192 results about "Rigidity matrix" patented technology

The invention relates to a pneumatic elastic analytical method, and provides a pneumatic elastic mechanical characteristic analytical method of a hypersonic speed aircraft in thermal environment. According to the method, the piston theory is used for carrying out frequency domain nonsteady aerodynamic calculation on a full-aircraft finite element model of the hypersonic speed aircraft; on the basis, the pneumatic thermal effect on the model in the hypersonic speed thermal environment is considered; the weak coupling effect of pneumatic thermal input in aerodynamic input and elastic force input is ignored; only the structure temperature steady-state characteristics under the pneumatic thermal load effect are considered; after the steady aerodynamic calculation, the thermal flux density on the surface of the aircraft is obtained by adopting a reference enthalpy method; further, the steady temperature distribution on the surface of the aircraft is calculated; the practical equivalent rigidity matrix of the structure at the moment is obtained; and the critical flutter speed is calculated by an engineering method. The pneumatic elastic mechanical characteristic analytical method has the advantages that the pneumatic elastic analytical problem of the hypersonic speed aircraft in the pneumatic thermal environment is solved, and the pneumatic elastic performance of the hypersonic speed aircraft is improved through flutter speed analysis.

The invention provides a five-axis side milling machining cutter path smoothing method. The method comprises calculating the initial cutter location, and calculating the machine tool turning axle angle corresponding to the direction of a cutter axis through a dynamitic model of a specific machine tool; performing interpolation for the machine tool turning axle angle of the initial cutter location and the cutter nose point location, and obtaining a cutter nose point location trajectory and a machine tool rotation angle change curve; according to the cutter nose point location trajectory and the cutter axis vector, showing a side milling machining cutter path; calculating the rigidity matrix, corresponding to the cutter path, of the machine tool rotation angle curve; according to a differential evolution algorithm, calculating the point that the distance between the point to the cutter enveloping surface is shortest among the points on the design surface; and according to a weighted least square method, establishing a five-axis side milling machining cutter path smoothing model, and obtaining an optimized the initial cutter location and the cutter nose point location curve and a smooth machine tool rotation angle curve after solution. The five-axis side milling machining cutter path smoothing method solves the problem about smoothing and geometric deviation control of the five-axis side milling machining cutter path, and is suitable for five-axis side milling machining on a free form surface, a ruled surface or a curved surface similar to the ruled surface.

The invention relates to a three-directional static rigidity synchronous testing system for a machine tool, and belongs to the technical field of static rigidity detection of the machine tool. The system comprises a load measuring subsystem, a three-directional stressing device, a displacement measuring subsystem and a data processor. The input end of the three-directional stressing device and the input end of the displacement measuring subsystem are connected with a main shaft of the machine tool, the output end of the three-directional stressing device is connected with the input end of the load measuring subsystem, and the output end of the displacement measuring subsystem and the output end of the load measuring subsystem are connected with the input end of the data processor. The testing system can apply load which is at certain angles with the X-axis, the Y-axis and the Z-axis of a machine tool coordinate system, and can measure continuously changing data of the load and deformation of the machine tool along three directions at the same time. After the data are processed by data processing programs, a continuously changing curve of nine Kig components in a 3*3 order static rigidity matrix can be obtained.

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 relates to a kinetic parameter determination method of an extended tooth contact considered crack gear rotor system. The method comprises the following steps: obtaining a basic parameter of a healthy gear and a basic parameter and a crack parameter of a crack gear; establishing a gear meshing rigidity model, which comprises matrix rigidity, of the gear; calculating the matrix rigidity of a driving wheel of the gear and the matrix rigidity of a driven wheel of the gear by a finite element method; determining a gear matrix rigidity correction coefficient of the meshing rigidity model which comprises the matrix rigidity; determining the gear tooth deformation of the gear by a method that a gear transferring error is solved to obtain extended tooth contact considered gear time varying meshing rigidity; obtaining the basic parameters of a shaft and a bearing of a gear rotor system; obtaining a rigidity matrix K of the gear rotor system; and according to the rigidity matrix K of the gear rotor system, constructing an extended tooth contact considered rotor system vibration response analysis model, and determining a system vibration response result of the healthy gear and the crack gear.

A fiber-reinforced-plastic (FRP) composite material R region ultrasonic inspection model establishing method is disclosed and belongs to the technical field of composite material ultrasonic inspection. The method comprises the following steps: measuring the geometrical dimension and the density of an FRP composite material R region sample; dissecting and polishing the R region sample cross section and observing the microstructure, concretely observing the unidirectional ply thickness, ply sum and fiber paving sequence; measuring the acoustic velocity of the FRP composite material unidirectional plate sample and performing inversion calculation on the elasticity rigidity matrix; calculating the corresponding Bond transformation matrix of an optimal position in the R region, and performing rotation transformation on the elasticity rigidity matrix; and setting ultrasonic inspection probe parameters and coupling medium material characteristics, so as to finish model establishment. The method gives consideration to the FRP composite material anisotropy, and also realizes quantitative description on the multilayer structure and the curved-surface shape elasticity characteristic. The model can be utilized for performing simulation calculation on FRP composite material R region ultrasonic inspection, and support is provided for researching sonic propagation law and improving inspection quality.

A method for analyzing a torsional vibration inherent characteristic of a planet gear transmission system comprises the following four steps: (1) carrying out mathematical modeling on pure torsional vibration of a single planet row with damping by using an Lagrangian equation; (2) analyzing the inherent characteristic of the transmission system; (3) verifying the influence of the damping on a fixed frequency through multigroup calculation; and (4) establishing a general matrix for the planet gear transmission system and carrying out modeling simulation verification through instance value calculation and simulation X. Through the adoption of the invention, an obtained damped natural vibration differential equation in the form of a parameterized matrix (a rigidity matrix, a damping matrix and a connecting matrix) in the planet transmission system is general; corresponding matrix forms are directly selected for corresponding parts according to different connecting structures and planet gear system parameters to construct an integral system matrix; and after parameters are brought in, the inherent characteristic of the transmission system is rapidly and accurately analyzed.

The invention discloses a deflation modeling method of a micro-electronic-mechanical-system (MEMS) which contains a plurality of input ports. A three-dimension solid model of the structure is established according to the parameters of structure design, modal analysis is carried out by using a finite element method, the quality and the rigidity matrix of the structure is extracted from analysis results, and a second order dynamics action equation of the structure is converted into a first order state equation after being established; an input matrix B is uniformly splitted into k blocks by rows to obtain the state equation of the structure after splitting; deflation is carried out to the application subblock of the (i)th sub-system to obtain the macro model state equation of the (i)th sub-system; the integral macro model of the original system can be obtained after the macro models of all the sub-systems are superposed according to output. The method speeds up the MEMS system level modeling and simulation based on the macro models, thus improving the design efficiency of the MEMS.

The invention provides a method for predicting the effective stress relaxation coefficient of a polymer matrix composite.The method includes the steps that firstly, a linear viscoelatic material constitutive equation in a time intra-domain integral form is established based on the Boltzmann superposition principle; then the effective stress relaxation rigidity of the polymer matrix composite formed by periodic unit cells is defined; then a mesomechanics model for solving an effective stress relaxation rigidity matrix of the polymer matrix composite is established based on the variation asymptotic homogenization theory; finally the effective stress relaxation rigidity of the polymer matrix composite is predicted based on the established mesomechanics model.According to the method, attributes of different materials in different directions can be obtained in the one-time solving process, and compared with a method in which rerunning is conducted under different loading conditions, the method is simpler, more convenient, more efficient and rapider.The calculated effective stress relaxation coefficient is consistent with the precision of a wave function, no more approximation relations need to be introduced, calculation precision is higher, and the strength and service life of the polymer matrix composite are predicted more accurately.

The invention discloses an electric main shaft system modeling method taking features of combination portions into consideration. According to the method, first of all, based on a frequency response function method, the rigidity of the combination portion of an electric main shaft system is identified by use of a hammering experiment, then a finite element model of a main shaft-handle-cutter system is established through the mode of adding and deleting a transition unit at the tail end of a main shaft and a handle, and finally, bearing rigidity, and a rigidity matrix of a main shaft-bearing combination portion and a rigidity matrix of a main shaft-handle-cutter combination portion which are obtained through identification are added to the rigidity matrix of the electric main shaft system so that a complete electric main shaft system kinetic equation is obtained. According to the invention, the rigidity of the combination portions are identified by use of an experiment method, and a theoretical model of the electric main shaft system is established with the influences of the combination portions are taken into consideration, so that the influence rules of the rotating speed, the bearing rigidity, the rigidity of each combination portion and the like for the dynamic features of the electric main shaft system can be simultaneously analyzed. The method can provide guidance for design and application of an electric main shaft and also provides a theoretical basis for prediction of the cutting stability of the electric main shaft system.

The invention provides an orthotropic dielectric fluid factor and fracture parameter inversion method. The method comprises the following steps: deducing a rigidity matrix of an ortho-symmetric anisotropic fracture medium by using a vertical transverse isotropic medium under a dry rock background according to fracture weakness; with utilization of hypotheses of weak anisotropy and small fracture weakness, deducing a new expression of weak anisotropy approximate rigidity of a saturated fluid rock in an orthogonal medium by combining an anisotropy Gassmann equation; acquiring a PP wave linearized reflection coefficient for fluid and fracture parameter decoupling in the orthogonally symmetrical weak anisotropic medium by combining stiffness disturbance and scattering theories; and with logging information as prior information, realizing elastic impedance pre-stack inversion changing with offset and azimuth angle by using a partial incident angle stacked by azimuth seismic data under Bayesian framework. According to the invention, Reliable results can be provided for fluid identification and fracture characterization; and technical supports are provided for seismic wave propagation research, oil and gas development and seismic disaster prevention.

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.

For acquisition of workpiece dynamics parameters and rapid prediction of milling chatter stability considering material removal and cutting tool position variation causing the variation of the workpiece dynamics parameters in the thin-walled workpiece milling process, the invention provides a method for acquiring time-varying dynamics parameters of a workpiece through degree-of-freedom reduction and matrix dimensionality reduction. The method comprises the steps of: utilizing a finite element to obtain quality and stiffness matrixes of the workpiece; reducing the dimensionality of the qualityand stiffness matrixes of the workpiece through carrying out degree-of-freedom reduction and matrix dimensionality reduction; and finally, acquiring dynamics parameters of the workpiece at different tool position points rapidly by adopting a numerical calculation method, and performing stability prediction.

The invention discloses a double-nut planetary roller screw dynamics research method based on elastic deformation. The method comprises the following steps: S1, building a double-nut planetary rollerscrew spring quality system which comprehensively considers the elastic deformation, inertia force and pre-tightening force according to the structural features of a double-nut planetary roller screw;s2, calculating an adjoint matrix and a rigidity matrix of the spring mass system; s3, establishing a stress-deformation-motion parameter coupled double-nut planetary roller screw elastic kinetic equation; s4, establishing a rigid body motion equation of the lead screw and the pin roller; and S5, solving the elastic kinetic equation in the step S3 in combination with the rigid body motion equation of the lead screw and the pin roller in the step S4. According to the research method, a stress-deformation-motion parameter coupled double-nut planetary roller screw elastic kinetic equation is provided, and the pre-tightening force, deformation, load distribution and motion state of the mechanism under different use working conditions are obtained by solving the equation.

The invention discloses a temperature parameterized reduced-order modeling method for a micro-electromechanical system, and belongs to the field of micro-electromechanical system design and model order reduction. The method comprises the following steps: extracting quality, rigidity and temperature stress rigidity matrixes, and establishing a two-order dynamical equation related to temperature; constructing an orthogonal mapping matrix V; and projecting the primary two-order dynamical equation to a subspace in which the orthogonal mapping matrix V is positioned so as to acquire a temperature parameterized low-order model. The reduced-order method can greatly reduce the freedom scale of the primary model through an order reduction algorithm so as to improve the system-level modeling and simulating speed based on the reduced-order model. Simultaneously, by adopting the matrix matching principle, transfer functions of the reduced-order model and the primary model can be approximate better so as to have higher precision. During order reduction, a projection matrix irrelative with parameters can be generated, and finally, a temperature parameter in the primary system is reserved in the low-order model.

According to the method, the least square fitting surface function is established by utilizing the linear function and the consistent tight support radial basis function, so that the simulation of theelastic deformation of the wing is realized, and the problem of deformation surface volatility during displacement transmission of a traditional interpolation method is solved. On the basis of staticaeroelastic calculation, a model analysis solving method for aerodynamic load design sensitivity based on an iteration mode is provided and comprises a direct method and an accompanying method, the algorithm avoids damage to an original rigidity matrix, meanwhile, calculation efficiency is high, and the requirement of engineering practice is met.

The invention discloses a compliant mechanism generation method based on zero depletion grid surface continuous deformation. The compliant mechanism generation method comprises the following steps: firstly, configuring initial component layout, initializing a calculation layer based on isogeometric analysis, applying load and constraint on isogeometric unit control points of the calculation layer,initializing iterative parameters of a moving asymptotic method, and optimizing iteration; calculating the volume of the triangular mesh, mapping the topology described by the upper triangular mesh to a lower calculation layer, calculating the projection value of a control point, and assembling an overall rigidity matrix; calculating a target function value of the structure response, solving thesensitivity of the volume, and inputting the sensitivity into an optimizer to obtain an updated coordinate value; judging triggering conditions of grid refinement, grid splitting and grid re-divisionoperation according to the updated vertex coordinate value, completing grid re-update, calculating non-control vertex update coordinates, updating the triangular grid curved surface shape, and completing one iteration; repeating iteration until convergence conditions are met. According to the method, structural response calculation and sensitivity analysis in the topological optimization process are reliably realized.

The invention provides a numerical analysis method for the connection between three-dimensional and two-dimensional finite element units, and aims to save time and reduce analysis cost by replacing part of a test result with numerical simulation. The numerical analysis method is characterized by comprising the following steps: (1) constructing a three-dimensional unit and a two-dimensional unit at actual structure positions respectively, endowing the three-dimensional unit with a simulated rotating freedom degree at the connection between the three-dimensional unit and the two-dimensional unit, and establishing a connection relationship between the two-dimensional unit and a new three-dimensional unit by virtue of a rigid body element; (2) creating a card required by structure analysis according to a connection form and a constraint relationship of the rigid body element; (3) creating a unit rigidity matrix according to the card required by analysis, assembling the unit rigidity matrix with other unit rigidity matrixes of the structure to form an overall rigidity matrix, and creating structure deformation and unit stress distribution according to a structure load and a boundary condition.

The invention discloses a parameterized static super-unit construction method. The unit reduces the model freedom by the substructure method, then parameterizing various sizes of the structure; fits rigidity matrix K and strain matrix B to construct the super-unit that has a small number of nodes, so that considerable computing time is saved for easy optimization and the guaranteed accuracy of calculations. Based on the construction method for the super-unit, various super-units with computational complexity greatly reduced are constructed.

The invention provides an automobile drive axle vibration simulation analysis method. The method comprises the following steps: 1) establishing a main speed reducer transmission model of an automobiledrive axle through transmission analysis software; 2) extracting positioning size information of a bearing center point of a main speed reducer; 3) establishing a shell finite element model of a drive axle shell through finite element software; 4) generating a mass and rigidity matrix of a bearing center point; 5) importing the mass and rigidity matrix of the central point of a bearing into transmission analysis software; 6) outputting dynamic displacement information of the bearing center point under different working conditions; 7) calculating the shell vibration response under the bearingload. Finite element software and professional transmission analysis software are combined, the test amount is reduced, the test period is shortened, a simulation model is used for optimizing and improving the drive axle, the improvement effect is checked before formal improvement and implementation, and the production cost of enterprises is saved.

The invention provides a method for calculating load distribution of composite bolt connection by considering clearance and friction influence and relates to a composite bolt connection technique. The method comprises the following steps: constructing a structure node unit model; inputting a geometrical parameter, a material parameter and a boundary condition to complete the construction of a bolt connecting model; calculating node displacement on the basis of the constructed bolt connecting model; accordingly calculating the bolt load distribution. According to the method, a bolt connecting model structure is generated on the basis of an EXCEL frame; the following three conditions are considered for the unit stiffness matrix and the corresponding equivalent load vector of the bolt: the influence caused by clearance and friction is not considered, the influence caused by clearance is considered and the influence caused by clearance and friction is considered; the method has the advantages of high calculation efficiency of spring model and high modeling efficiency of finite element method; the problems of low calculation efficiency and complex modeling on the basis of consideration for the influence caused by clearance and friction of the traditional finite element method can be avoided; compared with the traditional spring model, the method is higher in modeling efficiency and is short in model modification time.