calculation through the power flow model, and the input power and the vibration energy are substituted into the power input method for calculation to obtain the statistical energy analysis parameters. According to the method, statistical energy analysis can be carried out aiming at the problem of strong coupling between structures, the limitation about weak coupling assumption between the structures in existing statistical energy analysis is solved, and the method can be popularized to complex structures.

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 relates to the technical field of deep sea operation type ROVs, in particular to a dynamics and kinematics estimation method for a deep sea operation type ROV. The method comprises the steps of establishing a fixed coordinate system, a body coordinate system and a propeller coordinate system, and estimating a matrix for coordinate transform in six freedom degrees; estimating the mass matrix of the operation type ROV and a caused coriolis force and centripetal force matrix; estimating water power borne by the operation type ROV; estimating the static force borne by the operation type ROV; estimating the thrust of the operation type ROV; estimating unknown disturbance terms; determining the ultimate dynamic and kinematic model of the operation type ROV. According to the dynamics and kinematics estimation method for the deep sea operation type ROV, dynamic and kinematic modeling of the deep sea operation type ROV is carried out on the basis of dynamics, fluid mechanics, submarine maneuverability and other theories, aiming at complex mathematic models of underwater vehicles, the symmetry theory and the method of neglecting small magnitudes are utilized to simplify the mathematic models of the deep sea operation type ROV, and the established models can be used for estimating the stress situations of the ROV more accurately.

The invention relates to a meshless cloth-based simulation method. The method comprises the following steps of: (a) parameterizing a given cloth model omega onto a middle surface lambda and determining a configuration before deformation and a reference configuration when calculation is started; (b) selecting a limited number of nodes in the parameterized middle surface lambda and determining a local subdomain omega s of each node; (c) calculating a shape function phi I in a definition domain of each node and calculating a derivative of the shape function; (d) determining Gauss integral points of all nodes, calculating a numerical integral and assembling a stiffness matrix; (e) assembling a node mass matrix and a viscosity matrix; and (f) determining the number of cycles according to the simulation time t and the set time step interval delta t to cycle the following steps for t/delta t times: calculating a rotated global stiffness matrix, implementing constraints on the global stiffness matrix, the node mass matrix and the viscosity matrix, obtaining and solving a system linear equation set according to time integral to obtain nodal displacement, implementing meshless collision detection and a response algorithm to modify the nodal displacement, and generating the displacement of all sampling points of each time step after re-sampling.

The invention provides a rotor-rotor. The nonlinear dynamics analysis method for the bearing system comprises the following steps: inputting calculation parameters; Calculating a system overall mass matrix, a rigidity matrix, a damping matrix and a gyroscopic effect matrix; Calculating unbalanced excitation of the rotor; Calculating the thickness of the bearing oil film at the t moment; And calculating the bearing oil film pressure at the t moment. Judging whether the oil film pressure meets a convergence condition or not; Calculating a bearing friction force and an end leakage flow at a t moment; Calculating the effective temperature and effective viscosity of the lubricating oil at the t moment; And calculating the oil film bearing capacity at the t moment. Newmark-based And algorithm: calculating the vibration response of the rotor system at the t + t moment. And whether the break + t moment reaches a time upper limit is determined. According to the method, the bearing nonlinear oilfilm force solving process based on the finite difference method is embedded into calculation of the rotor vibration response, and influence factors such as lubricating oil rheological properties andbearing bush surface elastic deformation are considered when the oil film force is solved, so that the response calculation is more accurate.

The invention discloses a method for identifying a variable boundary cable force of a medium or long cable. The method comprises the following steps of: performing unit discreteness on the cable, dividing the cable into n units (n is in a range of 40 to 400), and calculating a unit rigidity matrix [K]e and a mass matrix [M]e of each unit according to formulas (1) to (2); then arranging rubber cushion blocks on the cable to form external restraint, wherein the number of the rubber cushion blocks is 2 to 6 and the mounting number of the rubber cushion blocks is determined according to the length of the tested cable; and after the total rigidity matrix [K] and the total mass matrix [M] are determined, solving a characteristic value equation l[K]-omega2[M]l=0 of natural vibration frequency of a cable structure by adopting an iteration method to obtain the cable force T. Under the condition that the cable force is not changed, if the boundary condition of the cable is changed, the frequency of the cable is changed, and the equation of the frequency of the cable and the cable force is changed along with the change of the boundary condition of the cable, so the condition that the frequency of the cable cannot be tested under complex environments is solved, and meanwhile the frequency of the cable is in an interval capable of being tested by the conventional instrument by regulating the boundary condition.

The invention discloses a high-pile wharf foundation pile damage diagnosis method based on structural residual modal force. The method includes the steps that a finite element model of a high-pile wharf foundation pile structure is established, the structure is divided into a plurality of units, and each unit comprises two nodes; an acceleration sensor is arranged on each unit, and modal test data detected under natural environment excitation are recorded and saved; modal parameter recognition is performed on the modal test data, and a low-order modal frequency and a vibration mode of previous orders are recognized; model correction is performed, and a reference finite element model is obtained; under the non-damage and damage condition, a rigidity matrix and a mass matrix of each unit are extracted; and each freedom-degree residual modal force vector in each unit is calculated, when the absolute value of each freedom-degree residual modal force vector in each unit is larger than a set value, it is judged that damage exists, and the position where structural damage is located is positioned according to the nodes corresponding to freedom degrees. Only through low-order modal information generated before and after structural damage, damage diagnosis can be performed under the condition that the structure has single damage and multi-site damage.

The invention discloses a rolling bearing-rotor system damage vibration response quantitative calculation method. The method comprises the steps that the structure parameter and the initial parameter of a bearing-rotor system are acquired; according to the bearing parameters, a five freedom degree bearing model is established, and a bearing stiffness matrix of the bearing-rotor system is acquired; according to the geometric size and the material characteristic parameter of a subcomponent, a finite element model is established, and a rotor stiffness matrix, a rotor gyroscopic matrix, and an equivalent mass matrix caused by a centrifugal force are acquired; a dynamics model of the bearing-rotor system is established; a time-domain integral method is used to solve the bearing-rotor dynamics model, so as to acquire the displacement vibration response of the bearing-rotor system. According to the invention, based on the finite element dynamics model, quantitative calculation can be carried out on vibration response generated by single point or multi-point damage of inner and outer rings of a bearing, and a basis is provided for the analysis and the diagnosis of a fault mechanism of the rotor-bearing system.

The invention provides a vibration analysis method for a uniform section beam structure. The method comprises the steps that geometric size characteristics of the beam structure are extracted, a displacement field of the beam structure is separated to be in-section displacement and axial displacement; fitting is performed on the in-section displacement of the beam structure; extension is performedon the axial displacement of the beam structure; the in-section displacement and the axial displacement of the beam structure are combined to calculate integral displacement of the beam structure; strain vectors and stress vectors of an elastic plate structure are calculated; strain energy, a kinetic energy equation and boundary energy of the beam structure are calculated; a structural Lagrange energy function is established to obtain a core mass matrix and a stiffness matrix of the beam structure; an integral mass matrix, an integral stiffness matrix and an overall mass matrix are solved through iterative looping of the core matrix, and then a characteristic equation of the structure is obtained; and a characteristic equation matrix of the beam structure is solved, and inherent frequencyand a vibration mode are obtained through calculation. The method is suitable for the beam structure with multiple boundary conditions and multiple section shapes and is high in precision, fast in convergence, low in calculation cost and simple in calculation method.

The invention provides a method for determining the critical rotating speed of a wet rotor of a multistage centrifugal pump. According to the method, an automatic node division module, a model creating module and a model calculation module are mainly utilized for determining the critical rotating speed, and the data processing is carried out among the modules in a sequence sequentially from the automatic node division module, the model creating module and the model calculation module. Firstly, the automatic node division module creates a geometrical model of a wet rotor system on the basis of an engineering drawing, and in addition, the automatic division of modes is carried out; secondly, the model creating module is utilized for inputting physical parameters of parts such as rotating shafts, impellers, bearings and sealing clearances, and a total mass matrix [M], a total rigidity matrix [K], a total damping matrix [C] and an overall calculation model of a multistage centrifugal pump shaft system are built; finally, the model calculation module is utilized for solving the overall calculation model of the multistage centrifugal pump shaft system, a Campbell chart is drawn, and the required first n step of critical rotating speed is obtained. The method has the advantages that the operation is simple, the engineering applicability is wide, the critical rotating speed of the wet rotor of the multistage centrifugal pump can be calculated under the condition of different structures, the engineering design and the application of the rotor of the multistage centrifugal pump are guided, the design period is shortened, and the production efficiency of the rotor of the multistage centrifugal pump is improved.

Disclosed is a deep-water pier seismic response evaluation method taking water-pier coupling effect into consideration. In the deep-water pier kinetic equation: P=-(M(1)ug(t)+M(2)us(t)), which takes water-pier coupling effect into consideration the M, the K and the C refer to quality matrix, rigidity matrix and damping matrix in the structure respectively, the ug(t) is the seismic oscillation acceleration time interval, the us (t) is the relative-movement displacement time interval of a pier, the u's (t) is the relative-movement speed time interval of the pier, the us(t) is the relative-movement acceleration time interval of the pier, the (M(1)) and the (M(2)) are the rigid-body associated mass matrix and the flexible associated mass matrix under water, and the P is the seismic oscillation water pressure load stressed on the pier. The deep-water pier seismic response evaluation method can be used for anti-seismic design and bearing force evaluation of a deep-water bridge structure under the action of earthquakes. Seismic response analysis of the pier of the deep-water bridge in finite element software can be conveniently performed, the factors, such as nonlinearity, interaction of soil-structural power and the like in materials can be considered during analysis, and the deep-water pier seismic response evaluation method is high in computing efficiency as compared with fluid-solid coupled numerical software and further provides the theoretical basis for the anti-seismic design of the deep-water bridge.

The invention discloses a user selection method in a multi-community multi-user interference channel system in the technical field of communication. The user selection method in multi-community multi-user interference channel system includes: firstly, obtaining an interference channel matrix from other communities to the users in the community, and combing the interference channel matrix into an interference channel matrix of the users of the community; resolving quick response (QR) sorting the interference channel matrix of the users of the community, and obtaining a corresponding upper triangular matrix and postprocessing matrix; using the upper triangular matrix to obtain a user channel mass matrix; obtaining optimal users through the user channel mass matrix; finally, obtaining a postprocessing matrix through the interference channel matrix corresponding to the optimal users. The user selection method in the multi-community multi-user interference channel system is capable of ensuring that the users can select the system, lowering calculating complexity of channel quality information of each user, increasing handling capacity of the system, obviously improving the residual interference after user selection, and improving feasibility of the method in practical application.

The invention discloses a high-efficiency calculating method used for static and dynamic analysis of a flexible mechanism. The high-efficiency calculating method comprises following steps of dispersing the flexible mechanism in a way of taking flexible hinges, flexible beams and connecting blocks as basic units; establishing finite element stiffness matrixes of the flexible hinge units and the flexible beam units; establishing a global stiffness matrix of the flexible mechanism; establishing finite element mass matrixes of the flexible hinge units, the flexible beam units and the connecting block units, and assembling the finite element mass matrixes to form a global mass matrix of the flexible mechanism; applying boundary conditions and loads, establishing a dynamic finite element equilibrium equation, and solving the equation to obtain static parameters and dynamic parameters of the flexible mechanism. According to the invention, on the basis that the computational accuracy is guaranteed, more abundant vibration modal information is revealed, the computational efficiency is improved, the computational amount is reduced, and a high-efficiency mechanical model can be provided for performance analysis, optimization design and real-time closed-loop control analysis of the flexible mechanism and a more complex machinery system comprising the flexible mechanism.

The invention relates to a local constraint damping plate parameter optimization design method based on a genetic algorithm. The method comprises: describing geometric information of the constrained damping fin; establishing a local constraint damping plate parameter optimization design model; performing grid division on the constrained damping plate structure; establishing a rigidity matrix and amass matrix of the entity constraint damping unit, obtaining a rigidity matrix and a mass matrix of a composite unit cut by the boundary of the constraint damping fin, obtaining an integral rigiditymatrix and an integral mass matrix, establishing a finite element dynamic model of the constraint damping plate, and obtaining a modal loss factor of the constraint damping plate; and iterating the design variable through a constraint optimization genetic algorithm until the objective function obtains an optimal value to obtain the geometric parameter of the constraint damping fin. Parameter optimization design of the local constraint damping structure is achieved through a simple and efficient constraint optimization problem genetic algorithm, and compared with a traditional gradient-based optimization method, the local constraint damping structure parameter optimization design method has the advantages that a global optimal value can be found more easily, and falling into a local extremevalue is avoided.

The invention discloses a temperature field and thermal circuit direct coupling-based motor heat analysis method. Part of parts of a motor are modeled by adopting a finite element method, and other parts are modeled by adopting a thermal circuit method. A temperature field is related to a thermal circuit through an equivalent temperature boundary and an equivalent convection boundary. During solving, a thermal circuit part is regarded to consist of one-dimensional finite element units, and two connected boundaries are regarded as two boundary units. Finally a unit stiffness matrix, a unit load matrix, a unit mass matrix and the like corresponding to the one-dimensional finite element units and the boundary units are superposed to a global stiffness matrix, a global load matrix and a global mass matrix, and the temperature field and the temperature distribution in the thermal circuit are worked out at the same time through a method for solving a global linear equation set. According to the method, the advantages of the finite element method and the thermal circuit method in the motor heat analysis are combined, so that sufficient calculation precision can be ensured and the calculation speed can be remarkably increased.

The invention discloses a vibration analysis method of an elastic plate structure. The method includes the steps that the Carrera high-order interception technology is utilized for conducting fittingon the thickness-direction displacement of the elastic plate structure; the two-dimensional improved Fourier series is adopted for conducting full-solution-domain expansion on the plane displacement of the elastic plate structure; the overall displacement of the elastic plate structure is obtained through calculation based on the cross-section plane displacement and axial displacement of the elastic plate structure; the strain vector and stress vector of the elastic plate structure are calculated; a strain energy and kinetic energy equation of the elastic plate structure is calculated, and a virtual spring boundary is set to obtain boundary energy; a structural Lagrangian energy functional is established, and a kernel mass matrix and a stiffness matrix of the elastic plate structure are obtained through calculation; the overall mass matrix and stiffness matrix and the characteristic equation of the structure are obtained through an iterative loop kernel matrix; the inherent frequency of the elastic plate structure is calculated, and the vibration mode of the structure is output according to the feature vector. The method is suitable for elastic plate structures with multiple shapesand multiple boundary conditions, high in precision, fast in convergence and low in calculation cost.

The invention relates to an odor recognition method and device based on an electronic nose and an electronic nose system. The odor recognition method based on the electronic nose comprises the following steps: obtaining detection data of a plurality of odor samples collected by the electronic nose system; decomposing the detection data of each odor sample, so as to obtain an adsorption mass matrixof each odor sample, an adsorption amount scaling matrix of odor molecules of each odor sample on each sensor in the electronic nose system and an odor molecule characteristic matrix; constructing anabstract odor factor diagram of each odor sample separately according to the adsorption mass matrix, adsorption amount scaling matrix and odor molecule characteristic matrix of each odor sample; calculating similarity between abstract odor factor diagrams of two odor samples; and recognizing whether two odor samples are the same odor sample or not according to the similarity between abstract odorfactor diagrams of two odor samples. The odor recognition method based on the electronic nose has the advantages of simple pretreatment, short detection period and low detection cost, and can realizehigh-accuracy identification of different odor samples with high similarity and complexity.

The invention relates to a component model order reduction method facing to product level simulation, and belongs to the CAD computer aided cooperative product simulation technology field, which is characterized in comprising following steps: using ANSYS software to establish a three-dimensional mesh module of the component and calculate modal, and extracting mass matrix and stiffness matrix of the component model; then using Mathematica software and combining an order-reduction algorithm in a finite element analysis to reduce the component model provided with n-dimensional vector into the component model consisted of m modals according to the gained the stiffness matrix and mass matrix, and a state of the structure in a maximum deformation in a setting typical load and a state in system balance. The invention improves product level simulation speed of complex products, improves a reuse degree of simulation data, and is simply operated, and easy to realize.

The invention discloses a method for detecting scouring depths of a soil body around a marine pile foundation. The method comprises the steps: (1) a pile-soil system is built; (2) the pile foundationis divided into n joints through a concentrated mass method to be numbered, the joints are connected through massless elastic rods with the length being d, each joint and a lower connecting rod serveas a unit, and the rod length d serves as the unit thickness; (3) the soil body around the foundation is layered, the thickness of each layer is the same as the unit thickness, namely d, the soil bodyaround the foundation is simplified to be massless spring constraint around the joints, and the elastic coefficient is determined; (4) an overall rigidity matrix and a mass matrix under the pile-soilsystem are built; (5) the inherent frequency and vibration modes of all orders of the pile foundation under the different scouring depths are detected; and (6) the rigidity correction coefficient isobtained through a cross-model and cross-mode method (CMCM method), the joints, namely damaged units, corresponding to mutation positions of the correction coefficient are found, the number of the units between the damaged units and pile foundation units on the mud surface is determined, and the range of the scouring depths is determined by multiplying the number of the units and the unit thickness.