7 results about "Modal damping ratio" patented technology

This application provides a method for forced response analysis of an integral bladed disk (IBD), comprising: constructing a finite element model of an IBD sector; conducting disk-coupled resonance analysis of the finite element model to obtain the frequency, mode shape, and relative vibration stress of the IBD blades under one to multiple node diameters, and plotting disk-coupled resonance diagrams; determining the critical node diameter related to the number of rotor and stator blades; determining the frequency order and corresponding critical resonance speed by combining the plotted disk-coupled resonance diagrams and the critical node diameter; performing damping tests on the IBD blades to obtain the frequency order and corresponding modal damping ratios; establishing a full-ring model of the IBD rotor blades and the stator blades before and after them; conducting steady flow field analysis of the full-ring model to obtain steady results as the initial field conditions for unsteady flow field analysis; conducting unsteady flow field analysis to obtain the actual vibration stress of the IBD; and conducting dynamic strength reserve analysis to evaluate the dynamic strength reserve of the high-load IBD under the analysis conditions.

This invention relates to a method for predicting the critical flutter wind speed of long-span bridges based on the L-P perturbation method, comprising the following steps: S1, obtaining the physical characteristics and aerodynamic parameters of the bridge as basic data through wind tunnel tests; S2, establishing the bridge motion control matrix equation based on modal displacement; S3, deriving explicit solutions for the modal frequencies, damping ratios, and modal characteristics of each modal branch based on the L-P perturbation method; S4, iteratively solving the modal frequencies, and directly solving the damping ratio, amplitude ratio, and phase difference on this basis, observing the change of the modal damping ratio ξ with the wind speed U in each direction, and determining the critical flutter wind speed; solving the problem that the existing explicit closed-form solution of the three-degree-of-freedom flutter initiation condition requires multiple iterative calculations of the modal frequencies, damping ratios, and mode shapes, and is difficult to clearly explain the influence of structural and aerodynamic parameters on aerodynamic instability, thus failing to accurately predict the critical flutter wind speed of long-span bridges.

This invention discloses a method for optimizing the multimodal damping ratio of a cable-composite damper-cable-end damper system, comprising the following steps: S1, constructing a coupled system of cable-composite damper-cable-end damper; S2, calculating the damped vibration frequency, damping ratio of each mode, and mode shape of the coupled system; S3, optimizing the multimodal damping ratio of the coupled system. This invention constructs a coupled system consisting of a conventional damper, a damped damper, and a cable-end damper working collaboratively. Then, using the average normalized damping ratio of the multimodal damping ratio as the optimization index, the method systematically optimizes key parameters such as the stiffness and damping of the composite damper, the damping coefficient of the cable-end damper, and its installation position to achieve an overall and balanced improvement in the damping level of each mode.

The invention relates to the technical field of numerical control machining and intelligent manufacturing, and discloses an intelligent machining control method and system for automobile part milling. The method comprises the steps that a vibration signal and stress data are obtained and preprocessed to obtain a time domain sequence; resolving the time domain sequence to obtain a modal damping ratio time-varying characteristic sequence; analyzing rigidity fluctuation and a critical state, and predicting a damping ratio trend to lock an advanced intervention opportunity point; generating a variable parameter control instruction sequence according to the intervention opportunity point; screening an optimal control parameter combination based on an efficiency and life model; and outputting a final flutter suppression signal in combination with real-time vibration feedback. According to the method, the dynamic change of the damping ratio can be tracked in real time, the flutter is accurately intervened in advance, and the production efficiency and the service life of the cutter are both considered while the machining stability is guaranteed.

The present application relates to a kind of transmission line galloping critical wind speed prediction method based on L-P perturbation method, comprising the following steps: S1, the physical characteristics and aerodynamic parameters of transmission line are obtained by wind tunnel test as basic data;S2, establish the motion control matrix equation of transmission line based on modal displacement;S3, explicit solution of modal frequency, damping ratio and modal characteristics of each modal branch is derived based on L-P perturbation method;S4, iteratively solve modal frequency, on this basis directly solve damping ratio, amplitude ratio and phase difference, observe the change of modal damping ratio ξ in each direction with wind speed U, determine the critical wind speed of galloping;The explicit closed solution of the existing three-degree-of-freedom galloping start-up condition needs to be calculated multiple times iteratively on modal frequency, damping ratio and mode shape, and it is difficult to clearly explain the influence of structural parameters and aerodynamic parameters on aerodynamic instability, and the critical wind speed of transmission line galloping cannot be well predicted.

The invention relates to the technical field of finite element analysis, in particular to a viscous damping wall vibration attenuation performance analysis method based on finite element analysis, and the method comprises the steps: building a finite element model of a high-rise building structure, carrying out undamped modal analysis on the finite element model, extracting a mass matrix and a stiffness matrix, reading a modal vector of a dominant modal, and calculating the vibration attenuation performance of the high-rise building structure; calculating the inherent frequency and modal quality of the dominant mode; a simulation experiment is conducted on the finite element model, the equivalent modal damping ratio of the high-rise building structure is obtained, the peak displacement of the finite element model with the viscous damping wall is estimated, the estimation result and the design requirement are compared and judged, and the additional damping ratio is adjusted; determining the total viscous damping coefficient of the high-rise building structure; the nominal damping coefficient of each viscous damping wall is determined; and a damper unit in the finite element model is continuously adjusted, so that the finite element model with the viscous damping wall meets the design requirement. According to the method, the vibration attenuation performance analysis and design efficiency of the viscous damping wall can be improved.

The invention discloses a floating fan damping control device and method based on a tuning multi-liquid-column damper. The system comprises a tuning multi-liquid-column damper installed on a floating platform, the tuning multi-liquid-column damper comprises a plurality of vertical liquid columns connected through a horizontal pipeline, and the horizontal pipeline is provided with a flow control valve and a controller. According to the method, the nonlinear water shake damping force of the TLMCD is equivalent to a linear damping term through a statistical linearization technology, and a linearization model suitable for modal analysis is established; key parameters of modal frequency and modal damping ratio are extracted, difference of dominant modal damping ratio is compared, and an influence mechanism of the modal damping ratio on vibration attenuation performance of the TLMCD is disclosed; and on the basis of the optimal damping parameter, continuous control is achieved by dynamically adjusting the head loss coefficient of the flow control valve. According to the method, the analysis and design problems of TLMCD nonlinear damping are solved, and the vibration suppression performance and the system robustness of the semi-submersible wind turbine under complex random wind wave excitation are improved.