A Global Sensitivity Approach for the Dynamic Response of Printed Wiring Boards

1995 ◽  
Vol 117 (1) ◽  
pp. 7-13 ◽  
Author(s):  
H. Jensen ◽  
A. O. Cifuentes
Keyword(s):  
Dynamic Response ◽  
Probabilistic Approach ◽  
Printed Wiring Boards ◽  
Global Sensitivity ◽  
Probabilistic Distribution ◽  
Design Variables ◽  
Sensitivity Approach ◽  
General Method

This paper is concerned with the sensitivity of the dynamic response of printed wiring boards (PWB). A general method to study the sensitivity of the response of the board as a function of the variability of the design variables is presented. The method, which is based on a probabilistic approach, assumes that the design variables belong to a given interval and follow a known probabilistic distribution.

The Dynamic Response and Sensitivity Analysis of the SFD-Sliding Bearing Flexible Rotor System

2012 ◽  
Vol 472-475 ◽  
pp. 1460-1464
Author(s):  
Ji Yan Wang ◽  
Yu Cheng Zhao ◽  
Chao Wang
Keyword(s):  
Dynamic Response ◽  
Periodic Motion ◽  
Period Doubling ◽  
Rotor System ◽  
Flexible Rotor ◽  
Sliding Bearing ◽  
Runge Kutta Method ◽  
Design Variables ◽  
Design Cycle ◽  
Stable Periodic

The paper established the mechanical model of SFD-sliding bearing flexible rotor system, adopting Runge-Kutta method to solve nonlinear differential equation, thus acquiring the dynamic response and the unbalanced response curve. The study has shown: from stable periodic motion, the route of the flexible rotor system to go into chaos is: periodic motion—quasi-periodic motion—chaos—period doubling bifurcation—chaos. The paper analyzed the sensitivity of the first two critical speeds of flexible rotor system, offering design variables for optimization analysis, improving the efficiency of optimization and shortening the design cycle.

Sensitivity of the Human Comfort Equation and of Free Convection in a Vertical Enclosure as Examples of the Use of Global Sensitivity to Evaluate Parameter Interactions

2009 ◽  
Vol 132 (1) ◽  
Author(s):  
A. F. Emery ◽  
M.-H. H. Wu ◽  
A. M. Mescher
Keyword(s):  
Free Convection ◽  
Human Comfort ◽  
Global Sensitivity ◽  
Sensitivity Studies ◽  
Multiple Variables ◽  
Sensitivity Approach ◽  
Parameter Interactions ◽  
Scientific Systems ◽  
Large Interaction

Many models of engineering and scientific systems involve interactions between and among the parameters, stimuli, and physical properties. The determination of the adequacy of models for predictions and for designing experiments generally involves sensitivity studies. Good designs mandate that the experiments be sensitive to the parameters sought with little interaction between them because such interaction generally confuses the estimation and reduces the precision of the estimates. For design purposes, analysts frequently want to evaluate the sensitivities of the predicted responses to specific variables, but if the variables interact it is often difficult to separate the effects. Global sensitivity is a technique by which one can evaluate the magnitude of the interactions between multiple variables. In this paper, the global sensitivity approach is applied to the human comfort equation and to free convection in a rectangular enclosure. It is found that when occupants are uncomfortable, there is little interaction and that one can predict the effects of changing several environmental conditions at once by adding the separate effects. But when occupants are comfortable, there is a large interaction and the effects cannot be treated separately. Free convective heat transfer in an enclosure is a function of the Rayleigh number Ra and the aspect ratio H/W, and the flow field changes from unicellular to multicellular as Ra increases. There is a strong interaction for H/W≤2 but little for H/W≥2.

Global Sensitivity Analysis for Stay Vane and Casing Design of Reaction Hydraulic Turbine

2019 ◽  
Author(s):  
Hyunkyoo Cho ◽  
Ujjwal Shrestha ◽  
Young-Do Choi ◽  
Jungwan Park
Keyword(s):  
Sensitivity Analysis ◽  
Design Process ◽  
Performance Measures ◽  
Global Sensitivity Analysis ◽  
Computational Cost ◽  
Surrogate Models ◽  
Sensitivity Index ◽  
Global Sensitivity ◽  
Design Variables ◽  
Hydraulic Turbines

Abstract Global sensitivity analysis (GSA) estimates influence of design variables in the entire design domain on performance measures. Hence, using GSA, important design variables could be found for an engineering application with high dimension which require computationally expensive analyses. Then, similar engineering applications could use selected variables to carry out design process with smaller dimension and affordable computational cost. In this study, GSA has been carried out for the performance measures in design of stay vane and casing of reaction hydraulic turbines. Global sensitivity index method is used for GSA because it can fully capture the effect of interaction between the design variables. For efficiency, genetic aggregation surrogate models are constructed using the responses of computational fluid dynamic (CFD) analysis. Global sensitivity indices for the performance measures of stay vane and casing have been evaluated using the surrogate models. It is found that less than three design variables among 12 are effective in the design process of stay vane and casing in reaction hydraulic turbines.

Evaluation of the Lateral Vibration Response of Footbridges under Uncertainty Conditions

2022 ◽  
Author(s):  
Rocío García-Cuevas ◽  
Javier F. Jiménez-Alonso ◽  
Carlos Renedo M.C. ◽  
Francisco Martinez
Keyword(s):  
Distribution Function ◽  
Natural Frequency ◽  
Damping Ratio ◽  
Probabilistic Approach ◽  
Structural Response ◽  
Modal Parameters ◽  
Critical Number ◽  
Lateral Instability ◽  
Lateral Vibrations ◽  
Probabilistic Distribution

<p>The evaluation of the vibration performance of footbridges due to walking pedestrians is an issue of increasing importance in current footbridge design practice. The growing trend of slender footbridges with long spans and light materials has led to serviceability problems in lateral vibrations, which occur when the number of pedestrians reaches a “critical number”. Considering the mode of vibration in which the lateral instability is more likely to develop, the structural response depends on the modal characteristics of the footbridge; in particular, the natural frequency and the damping ratio. These modal parameters are stochastic variables, as it is not possible to determine them without a level of uncertainty. Thus, the purpose of this paper is to obtain the value of the lateral dynamic response of slender footbridges with a certain confidence level under uncertainty conditions. The uncertainties of those modal parameters are considered using a probabilistic approach. Both the natural frequency and the damping ratio are modelled as uncorrelated random variables that follow a predetermined probabilistic distribution function. Consequently, the structural response will also be described by a probabilistic distribution function, which can be estimated through Monte Carlo numerical simulations. As a result, the study allows the footbridge lateral response and the critical number of pedestrians to be calculated for different confidence levels and load scenarios, especially for crowd densities above the “critical number”.</p>

scholarly journals Method for the multi-criteria optimization of car wheel suspension mechanisms

2016 ◽  
Vol 36 (2) ◽  
pp. 60 ◽  
Author(s):  
Catalin Alexandru ◽  
Vlad Totu
Keyword(s):  
Computer Program ◽  
Kinematic Synthesis ◽  
Axis Direction ◽  
Car Body ◽  
Race Car ◽  
Design Variables ◽  
Kinematic Behavior ◽  
Kinematic Study ◽  
Kinematic Position ◽  
General Method

The paper deals with a general method for the multi-criteria optimization of the rear wheels suspension mechanisms in terms of kinematic behavior. The suspension mechanism is decomposed in basic binary links, and the kinematic synthesis is separately performed for each of them. The design variables are the global coordinates of the joint locations on the car body (chassis). The disposing of the joints on the wheel carrier were exclusively established by constructive criteria. The design objectives relate to kinematic position parameters of the wheel (displacements of the wheel centre along longitudinal and transversal directions, and modifications of the wheel axis direction), the optimization goal being to minimize these variations during the wheel travel. A computer program for the kinematic study was developed in C++. The application was performed for the wheel suspension mechanism of a race car.

scholarly journals Remarks on optimization of impact damping for a non-ideal and nonlinear structural system

2020 ◽  
pp. 146134842094007
Author(s):  
Marcelo A Silva ◽  
Alexandre M Wahrhaftig ◽  
Reyolando MLRF Brasil
Keyword(s):  
Dynamic Response ◽  
Optimization Problems ◽  
Augmented Lagrangian Method ◽  
Equations Of Motion ◽  
Maximum Amplitude ◽  
Power Source ◽  
Structural System ◽  
Impact Damper ◽  
Design Variables ◽  
The Impact

It is intended, in this work, to present some research results on the optimization of an impact damper for a structural system excited by a non-ideal power source. In the model, the impact vibration absorber is, basically, a small free mass inside a box carved in the structure that undergoes undamped linear motions colliding against the walls of the box. Whenever the mass shocks against the walls of the box, an exchange of kinetic energy between the mass and the structure may be used to control the amplitude of the dynamic response of the structure. In this work, the structure is excited by a non-ideal power source, a DC electric motor installed on it, which may present the Sommerfeld effect. A non-ideal power source is one that interacts with the motion of the structure as opposed to an ideal source whose amplitude and frequency are fixed, independent of the displacements of the structure. Here, the dynamic response of the system is computed using step-by-step numerical integration of the equations of motion derived via a Lagrangian formulation. The optimization problem is defined considering as the objective function the maximum amplitude of the structure displacement, while the design variables are the weight of the free mass and the width of the carved box. Using the augmented Lagrangian method, several optimization problems are formulated, and, solving them, the best design to maximize the efficiency of the impact damper is obtained.

Sensitivity of the Human Comfort Equation: An Example of the Use of Global Sensitivity to Evaluate Sensitivity Interactions

2007 ◽  
Author(s):  
A. F. Emery ◽  
MingHang H. Wu
Keyword(s):  
Physical Properties ◽  
Environmental Conditions ◽  
Human Comfort ◽  
Global Sensitivity ◽  
Sensitivity Studies ◽  
Multiple Variables ◽  
Sensitivity Approach ◽  
Scientific Systems ◽  
Large Interaction

Many models of engineering and scientific systems involve interactions between and among the parameters, stimuli, and physical properties. The determination of the adequacy of models for predictions and for designing experiments generally involves sensitivity studies. This is particularly true for experiments by which properties are to be estimated. Good designs mandate that the experiments be sensitive to the parameters sought with little interaction between them because such interaction generally confuse the estimation and reduce the precision of the estimates. For design purposes, analysts frequently want to evaluate the sensitivities of the predicted responses to specific variables but it the variables interact it is often difficult to separate the effects. Global sensitivity is a technique by which one can evaluate the magnitude of the interactions between multiple variables. In this paper the global sensitivity approach is applied to the human comfort equation. The aim is twofold: 1) to demonstrate the usefulness of the global sensitivity approach, 2) to increase our understanding of how human comfort is affected by activity, clothing, and environmental conditions. It is found that when occupants are uncomfortable there is little interaction and that one can predict the effects of changing several environmental conditions at once by adding the separate effects. But when occupants are comfortable there is a large interaction and the effects cannot be treated separately.

scholarly journals Evaluation of capabilities of different global sensitivity analysis techniques for building energy simulation: experiment on design variables

2021 ◽  
Vol 21 (2) ◽  
pp. 89-111
Author(s):  
Arthur Santos Silva ◽  
Enedir Ghisi
Keyword(s):  
Sensitivity Analysis ◽  
Global Sensitivity Analysis ◽  
Computational Cost ◽  
Building Performance ◽  
Commercial Building ◽  
Building Performance Simulation ◽  
Global Sensitivity ◽  
Heating And Cooling ◽  
Design Variables ◽  
Cooling Loads

Abstract The objective of this study is to investigate the capabilities of different global sensitivity analysis methods applied to building performance simulation, i.e. Morris, Monte Carlo, Design of Experiments, and Sobol methods. A single-zone commercial building located in Florianópolis, southern Brazil, was used as a case study. Fifteen inputs related to design variables were considered, such as thermal properties of the construction envelope, solar orientation, and fenestration characteristics. The performance measures were the annual heating and cooling loads. It was found that each method can provide different visual capabilities and measures of interpretation, but, in general, there was little difference in showing the most influent and least influent variables. For the heating loads, the thermal transmittances were the most influent variables, while for the cooling loads, the solar absorptances stood out. The Morris method showed to be the most feasible method due to its simplicity and low computational cost. However, as the building simulation model is still complex and non-linear, the variance-based method such as the Sobol is still necessary for general purposes.

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