The dynamical response analysis of piezoelectric flexible structures based on model reduction

2008 ◽  
Author(s):  
Jingjun Zhang ◽  
Lili He ◽  
Ruizhen Gao
Keyword(s):  
Model Reduction ◽  
Flexible Structures ◽  
Response Analysis ◽  
Dynamical Response

A statistical study on artificially generated earthquake records

1976 ◽  
Vol 3 (1) ◽  
pp. 11-19
Author(s):  
W. K. Tso ◽  
B. P. Guru
Keyword(s):  
Statistical Study ◽  
Spectral Response ◽  
Flexible Structures ◽  
Time History ◽  
Maximum Response ◽  
Response Analysis ◽  
Seismic Region ◽  
Natural Period ◽  
Earthquake Records ◽  
Time History Response

A statistical study has been done to investigate (i) the variation of spectral responses of structures due to artificially generated earthquake records with identical statistical properties, (ii) the effect of duration of strong shaking phase of artificial earthquakes on the response of structures, and (iii) the number of earthquake records needed for time-history response analysis of a structure in a seismic region. The results indicate that the flexible structures are more sensitive to the inherent statistical variations among statistically identical earthquake records. Consequently several records must be used for time-history response analysis. A sample of eight or more records appear to provide a good estimate of mean maximum response. The duration of strong shaking can significantly affect the maximum response. Based on the results, it is suggested that for the purpose of estimating peak response, the strong shaking duration of the input earthquake motion should be at least four times the natural period of the structure. The maximum responses due to statistically identical ground motion records are observed to fit approximately the type 1 extreme value distribution. Thus, it is rationally possible to choose a design value based on the mean, standard deviation of the spectral response values and tolerable probability of exceedance.

Sensitivity Analysis for Dynamical Response of Reactor Coolant System Based on OPTIMUS

2020 ◽  
Author(s):  
Yuan Yanli ◽  
Ye Xianhui ◽  
Li Lijuan ◽  
Yuan Feng
Keyword(s):  
Sensitivity Analysis ◽  
Steam Generator ◽  
Nuclear Power ◽  
Reactor System ◽  
Response Analysis ◽  
Dynamical Response ◽  
Calculation Error ◽  
Reactor Coolant ◽  
Input Parameters ◽  
Coolant System

Abstract The sensitivity analysis of the dynamical response of reactor coolant system to the input parameters is an important precondition for the design optimization. In this paper, the sensitivity of the dynamical loads at the nozzles of the equipment under seismic conditions is analyzed with an integrated platform called OPTIMUS, taking the stiffness of the dampers in the steam generator and the main pump as the input variables. The key parameters of the reactor system are usually different from the design value due to the calculation error, random and other uncontrollable errors in the manufacturing process and installation process. In a nuclear power project, the measured stiffness values of the dampers on the steam generator and the main pump in the manufacturer are deviated from the requirements in the equipment specification, and it is necessary to evaluate the influence of the deviation on the dynamical response analysis of the reactor system. According to the traditional method, it is necessary to establish the models of the reactor coolant system for nonlinear analysis according to the different stiffness of the dampers, and then the calculation results are compared by EXCEL. In this paper, the sensitivity analysis of output parameters which are the loads at the nozzles of the equipment to the input parameters which are the stiffness of the dampers on the steam generator and pump is realized by OPTIMUS, which is a kind of integration platform. Not only can ANSYS simulation calculations be carried out automatically on the OPTIMUS, but also the output data can be processed rapidly automatically, and the influence of manufacturing deviation of the stiffness of the dampers on the dynamical response of the reactor coolant system can be analyzed quantitatively in the above-mentioned problems, and the data support is provided for the determination of the design variables for subsequent optimization analysis.

Research on Influence of the Bank Slope on the Acceleration Distribution of the Central Points of Concrete-Faced Rockfill Dam

2012 ◽  
Vol 568 ◽  
pp. 242-247
Author(s):  
Hui Zhou ◽  
Ping Hu ◽  
Ren Cheng Xiao
Keyword(s):  
Seismic Intensity ◽  
River Valley ◽  
Response Analysis ◽  
Dynamical Response ◽  
Maximum Acceleration ◽  
Systematic Analysis ◽  
Horizontal Acceleration ◽  
Bank Slope ◽  
Rockfill Dam ◽  
High Dams

3-D dynamical response analysis of concrete-faced rockfill dam is presented. Using equivalent-linear model, based on different dam heights and different shapes of river valley, the responses of dam subjected to different seismic intensity inputs have been studied. Especially the systematic analysis about the influence of the bank slope on the distribution of the acceleration at the central points the bank slope is conducted. The results show that, the distribution of the horizontal acceleration along the dam heights at the central points on the central section of concrete-faced rockfill dam performs that the acceleration magnification which increases remarkably over 0.8H is a little smaller during 0~0.8H. For high concrete-faced rockfill dam, with the base acceleration excitations unchanged and the bank slope becoming gentle, the maximum acceleration on the top of the dam reduces. Under various seismic intensities, for non-high dams in the broad river valley the slope has almost no impact on the magnification of the horizontal acceleration.

scholarly journals Approximate Inertial Manifold-Based Model Reduction and Vibration Suppression for Rigid-Flexible Mechanical Arms

Complexity ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Lisha Xu ◽  
Hua Deng ◽  
Chong Lin ◽  
Yi Zhang
Keyword(s):  
Model Reduction ◽  
Dynamic Model ◽  
Input Signal ◽  
Angular Displacement ◽  
Target Position ◽  
Response Analysis ◽  
Inertial Manifold ◽  
Residual Vibration ◽  
Approximate Inertial Manifold ◽  
Simulation Results

The dynamic characteristics of the mechanical arm with a rigid-flexible structure are very complex. The reason is that it is a complex DPS (distributed parameter system) with infinite dimension and nonlinearity in essence due to the rigid-flexible coupling. So, accurately positioning and controlling the rigid-flexible mechanical arms could be difficult. Therefore, a model reduction method of rigid-flexible mechanical arms based on the approximate inertial manifold is put forward. To repress the residual vibration of the end of the mechanical arm, a feedforward control strategy is designed. The high-dimensional solution of the vibration equation of the rigid-flexible mechanical arms is projected into the complete space composed of orthogonal decomposition modes. By using Galerkin’s method, the system is simplified and the approximate solution is obtained through the interaction between high-order and low-order modes. The truncated finite mode is also used to construct a lowest-order dynamic model on the basis of approximate inertia manifold. Given the reduced-order rigid-flexible mechanical arms dynamic model, dynamic response analysis is conducted to optimize the target position error and end residual vibration. A limited number of sinusoidal signals approximately combine the input signal, by using the particle swarm optimization algorithm to optimize the input signal, and the amplitude of the sinusoidal signal is corrected. The simulation results depict the superiority of the proposed method, which greatly suppresses the end residual vibration of the mechanical arm and realizes the accurate positioning of the end of the mechanical arm. In addition, the hardware experimental device of the rigid-flexible mechanical arms is constructed, and the experimental verification of the above method is put into effect. The simulation results of angular displacement and end vibration of the reduced model are accordant which is shown by the experimental results of the hardware platform.

Design Seastates for Extreme Response of Jackup Structures

1998 ◽  
Vol 120 (2) ◽  
pp. 103-108 ◽  
Author(s):  
S. R. Winterstein ◽  
R. Torhaug ◽  
S. Kumar
Keyword(s):  
Earthquake Engineering ◽  
Time Domain ◽  
Flexible Structures ◽  
Wave Model ◽  
Response Prediction ◽  
Wave Crest ◽  
Response Analysis ◽  
New Wave ◽  
Extreme Response ◽  
Wave Methods

The extreme response of a jackup structure is studied. We consider how design seastate histories can be introduced to reduce the cost of time-domain response analysis. We first identify critical wave characteristics for extreme response prediction. In quasi-static cases, the maximum wave crest height, ηmax, is shown to best explain extreme deck sway. For more flexible structures we introduce a new wave characteristic, SD, based on response spectral concepts from earthquake engineering. Finally, we show how accurate response estimates can require fewer time-domain analyses, provided design seastates are pre-selected to ensure that ηmax or SD is near its average value. With respect to standard Monte-Carlo simulation, these design seastates achieve at least a 50-percent reduction in response variability, and hence at least a fourfold savings in needed simulation cost. These results may lend insight, not only into time-domain simulation, but also into more fundamental questions of jackup behavior. They also suggest that, at least in quasi-static cases, still simpler design wave methods based on ηmax may suffice. We illustrate and evaluate some such design wave methods here (e.g., the “new wave” model and others based on Slepian theory).

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