935 results about "Modal analysis" patented technology

The present invention provides, among other things, automatic identification of near-redundant units in a large TTS voice table, identifying which units are distinctive enough to keep and which units are sufficiently redundant to discard. According to an aspect of the invention, pruning is treated as a clustering problem in a suitable feature space. All instances of a given unit (e.g. word or characters expressed as Unicode strings) are mapped onto the feature space, and cluster units in that space using a suitable similarity measure. Since all units in a given cluster are, by construction, closely related from the point of view of the measure used, they are suitably redundant and can be replaced by a single instance. The disclosed method can detect near-redundancy in TTS units in a completely unsupervised manner, based on an original feature extraction and clustering strategy. Each unit can be processed in parallel, and the algorithm is totally scalable, with a pruning factor determinable by a user through the near-redundancy criterion. In an exemplary implementation, a matrix-style modal analysis via Singular Value Decomposition (SVD) is performed on the matrix of the observed instances for the given word unit, resulting in each row of the matrix associated with a feature vector, which can then be clustered using an appropriate closeness measure. Pruning results by mapping each instance to the centroid of its cluster.

The invention discloses a method for simulating the blade flutter boundary of an aviation turbine engine, which is based on the principle of energy law and adopts a weak coupling method to design a flutter forecasting method, thus obtaining the blade flutter boundary of the engine by pneumatic damping value. The method comprises: first, a solid model of a blade is set up; then, modal analysis is carried out on the blade; after that, a flow field model of the blade is set up; the vibration displacement of the linear interpolation blade can be obtained, grid files needed by flow field analysis are generated by adopting multilayer dynamic mesh processing, a dynamic mesh module is invoked to obtain the parameters in the flow field, pneumatic damping is acquired under every working condition, and finally, the flutter boundary can be obtained. Based on the one-way weak coupling, the method greatly simplifies the calculation, saves the calculation cost, and can realize the pneumatic damping calculation under any frequency and different flow field states, thus having good engineering applicability.

A test and analysis system of digital machine process-dynamics character comprises hardware prepared as arranging acceleration transducer at tail end of cutter, connecting hammer and said transducer to electric charge amplifier being connected to data collector and carrying out data transmission with computer by said collector; and software formed by man-machine interactive boundary and module of data collection, data play-back, hammering test, transmission function analysis, parameter identification, noise test and analysis.

The invention provides a method and system used for monitoring the vibration states of impellers of wind generating sets. The method includes the steps that the vibration acceleration of a predetermined measuring point on a vane of each wind generating set in at least one direction is detected according to a preset detection period, data of operating parameters of at least one of the wind generating sets are synchronously acquired, and the acquired data of the operating parameters of the set and the detected vibration acceleration data are recorded; data sets of recorded operating parameter data and recorded vibration acceleration data exceeding the preset amount are selected; according to the operating parameters of the wind generating sets, vibration acceleration data detected when the wind generating sets are in abnormal working conditions are removed from the data sets; operating mode analysis is carried out on the vibration acceleration data detected at the measuring points of the vanes, at least one of the inherent frequency, the damping ratio and the vibration mode of each vane in the operating state is extracted, and whether the impellers of the wind generating sets break down or not are determined according to the extracted inherent frequency, damping ratio and vibration mode.

The invention discloses a method for optimally designing dynamic property of a complete machine tool, which comprises the following steps of: establishing a complete machine tool entity parameterized model, simplifying the structure according to the analysis requirement on the dynamics and the structure characteristic of the machine tool; and guiding the simplified entity model into a finite element analyzing software ANSYS / Workbench for grid division to obtain a complete machine finite element model. The statics analysis is carried out through the ANSYS / Workbench to obtain a complete machine prestress field, and the mode of the complete machine tool under the prestress field is obtained through the mode analysis. The complete machine tool dynamics response of a main shaft, caused by a cutting force, under different rotating speeds is obtained through resonance response analysis on the complete machine tool, and the reference is provided for the searching of the dynamics thin link and the optimization design. Finally, by using the parameterized analysis method, the rule of influencing the complete machine tool dynamic property by the structure quality and the rigidity parameter is obtained, and the dynamic rigidity thin link is obtained and optimally designed.

The invention discloses a method for analyzing fluid dynamics and structural mechanics of wind generator blades, which comprises the following steps: combining CFD and CAE methods, determining each parameter of an impeller model by adopting the momentum blade element theory, designing an entity model of the blade, establishing a three-dimensional model of a windmill blade, a hub and a peripheral wind site based on a Gambit software platform, meshing the model by adopting a partial structuring method, setting a proper boundary condition, calculating the performance of a finite element based on a Fluent software platform, extracting the blade torsion and calculating the blade power and the blade efficiency, establishing a blade structural model based on an ansys software platform and meshing the blade structural model, applying load and restraint condition to the blade structural model, analyzing the mode of the blade structure, performing equal torque treatment for pressure distribution acquired by the Fluent software platform, applying pressure surface load to the ansys software platform, calculating the structural mechanics characteristics of the wind generator blades, and extracting blade deformation and stress distribution characteristics.

The invention relates to an aeroelastic stability fluid-structure interaction prediction method of turbo-machine changed interblade phase angles, which predicts the aeroelastic stability of a turbo-machine through the modal pneumatic damping ratio of different interblade phase angles by adopting an energy method. The method adopts the modal analysis containing prestress on established single-sector finite element models, realizes the vibration displacement transfer on the fluid-structure interaction interface through a data transfer method, adopts the dynamic mesh technology for obtaining mesh files taking the interblade phase angles into consideration, is used for unsteady computation fluid mechanic analysis of Junction Box modules in CFX, further obtains the modal pneumatic damping ratio of each interblade phase angle, and is used for predicting the aeroelastic stability. The method based on the fluid-structure interaction fully utilizes the cutting edge technology of the computational structural mechanics and the computation fluid mechanics, ensures the computation precision in each sub system, and improves the computation efficiency through the division of a fixed region and a movable region. The invention has good practical value and wide application prospects in the technical field of turbo-machine simulation.

A real-time simulation method and system for large deformations is provided. Green's nonlinear strain tensor accurately models large deformations. Modal analysis based on a linear strain tensor has been shown to be suitable for real-time simulation, but is accurate only for moderately small deformations. In the present invention, the rotational component of an infinitesimal deformation is identified, and traditional linear modal analysis is extended to track that component. And the invention develops a procedure to integrate the small rotations occurring at the nodal points. An interesting feature of the formulation is that it can implement both position and orientation constraints in a straightforward manner. These constraints can be used to interactively manipulate the shape of a deformable solid by dragging / twisting a set of nodes. Experiments show that the technique runs in real-time even for a complex model, and that it can simulate large bending and / or twisting deformations with acceptable realism.

The invention discloses a multi-crack damage identification apparatus and method for a cantilever flexible beam. The apparatus comprises a flexible beam, a mechanical clamping device, a detection device, a vibration exciter, a signal generator, a power amplifier, a fiber Bragg grating demodulator and a computer. One end of the flexible beam with multiple cracks is fixed through the mechanical clamping device; a multi-channel FBG optical fiber sensor group is adhered on the flexible beam and is evenly distributed along the length direction of the flexible beam; a signal generated by the signal generator is amplified by the power amplifier and then enters the vibration exciter; the vibration exciter excites low-order mode vibration of the flexible beam; the vibration results in curvature changes at measurement points of each sensor of the beam; the sensors input the curvature changes into the fiber Bragg grating demodulator in the form of wavelength changes; a demodulated signal enters the computer for modal analysis of the flexible beam, drafting of a modal curvature curve, calculation of damage indexes and establishment of a wavelet neural network identification model; and finally, the purpose of accurate identification of the depth and the location of the cracks of the flexible beam is achieved.

The invention relates to a high-speed aircraft lifting surface aerodynamic heating structure multidisciplinary optimization design platform belonging to the technical field of modern high-speed aircraft designs. In the invention, by aiming at the demands of lifting surface heat vibration analysis in an aerodynamic heating environment when a high-speed aircraft lifting surface is designed and considering the positive correlation among aerodynamic heating structures, an aerodynamic heating structure integrated analysis method including aerodynamic heating calculation, transient heat conduction analysis, structural heat model analysis and non-constant aerodynamic force and heat vibration analysis is researched, and the aerodynamic heating structure multidisciplinary optimization design taking the most dangerous heat vibration speed as the constraint and taking the lifting surface structural quality as a target function is researched to achieve the goal of the optimization design on the high-speed aircraft lifting surface. The invention breaks through the problem that the multidisciplinary design optimization is carried out without combining with the influence of three aspects of aerodynamic heating on the structure in the traditional high-speed aircraft design, provides a set of high-speed aircraft lifting surface aerodynamic heating structure optimization design methods and waysand has the advantages of simple scheme and high efficiency.

The invention relates to the use of distributed optical fibre sensors for distributed acoustic sensing, and in particular, modal analysis of distributed acoustic data obtained in-well to monitoring well integrity. By determining one or more acoustic modes corresponding to distributed speed of sound measurements within the wellbore, and analysing variations in the distributed speed of sound measurement it is possible to derive information relating to a formation and / or fluid in the wellbore.

A power system oscillation detection device is provided for use in an electric power system. A plurality of sample signals are acquired from the electrical power system via a plurality of intelligent electronic devices (IEDs) in communication with the power system. The power system oscillation detection device includes a real-time modal analysis module, a real-time mode identification module, and real-time decision and control logic. The real-time modal analysis module calculates modes of at least one of the signals, each mode including mode information. The real-time mode identification module together with the real-time decision and control logic determines, from the mode information, whether there is an undesirable oscillation in the electric power system and activates a remedial action.

The invention belongs to the technical field of mechanical analysis and numerical solution of a three-dimensional structure and relates to a contact analysis method in three-dimensional mechanical finite element model analysis. The method comprises the steps of firstly modeling a target electron device structure; introducing a displacement boundary condition or a stress boundary condition to establish a corresponding geometric structure model; generating a contact relation between parts according to a mutual relation between the parts; then subdividing the established geometric structure model by use of a tetrahedral mesh; generating a joint surface mesh according to a surface mesh in a simulated area contact surface; and finally establishing a finite element general intrinsic equation of a target electron device in consideration of a contact problem by use of a finite element method, solving the equation to obtain a characteristic value and a characteristic vector, and post-processing to obtain a vibration modal frequency and a vibration model. Therefore, the contact analysis in modal analysis is realized and a high-precision numerical calculation result is obtained.

The invention mainly relates to a dynamical joint simulation analysis method of a door system of a rail transit vehicle, and the method mainly comprises the steps as follows: (1) a system is subjected to three-dimensional modeling and a three-dimensional model is converted to a neutral file in a SolidWorks environment to be imported into ADAMS (automatic dynamic analysis of mechanical systems); (2) the modal analysis of a flexible body component is conducted in Ansys, and converted to a neutral file to be imported into the ADAMS to replace a corresponding rigid body model; (3) a simulation model is preprocessed; (4) a system control model is built in Matlab, the door system is subjected to simulation control by an ADAMS / Control module to accomplish the kinematic and dynamical simulations of the whole system; (5) an experimental test platform is constructed, and a motion experimental test of the system is conducted; (6) a simulation result is compared with an experimental result, and the model is modified continuously; and (7) motion simulations of opening and closing a door and simulating a practical operating condition are conducted to search an optimal door control system mode.

The invention discloses a stress sensor based electronic device functional profile feature point displacement field reconstruction method. The method includes: determining a structural parameter and a material attribute of an electronic device functional profile and distribution positions and the number of stress sensors; acquiring a stress value measured by functional profile stress sensors under the action of service loads; establishing a structural finite element model of a functional profile; performing modal analysis on the functional profile; acquiring a modal shape and a stress modal shape of the functional profile; extracting a stress modal shape matrix corresponding to position nodes of the stress sensors; calculating a generalized modal coordinate; extracting a modal shape matrix corresponding to feature points of the functional profile; and reconstructing displacement of the feature points of the functional profile. Based on a modal analysis theory, the method can use stress values measured by the few stress sensors to reconstruct a displacement field of the feature points of the electronic device functional profile in the condition of unknown structural load information, and can direct structural distortion compensation and electrical performance compensation of the electronic device functional profile.

The invention discloses a method for identifying damages of a frame structure. The method comprises the following steps: firstly, testing an undamaged frame structure, and carrying out model modification on an initial discretization model of the frame structure so as to obtain an accurate finite element theoretical model, and calculating a structural modal parameter (omega A0, phi A0); then, testing the damaged frame structure, and carrying out model analysis on the damaged frame structure so as to obtain a modal parameter (omega t2, phi t2); and finally, establishing a direct analysis method damage identification equation, and solving an unit damage coefficient Di (i=1, 2,..., n) by using front n (n is less than or equal to N) order frequencies and vibration mode variation value delta omega r (r=1, 2,..., n) of the frame structure before and after damage so as to achieve the purpose of simultaneously identifying the number, position and size of the damages existing in the whole structure. The method is suitable for the damage identification of a construction frame structure, and has the advantages of less required detection data amount, high efficiency and higher precision.

The invention belongs to the technical field of the low-frequency oscillation on-line detection and analysis in an electric power system and provides a low-frequency oscillation modal analysis method, which is based on wide area phasor metrical information and an empirical mode decomposition method and can carry out the on-line detection and node homology grouping toward the complex low-frequency oscillation of the electric power system. The modal analysis method not only has strong adaptability to the complex waveforms of non-linearity, non-stationarity or those containing non-periodic constituents, but also can carry out phase comparison toward nonsine or cosinoidal inherent modal curves which belong to the oscillation mode of the same electric power system but are slightly different in frequency and realize the homology grouping of the nodes participating in each oscillation mode, thus obtaining the power conversion relation among the nodes and the position of an oscillation center or interface.

The invention provides a power grid dynamic observing method based on PMU (power management unit) data. On the basis of PMU point distribution optimizing and in combination with the network topology information after EMS / SCADA (energy management system / supervisory control and data acquisition) state estimation, dynamic observation of the whole power grid can be achieved, and complete, reliable and real-time information is provided for a power grid advanced application analyzing function. In combination with C / S and B / S architectures, the dynamic monitoring and analyzing results are visually displayed to a dispatcher in a two-dimensional or three-dimensional manner to assist decision making. The method has the advantages that a power grid modal analysis method is combined, the coupling relation of active power and voltage phase angle is considered, the minimal dominating set algorithm is used, and the realized PMU point distribution method can actually and accurately reflect the stable weak areas of the current power grid; the EMS / SCADA data after state estimation is analyzed and correlated with PMU configuration data in a mapping manner to form mixed data, and reliable and accurate data source is provided for subsequent analysis.

The invention relates to a method for analyzing the vibration characteristics of a bearing retainer based on finite elements and aims at solving the problem that no automatic analysis procedure for the vibration characteristics of the bearing retainer is developed at present to prevent the frequency range of resonance of the bearing retainer of an aero-engine. The method is implemented through a step 1 of creating the three-dimensional model of the bearing retainer and saving the three-dimensional model under the working directory set by finite element software, a step 2 of establishing a finite element model and applying the rotating speed of the bearing to the finite element model for performing statics analysis and modal analysis, a step 3 of obtaining the stress and the strain as well as the inherent frequency and the corresponding formation thereof under the action of the rotating speed of the bearing, a step 4 of determining whether the stress and the deformation of the bearing retainer under the action of the centrifugal force meet the design requirements, and the like. The method for analyzing the vibration characteristics of the bearing retainer based on the finite elements is applied to the field of the vibration characteristics of the bearing retainers.

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 an out-of-plane frequency method for testing the cable force of a planar cable rod system, which discloses an out-of-plane frequency method based on the cable force of a pulling cable of an out-of-plane self-oscillation frequency testing planar cable rod system and belongs to the fields of cable force monitoring, state (parameter) identification, health monitoring and the like of the construction phase and the use phase of a cable structure. The method is based on the cable force of the pulling cable of the out-of-plane self-oscillation frequency testing planar cable rod system, and continuous short cables in the planar cable rod system are converted into an out-of-plane long cable, the cable force is determined by measuring the out-of-plane self-oscillation frequency and establishing a cable force-out-of-plane self-oscillation frequency relation formula, and the method concretely comprises the following steps of: 1. carrying out the modal analysis of the finite element model of the planar cable rod system, and determining the out-of-plane calculated length; 2. measuring the out-of-plane self-oscillation frequency of the planar cable rod system; 3. identifying the out-of-plane bending rigidity according to the measured multistage out-of-plane self-oscillation frequency; 4. establishing the cable force-out-of-plane self-oscillation frequency relation formula; and 5. calculating the cable force.

The invention belongs to the technical field of aircraft flying load design, and relates to the improvement on a method for determining a wing structure load when a transportation aircraft drops goods. The method for determining the wing structure load is characterized by comprising the step of initializing aircraft air-dropping goods parameters, the step of analyzing aircraft limited element modals, the step of calculating an aircraft non-steady aerodynamic coefficient matrix, the step of calculating an aircraft air-dropping goods dynamic response, the step of calculating a wing structure load dynamic response, and the step of determining the design load of the wing structure in the process of air-dropping. By means of the improved method for determining the wing structure load when the transportation aircraft drops the goods, the determining precision of the wing structure load is improved, and the safety of the wing structure and the flying safety of the aircraft are guaranteed.

The invention relates to a crack identification method of a main shaft of a boring machine, the method comprises the following steps: the first step: establishing a wavelet finite element model of the main shaft of cracks of the boring machine under the running state; the second step: adopting the wavelet finite element model of the first step to calculate a forward problem solution crack quantitative diagnosis database which takes the first three-order forward whirling frequency as the target, applying the operational mode analysis method to measure the actual forward whirling frequency of the main shaft of the cracks of the boring machine under the running state, utilizing the mixed optimization algorithm of the genetic algorithm and a back propagation neural network to solve, and quantitatively identifying the positions and the severities of the cracks of the main shaft of the boring machine. The method is effective and reliable, is applicable to quantitative diagnosis of the cracks of the main shaft of the running boring machine, can overcome the defect that the common method can only be used for the static state and is suitable for on-line monitoring and diagnosis.

The invention discloses a vibration damping and energy absorption method for an automobile sub-frame, which comprises the steps of (1) performing finite-element analysis to an sub-frame to obtain the quality, the first-order bending mode and the corresponding maximum displacement site of the sub-frame; (2) arranging a mass block with an elastic damping system to damp vibration and absorb energy; and (3) performing modal analysis and experimental verification on the improved sub-frame to correct the elastic damping system and the mass block parameters. The inventive method does not change the current structure of the sub-frame, and arranges the mass block with the elastic damping system in a specific position on the sub-frame to reduce the vibration amplitude by utilizing the principle of resonance energy absorption, so as to reduce the transmission of vibration toward automobile body. The method can also adjust the frequency of vibration damping and energy absorption devices by adjusting the mass of the mass block and the vertical rigidity of the elastic damping system. The inventive method has the advantages of simple structure and not remarkably increased weight and cost, and can maximally damp transmission of the vibration toward the automobile body.

The invention discloses a structural dynamical model modification-based prestress recognition method, and relates to the prestress recognition of pre-tensioning structures. The method comprises the following steps: establishing a finite element model of a structure; converting the boundary condition such as clamped support or simple support into spring support in three or two directions, and applying an axial prestress at the same time; calculating a fixed frequency and a fixed vibration mode of the structure through commercial finite element software; carrying out test and recognition by utilizing a test modal analysis technology, so as to obtain the fixed frequency and the fixed vibration mode of the structure; and recognizing the spring support rigidity and prestress of the boundary at the same time on the basis of a model modification technology. The method is simple, high in recognition precision and convenient to operate; and through considering the influences of the boundary condition, the reliability is high. By taking MAC as a target function, the completeness of the test data is supplemented; the optimization through a genetic algorithm is more beneficial for obtaining the globally optimal solution; and the whole modification model can be automatically driven to carry out solving.

The invention relates to detection equipment for welding spot failure of a whole set of white vehicle body. The detection equipment comprises a white vehicle body welding assembly, a vibration exciter and an acceleration sensor, wherein the white vehicle body welding assembly is fixedly arranged on a rack through a special clamp system; one side of the vibration exciter is connected with a data control and acquisition system; the other side of the vibration exciter is a free end for vibration excitation; the acceleration sensor is attached to a key part of the white vehicle body to be detected by using a magnet; the data control and acquisition system is connected with the acceleration sensor and is used for simply processing the acquired voltage signal and then transmitting data to a microcomputer; the data control and acquisition system and the microcomputer form a data detection and analysis system, i.e. an MIMO (Multiple Input Multiple Output) system; and the MIMO system integrates a signal acquisition system and can be used for modal analysis and damage identification of residual force vector as well as can be used for sampling, analyzing and processing the signal acquired in a current area to obtain an accurate detection result.

Based on principles of wavelet transform and energy spectrum, information entropy, and modal analysis, characteristic quantities of electropolar voltage, current, displacement and sound signal in spot welding procedure are calculated out. A neural network model created is trained through characteristic quantities and nugget area. Comparing the nugget area calculated from neural network model with the area actual measured determines error value, from which the neural network model is adjusted, is carried out until the error is within required region. The invention provides measured result with high accuracy and small error, suitable to online testing and controlling spot welding resistances of allautals and other metal plates.

The invention discloses a harmonic modal analysis method for an offshore wind farm. The method comprises the steps of 1) building a system harmonic model according to an offshore wind farm system, namely a connection relationship between each component and a cable; 2) establishing a network admittance matrix of the system according to the system harmonic model, solving a modal impedance frequency spectrum of the system by utilizing a modal method, calculating a participation factor of each node, and determining a real occurrence position of harmonic vibration; 3) assessing the sensitivity of electric parameters of components of the system; and 4) assessing the sensitivity of design parameters of the system. According to the method, an equivalent model is built according to the parameter of each component of the wind farm, the harmonic performance of the system under different topological parameters, cable parameters, transformer parameters and other parameters is studied by applying the modal analysis method, and the topological design and component model selection of the wind farm can be optimized.

The invention discloses a bolt joint part looseness detecting method and system based on a nonlinear shock excitation feature. The method comprises the following steps: carrying out simulated modal analysis on a three-dimensional model of a test piece, and determining the arrangement positions of a vibration exciter and a sensor of a local part of a bolt joint part; arranging the vibration exciterand the sensor according to the determined arrangement positions of the vibration exciter and the sensor, and determining a vibration excitement parameter of the vibrator exciter according to the simulated modal analysis result of the three-dimensional model; maintaining the vibration excitement parameter unchanged, carrying out preliminary experiment on the same kind of test pieces to obtain a corresponding relation between a bolt pretightening force and a high harmonic scaling factor, and generating a relation data base; and carrying out test on a test piece to be tested to obtain a high harmonic scaling factor, querying the relation data base, determining the bolt pretightening force of the test piece to be tested, and judging whether the bolt joint part of the test piece to be testedis loosen or not according to the bolt pretightening force of the test piece to be tested. The method has the advantages of wide applicability, flexibility and convenience in use, high sensitivity andthe like, implements nondestructive detection, and is suitable for actual production.

The invention relates to a real-time cutting simulation method of a flexible object on the basis of finite element and time-variant modal analysis. The real-time cutting simulation method carries out researches and is implemented mainly by aiming at a real-time interactive soft tissue deformation and cutting simulation algorithm of a virtual surgery. The method comprises the following steps: carrying out voxelization and finite element physical modeling on a simulation domain of a model, carrying out subspace construction on the basis of priori modal analysis, carrying out cutting operation response, carrying out significance analysis and screening on a subspace base vector, and carrying out subspace time-variant effectiveness estimation. The method carries out parallel design on the simulation algorithm and achieves real-time interactive efficiency by virtue of the powerful calculation capability of GPU (Graphics Processing Unit).