A Two-Step Methodology for the Generation of Accurate Finite Element Models of Nonlinear Mechanical Systems

2004 ◽  
Author(s):  
Gae¨tan Kerschen ◽  
Jean-Claude Golinval
Keyword(s):  
Model Updating ◽  
Nonlinear Models ◽  
The Other ◽  
Finite Element Models ◽  
Numerical Application ◽  
Nonlinear Parameters ◽  
Nonlinear Mechanical ◽  
Computational Structural Mechanics ◽  
Linear And Nonlinear ◽  
Nonlinear Mechanical Systems

Model updating and validation is currently a central issue in the fields of computational structural mechanics and dynamics. The vast majority of applications however concerns linear structures. On the other hand, updating nonlinear models is something the structural dynamicist prefers to avoid mainly because tools such as modal analysis are no longer available. The objective of the present study is to propose a two-step methodology for dealing with nonlinear systems. Its most appealing feature is that it decouples the estimation of the linear and nonlinear parameters. A numerical application consisting of an aeroplane-like structure is used to assess the efficiency of the procedure.

scholarly journals An Optimal Estimation Method for Nonlinear Models of Mechanical Systems

1994 ◽  
Vol 116 (4) ◽  
pp. 805-810 ◽  
Author(s):  
M. J. G. van de Molengraft ◽  
F. E. Veldpaus ◽  
J. J. Kok
Keyword(s):  
Nonlinear Models ◽  
A Priori ◽  
Mechanical Systems ◽  
Estimation Method ◽  
Optimal Estimation ◽  
Model Structure ◽  
Unknown Parameters ◽  
Starting Point ◽  
Nonlinear Mechanical ◽  
Nonlinear Mechanical Systems

This paper presents an optimal estimation method for nonlinear mechanical systems. The a priori knowledge of the system in the form of a nonlinear model structure is taken as a starting point. The method determines estimates of the parameters and estimates of the positions, velocities, accelerations, and inputs of the system. The optimal estimation method is applied to an experimental mechanical system. The unknown parameters in this system relate to inertia, friction and elastic deformation. It is shown that the optimal estimation method on the basis of a relatively simple model structure can lead to a useful description of the system.

scholarly journals Mathematical Modeling for Prediction of Heating and Air-Conditioning Energies of Multistory Buildings in Duhok City

2018 ◽  
Vol 7 (4) ◽  
pp. 153
Author(s):  
Neven E. Zaya ◽  
Lokman H. Hassan ◽  
Halis Bilgil
Keyword(s):  
Air Conditioning ◽  
Perfect Matching ◽  
Nonlinear Models ◽  
The Other ◽  
Multistory Buildings ◽  
The Third ◽  
The Common ◽  
Linear And Nonlinear ◽  
Predicted Values ◽  
Building Walls

Present endeavor is devoted to estimate the air-conditioning and heating energies or loads of modern buildings in Duhok City, Iraq using new mathematical models. Many parameters have been considered in current modeling, namely, area of building, number of storeys and types of the common materials of the building walls. Regression analysis is performed to formulate new mathematical linear and nonlinear models for the loads. In addition, Fuzzy logic is utilized in the third model employing Sugeno's regulation. The outcomes reveal that the reasonable matching is achieved between the proposed models and mechanical engineering analytical solutions of heating and air-conditioning standards. Consequently, high correlation coefficient as more than 85% is determined between the predicted values of the models and analytical results. The linear model shows perfect matching with the analytical outputs more than the other proposed mathematical formulations.

Modeling Flutter Using Deflection-Dependent Strain-Rate Damping

2010 ◽  
Author(s):  
Soroush Norouzi ◽  
Siamak Arzanpour
Keyword(s):  
Strain Rate ◽  
Linear Models ◽  
Nonlinear Models ◽  
The Other ◽  
Large Deflections ◽  
Critical Importance ◽  
Nonlinear Simulation ◽  
The Past ◽  
Dependent Strain ◽  
Linear And Nonlinear

Flutter is a flow-induced unstable motion in structures that has drawn researchers’ attention in the past decades due to its presence in numerous applications including aviation. Linear and nonlinear models of flutter have been developed. Linear models are simple and accurate for predicting the critical velocity at which flutter occurs. However, they are not capable of describing the post-flutter behavior of structures. Nonlinear models, on the other hand, can properly demonstrate the unstable motion accompanied with the occurrence of flutter but they are highly complicated. In fact, numerical solution of these equations requires extensive computations. As a result, having a model that is both simple and valid for post-flutter simulations is of critical importance. Linear models lose their accuracy when large deflections take place in the structure. This is when the unconsidered tensions that oppose large deflections come into play and render the behavior of the structure nonlinear. Usually, a type of damping relative to strain-rate is assumed for modeling structures under flutter. This paper introduces a deflection-dependant strain-rate damping coefficient to the linear flutter model, so as the deflections grow the restraining forces increase to limit the motion. The new sets of equations are derived and simulations are conducted to ensure the capability of the model to capture the post-flutter behavior. Results are then compared with the results of nonlinear simulation to demonstrate the new model’s compliance with those of nonlinearly-modeled systems.

scholarly journals Application of physical function model to state estimations of nonlinear mechanical systems

IEEE Access ◽  
2021 ◽  
pp. 1-1
Author(s):  
Heisei Yonezawa ◽  
Itsuro Kajiwara ◽  
Shota Sato ◽  
Chiaki Nishidome ◽  
Takashi Hatano ◽  
...  
Keyword(s):  
Physical Function ◽  
Mechanical Systems ◽  
Function Model ◽  
Nonlinear Mechanical ◽  
State Estimations ◽  
Nonlinear Mechanical Systems

Comparison of linear and nonlinear models to estimate body weight of Pelibuey ewes from body measurements

2021 ◽  
Vol 53 (1) ◽  
Author(s):  
Rafael Macedo-Barragán ◽  
Victalina Arredondo-Ruiz ◽  
Carlos Haubi-Segura ◽  
Paola Castillo-Zamora
Keyword(s):  
Body Weight ◽  
Nonlinear Models ◽  
Body Measurements ◽  
Linear And Nonlinear
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