Structural Dynamic Reliability on Supercavity Vehicle

2011 ◽  
Vol 230-232 ◽  
pp. 362-366
Author(s):  
Ming Liu ◽  
Wei Guang An
Keyword(s):  
Efficient Method ◽  
Random Excitation ◽  
Thin Shells ◽  
Good Precision ◽  
Structural Dynamic ◽  
Shell Elements ◽  
Dynamic Reliability ◽  
Wave Passage ◽  
Pseudo Excitation ◽  
Excitation Method

Dynamic reliability of supercavity vehicle is investigated. The vehicle is modeled as thin shells, using eight-node super-parametric shell elements. To deal with the tail of supercavity vehicle structures subjected to stationary random excitations, and the wave passage effect must be considered, an efficient method, the Pseudo Excitation Method, is suggested. The stationary random excitation is transformed into a deterministic transient excitation. The response can be obtained by Newark method, at last dynamic reliability of supercavity vehicle can be got base on the rule of first excursion failure. Examples show that this method is simple, efficient and has good precision.

Dynamic Reliability Evaluation by First-Order Reliability Method Integrated with Stochastic Pseudo Excitation Method

2020 ◽  
pp. 2150024
Author(s):  
Siyu Zhu ◽  
Tianyu Xiang
Keyword(s):  
Random Variable ◽  
Random Excitation ◽  
Pseudo Excitation Method ◽  
First Order Reliability Method ◽  
Dynamic Reliability ◽  
First Order ◽  
Reliability Method ◽  
Uncertain Structure ◽  
Pseudo Excitation ◽  
Excitation Method

The stochastic pseudo excitation method (SPEM), which is based on the principle of pseudo excitation method (PEM), is introduced to represent the randomness of dynamic input in which the amplitude of excitation is adopted as a random variable. Based on the mathematic definition of power spectral density, a physical interpolation of the SPEM is discussed. Even if one random variable is involved in calculation, the effects of the uncertainties are required to be investigated. The SPEM offers a simple but quite effective way to solve the dynamic reliability problem. Through integrating the new algorithm into first-order reliability method (FORM), the dynamic reliability of uncertain structure subjected to random excitation is studied. A linear oscillator with three types of white noise is adopted to verify the SPEM for dynamic reliability of linear random vibration analysis. Also, the accuracy and efficiency of SPEM to handle the multi-degree-of-freedom structure is investigated in this paper.

Dynamic Reliability of Stochastic Truss Structures under Random Load

2014 ◽  
Vol 525 ◽  
pp. 218-221
Author(s):  
Ming Liu ◽  
Hui Mei Zhang
Keyword(s):  
Structural Parameters ◽  
Random Excitation ◽  
Mean Value ◽  
Truss Structures ◽  
Physical Parameters ◽  
Random Load ◽  
Structural Dynamic ◽  
Dynamic Reliability ◽  
The Mean ◽  
Pseudo Excitation

Aim at the dynamic reliability of stochastic truss structures under stationary random excitation. In consideration of the randomness of structural physical parameters and the geometric parameters and the random excitations were first transformed into sinusoidal ones in terms of the pseudo excitation method ( PEM) , that turned the joint-random problem into a single random problem for which only structural parameters remain random, and thus the analysis is greatly simplified. The mean value and the variance of the mean square value of the structural displacement and velocity were computed by using the theory of spectral analysis. And then the expressions of stochastic truss structural dynamic reliability were educed from the Poisson formula. Finally, the influence of the randomness of structural parameters on the structural dynamic reliability was analyzed by an example; the method of this paper was proved feasible and available comparing with the Monte Carlo method.

An efficient method for non-stationary random vibration analysis of beams

2011 ◽  
Vol 17 (13) ◽  
pp. 2015-2022 ◽  
Author(s):  
Jie Yang ◽  
De-you Zhao ◽  
Ming Hong
Keyword(s):  
Efficient Method ◽  
Random Vibration ◽  
High Efficiency ◽  
Theoretical Method ◽  
Random Excitation ◽  
The Finite Element Method ◽  
Euler Beam ◽  
Time Step ◽  
Random Loads ◽  
Pseudo Excitation

An efficient method is presented to investigate the non-stationary random vibration response of structures. This method has the advantage of the accuracy of theoretical method in dealing with random loads and the versatility of the finite element method (FEM) in dealing with structures. In this paper, the Euler beam is adopted in the derivation of the governing equation. The uncoupled approach of the frequency-dependent system matrices is presented for solving the motion equation of forced vibration. The time-variance random dynamic response of the beam is analyzed by the precise integral method, meanwhile, the pseudo-excitation is applied to transform the non-stationary random excitation into deterministic pseudo one to simplify the solution of the dynamic equation. Solutions calculated by the FEM with different time step and theoretical analysis are also obtained for comparison. Numerical examples demonstrate the accuracy and high efficiency of the proposed method.

Random Characteristics of Vehicle-Bridge System Vibration by an Optimized Pseudo Excitation Method

2020 ◽  
Vol 20 (05) ◽  
pp. 2050069
Author(s):  
Siyu Zhu ◽  
Yongle Li
Keyword(s):  
Excitation Frequency ◽  
Time History ◽  
Harmonic Excitation ◽  
Random Excitation ◽  
Computational Effort ◽  
Cumulative Distribution ◽  
Pseudo Excitation Method ◽  
Rail Irregularities ◽  
Pseudo Excitation ◽  
Excitation Method

The pseudo excitation method (PEM) is improved for its efficiency by incorporating the self-adaptive Gauss integration (SGI) technology as a new combining integration. The PEM can transform the random rail irregularities into some pseudo harmonic excitation, which is a mature approach to deal with the random excitation for vehicle–bridge systems. The SGI was used to distinguish the significant from the insignificant parts of an integral section for the random excitation frequency on the stochastic response of the system, thereby reducing the computational effort required for the random vibration analysis of the system. Also, the SGI can intelligently handle the recognized integral section, by subdividing the important sections into several necessary frequency points, making rough decomposition, and allowing the unimportant regions to be eliminated. Based on selected frequency points, the deterministic pseudo harmonic excitations were generated, and then the standard deviation (SD) of the time history for the system was calculated by the PEM. The vehicle subsystem was simulated as a 23-degree of freedom model, and the bridge subsystem as a three-dimensional finite element model. The time-varying power spectral density (PSD) plots of the system were presented. Besides, the cumulative distribution function (CDF) of the response was calculated using Poisson’s crossing assumption. The random characteristics for the vehicle–bridge vibrations for different speeds and rail irregularities were calculated.

Effects of Intentional Large Mistuning to the Performance of B–B Friction Dampers in the Mistuned Bladed Disk Assembly Subjected to Narrow band Random Excitation

2021 ◽  
Author(s):  
Douksoon Cha
Keyword(s):  
Simple Model ◽  
Efficient Method ◽  
Narrow Band ◽  
Random Excitation ◽  
Additional Mass ◽  
Friction Dampers ◽  
Analytical Technique ◽  
Bladed Disk ◽  
Bladed Disk Assembly

Abstract In this study, the effects of intentional mistuning on the performance of B–B friction dampers are investigated in an inherently mistuned bladed disk assembly subjected to narrow band random excitation. The intentional large mistuning and inherent small mistuning are modeled by the additional mass and perturbations in the stiffness of the blade, respectively. It was found that the performance of B–B friction dampers improved owing to the intentional mistuning of the correlated excitations. Based on a simple model of an intentionally and inherently mistuned bladed disk assembly, the analytical technique offers an efficient method to evaluate the effects of intentional mistuning and friction dampers.

The SHEBA Family of Shell Elements for the Matrix Displacement Method

1968 ◽  
Vol 72 (694) ◽  
pp. 873-883 ◽  
Author(s):  
J. H. Argyris ◽  
D. W. Scharpf
Keyword(s):  
Boundary Layer ◽  
Thin Shells ◽  
Displacement Method ◽  
Considerable Effort ◽  
Shell Elements ◽  
The Past ◽  
The Matrix ◽  
Specific Geometry

Considerable effort has been extended over the past years in adapting the matrix displacement method to the specific problems of thin shells under membrane and bending action and developing suitable elements of varying sophistication. Some of the difficulties arising in the process of idealisation were reviewed in ref. 1. For example, simple considerations show that a representation of a shell by polyhedron surfaces may lead to serious errors, especially in the presence of pronounced bending and so-called boundary-layer effects. For this and other reasons it appears imperative to allow for the curvature of the shell. Much ingenuity has been shown in evolving elements for shells of specific geometry.

Simultaneous optimization of control parameters and placements of piezoelectric patches for active structural acoustic control of shell structures under random excitation

2020 ◽  
Vol 31 (9) ◽  
pp. 1204-1219
Author(s):  
Jingjuan Zhai ◽  
Linyuan Shang ◽  
Guozhong Zhao
Keyword(s):  
Simulated Annealing Algorithm ◽  
Simultaneous Optimization ◽  
Continuous Variables ◽  
Control Cost ◽  
Pseudo Excitation Method ◽  
Acoustic Control ◽  
Pseudo Excitation ◽  
Excitation Method ◽  
Element Method ◽  
Structural Acoustic Control

Simultaneous optimization of multiple parameters of an active structural acoustic control system under random force excitation is presented in this article. A method integrating the pseudo excitation method, finite element method, and boundary element method is proposed to analyze the random acoustic radiation. The active structural acoustic control of randomly vibrating structures is developed using the velocity feedback control scheme with the help of the pseudo excitation method. The acoustic design optimization model is proposed, in which the auto power spectral density of sound pressure is taken as the objective function and the placements of actuators/sensors as well as control gains are assigned as design variables. Taking into account the operational efficiency and control cost, the number of actuators/sensors and the total actuation energy are considered as constraints. A simulated annealing algorithm is employed for the optimization problem with discrete and continuous variables coexisting. Numerical examples are given to demonstrate the effectiveness of the proposed methods and the programs, and several key factors on the optimized designs are also discussed.

Random Vibration Analysis for Centrifugal Compressor Impellers With Unsteady Aerodynamic Excitations

2016 ◽  
Author(s):  
Yuefang Wang ◽  
Yan Liu ◽  
Xuejun Wang ◽  
Hongkun Li ◽  
Daren Jiang
Keyword(s):  
Spectral Density ◽  
Power Spectral Density ◽  
Centrifugal Compressor ◽  
Random Vibration ◽  
Pressure Field ◽  
Pseudo Excitation Method ◽  
Vibration Problem ◽  
Power Spectral ◽  
Pseudo Excitation ◽  
Excitation Method

Dynamic response of impeller of centrifugal compressor is studied considering pulsating pressure field on blades due to unsteady flow conditions. The aerodynamic forces on the blades are modeled as random load whose spectral characteristics are determined through computational fluid dynamic simulations in the time domain. The dynamical response in the unsteady case is solved as a random vibration problem in the frequency domain which provides useful power spectral density displacement and stress for early stage of impeller design. A semi-open impeller mounted with 19 blades is modeled using three dimensional solid finite elements. The random vibration problem of the impeller is solved through the Pseudo-Excitation Method considering spatial variance of the pressure field. A user-defined module is developed based on harmonic analysis to generate the auto power spectral density and variance of displacement and stress at 200 nodes. It is demonstrated that solving a random vibration problem through the Pseudo-Excitation Method is faster than the commonly adopted multiple-step transient analysis. It is concluded that evaluating the structural integrity of impeller solids in the regime of random vibration is a feasible and efficient approach at the early design stage of compressors.

Sign in / Sign up

Export Citation Format

Share Document