63 results about "Modal superposition" patented technology

The invention relates to a control-orientated large antenna modeling method which comprises the steps of ansvs modal analysis, relevant vibration mode selection, modal parameter calculation, input and output matrix conversion, decomposition of each order of modality, calculation of the norm of each order of modality, modal polycondensation and modal superposition. The method has the advantages that due to the fact that antenna flexibility information is established in a control model, the model is closer to the reality and pointing error calculation is more accurate; due to the fact that a rigid model and a flexible model are both in a decoupled state, rigid corners and flexible deviation can be output by the rigid model and the flexible model respectively, and output processing can be conducted respectively.

The invention discloses a blade vibration response analysis method based on fluid-solid interaction. The blade vibration response analysis method comprises the following steps of: firstly, carrying out unsteady analysis on a flow field in a blade flow channel by adopting a nonlinear harmonic method to obtain unsteady load distribution on the surface of a blade, and extracting a load correspondingto a key frequency by adopting Fourier transform to obtain a pneumatic exciting force borne by the blade; secondly, carrying out fluid-solid interaction analysis on the blade and the flow field in theflow channel of the blade, analyzing aerodynamic work applied to the blade by the aerodynamic force when the blade vibrates, and acquiring modal aerodynamic damping ratios of all orders of vibrationof the blade in the flow field according to an energy equivalence principle; and finally, loading the aerodynamic exciting force and the modal aerodynamic damping ratio of each order onto the blade, and performing vibration response analysis on the blade by adopting a modal superposition method. The blade vibration response analysis method can efficiently and accurately analyze the vibration response of the blade under the action of the unsteady aerodynamic force, and provides support for the safety guarantee and design work of an engine.

The invention discloses a turbine last-stage long blade torsional vibration stress obtaining method based on finite elements, relates to the field of turbine design, and aims to solve the problem that a dynamic stress value obtained in the prior art cannot predict the safety of a turbine last-stage blade when a shafting is subjected to torsional vibration. Due to the fact that the torque value T of the shafting is closely related to long blade dynamic stress distribution caused by torsional vibration when a power grid is in transient imbalance, finite element solving is conducted on the stress of the whole circle of blades and the corresponding rotor structure at the working rotating speed; a stress-strain distribution value of each node is obtained, and first n-order frequencies f1-fn of the system are extracted by utilizing a Lanczos method; and the torque value T of the shafting is applied to the system as excitation when the transient state of the power grid is unbalanced, a modal superposition method is applied, and the dynamic stress value of the last-stage long blade is obtained. The dynamic stress value obtained through the calculation method can predict the safety of the turbine last-stage blade when the shafting is subjected to torsional vibration, and therefore accidents are avoided.

The invention relates to a wind turbine tower stress state calculation method based on a modal superposition method, Firstly, the finite element model of the tower is established, then the truncated modal matrix of the tower is calculated by the finite element method, and the principal vibration coordinates of the tower are calculated according to the real-time vibration values at the monitoring points. Finally, the real-time stress state of the tower is calculated by the modal superposition method. Using this method, the stress states of the whole tower and flange bolts can be calculated quickly according to the real-time vibration values of the finite vibration measuring points of the tower. The method has the characteristics of high calculation accuracy and fast calculation speed, and can meet the requirements of real-time online calculation.

The invention discloses a vibration noise numerical simulation method for a piston engine. The method includes: establishing a three-dimensional entity simulation model and a finite element model of the three-dimensional entity simulation model for the plate-type structure on the surface of the piston engine, and performing vibration modal analysis of the plate-type structure on the three-dimensional entity simulation model to obtain a surface modal result set and a surface node coordinate file of the plate-type structure; performing multi-body dynamics analysis on the three-dimensional entitysimulation model in combination with a finite element model to obtain a plurality of different exciting forces of the piston engine; applying different exciting forces to the plate-type structure ofthe three-dimensional entity simulation model, and calculating dynamic response results of the plate-type structure under different exciting forces by utilizing a modal superposition principle; solving a frequency range requirement of an acoustic physical quantity according to the acoustic boundary element model, and performing roughening processing on the finite element model to obtain an envelope surface grid and a node coordinate file; endowing the dynamic response result to boundary element grid nodes of the node coordinate file, and calculating and obtaining acoustic physical quantity ofacoustic radiation of the plate-type structure.

The invention aims to provide a demonstrating instrument for a simply supported beam vibration experiment. In a physics teaching process, vibration of an infinite-degree-of-freedom object is usually demonstrated through vibrations of simply supported beams or cantilever beams. The simply supported beams in the demonstrating instrument vibrate under vibration excitations of vibration exciters, when the vibration excitation frequency equals to an inherent frequency of a specific phase, the beams resonate, and the vibrating form is approximate to a corresponding principal vibration mode. When the vibration excitation frequency of the vibration exciters is increased slowly, variation of the beams from a first-phase principal vibration mode to a second-phase and a third-phase principal vibration mode can be shown. The demonstrating instrument for the simply supported beam vibration experiment has the advantages that by amplifying displacement and vibration of the simply supported beams by directly demonstrating the principal vibration modes in various phases of the simply supported beams, experimental explanation in modeled teaching for the infinite-degree-of-freedom object vibration is facilitated, and by comparing and observing the multi-phase vibration modes, understanding to modal superposition on vibration is enhanced.