A Survey of Nonlinear Analysis Tools for Structural Systems

1998 ◽  
Vol 30 (5) ◽  
pp. 363-369 ◽  
Author(s):  
M. Imregun
Keyword(s):  
Nonlinear Analysis ◽  
Structural Systems ◽  
Analysis Tools

scholarly journals Development of nonlinear analysis tools on FPGA

2017 ◽  
Vol 8 (2) ◽  
pp. 173-179
Author(s):  
Shogo Shimada ◽  
Hiroyuki Kitajima
Keyword(s):  
Nonlinear Analysis ◽  
Analysis Tools

Analysis and Control of Nonlinear Systems

1993 ◽  
Vol 115 (2B) ◽  
pp. 351-361 ◽  
Author(s):  
J. Karl Hedrick
Keyword(s):  
Nonlinear Analysis ◽  
Flight Control ◽  
Model Error ◽  
Forced Response ◽  
Equivalent Linearization ◽  
Statistical Linearization ◽  
Linearization Methods ◽  
Analysis Tools ◽  
Highly Nonlinear ◽  
And Control

This paper describes my work on nonlinear analysis and control over the last twenty years. The first part of the paper concerns the development of nonlinear analysis tools for predicting stability and forced response characteristics of high speed ground vehicles. The principal motivation was to develop an alternative to “brute force” time domain simulation. The developed tools were extensions of “describing function” or “equivalent linearization” methods for both periodic and stochastic excitation. The “statistical linearization” analysis tools were then extended and applied to design control laws for nonlinear stochastic regulators. The second part of the paper was motivated by control system design for highly nonlinear, multivariable systems, such as automotive powertrain control and aircraft flight control. For these classes of systems, statistical linearization procedures are computationally cumbersome and also provide no stability or robustness guarantees. A method which has proven extremely powerful, both theoretically and experimentally, is “sliding control.” This technique is a form of input/output linearization that directly incorporates model error information with stability and performance measures. My students and I found several difficulties in the direct application of this method to automotive and aircraft control. This paper describes our solutions to the problems of repeated model differentiation, differentiation of model error, undesirable “internal dynamics” and systems with saturating control inputs.

scholarly journals A Novel Megastable Hamiltonian System with Infinite Hyperbolic and Nonhyperbolic Equilibria

Complexity ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Gervais Dolvis Leutcho ◽  
Theophile Fonzin Fozin ◽  
Alexis Nguomkam Negou ◽  
Zeric Tabekoueng Njitacke ◽  
Viet-Thanh Pham ◽  
...  
Keyword(s):  
Hamiltonian System ◽  
Nonlinear Analysis ◽  
Chaotic Systems ◽  
Engineering Application ◽  
Ergodic Property ◽  
Dissipative Systems ◽  
Conservative Oscillator ◽  
Analysis Tools ◽  
The Stability ◽  
New System

The dimension of the conservative chaotic systems is an integer and equals the system dimension, which brings about a better ergodic property and thus have potentials in engineering application than the dissipative systems. This paper investigates the phenomenon of megastability in a unique and simple conservative oscillator with infinite of hyperbolic and nonhyperbolic equilibria. Using traditional nonlinear analysis tools, we found that the introduced oscillator possesses an invariable energy and displays either self-excited or hidden dynamics depending on the stability of its equilibria. Besides, the conservative nature of the new system is validated using theoretical measurement. Furthermore, an analog simulator of the oscillator is built and simulated in the PSpice environment to confirm that the previous results were not artifacts.

scholarly journals Numerical Simulation of the Semi-Rigid Behaviour of Integrally Attached Timber Folded Surface Structures

Buildings ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 55 ◽  
Author(s):  
Andrea Stitic ◽  
Anh Nguyen ◽  
Aryan Rezaei Rad ◽  
Yves Weinand
Keyword(s):  
Nonlinear Analysis ◽  
Large Scale ◽  
Numerical Models ◽  
Element Model ◽  
Surface Structures ◽  
Structural Systems ◽  
Structural Behaviour ◽  
Fe Modelling ◽  
Spring Element ◽  
Modeling Strategy

Timber folded surface structures assembled using semi-rigid multiple tab and slot joints (MTSJ) have been shown to form feasible structural systems with high load bearing potential. However, for their further development and use on large building scales, a pertinent model for prediction of their structural behaviour has yet to be developed. This paper focuses on simplified numerical methods for accurately modelling the semi-rigid structural behaviour of bidirectional timber folded surface structures with multiple tab and slot connections. Within this scope, the structure behaviour is considered to be in the elastic stage. Three practical methods of analysis for such structural systems are presented. The first two approaches use the Finite Element Method (FEM), where the theory of plates and shells are applied. In the first method, the MTSJs are modeled using strip element models, while, in the second strategy, spring models are used. The third modeling strategy elaborates on the new macroscopic mechanical models, referred to as macro models. Sets of one-dimensional (1D) elements are used to represent the mechanical behaviour of the entire system. Both linear and geometric nonlinear analysis are performed for all three modeling strategies. The numerical results are then validated against the large scale experiments. Comparison of the strip and spring element model results have shown that the strips represent more accurately the experimentally obtained values. Concerning the macro modelling approach, very good agreement with both detailed FE modelling approaches, as well as experimental results, were obtained. The results indicate that both linear and nonlinear analysis can be used for modelling the displacements within the elastic range. However, it is essential to include geometric nonlinearities in the analysis for accurate modelling of occurring strains as well as for displacements when considering higher load levels. Finally, it is demonstrated that including semi-rigidity in the numerical models is of high importance for analysing the behaviour of timber folded surface structures with MTSJ.

Reflections on Nonlinear Dynamics of Machines and Structures

2000 ◽  
Vol 16 (2) ◽  
pp. 79-83
Author(s):  
Francis C. Moon
Keyword(s):  
Nonlinear Dynamics ◽  
Nonlinear Analysis ◽  
Relative Motion ◽  
Short Note ◽  
Structural Systems ◽  
Machine Systems ◽  
Multi Body

ABSTRACTIn this short note a comparison is made between the methodology of nonlinear analysis in machine systems versus structural systems. Because of strong nonlinearities in machines with parts in relative motion, chaotic-like dynamics are more likely to occur in complex multi-body machines than in structural systems. Furthermore, it is conjectured that well designed machines have evolved to where a small amount of chaos is always present and is sometimes desired.

scholarly journals Comparison of nonlinear solution techniques named arc-length for the geometrically nonlinear analysis of structural systems

2021 ◽  
Vol 9 (3B) ◽  
Author(s):  
TALASLIOĞLU Tuğrul ◽  
Keyword(s):  
Nonlinear Analysis ◽  
Geometric Nonlinearity ◽  
Nonlinear Behavior ◽  
Structural Systems ◽  
Geometrically Nonlinear ◽  
Arc Length ◽  
Structural System ◽  
Geometrically Nonlinear Analysis ◽  
Benchmark Tests ◽  
Nonlinear Responses

The nonlinearity issue is one of the promising fields in the engineering area. Particularly, the geometric nonlinearity bears big importance for the structural systems showing a tendency of larger deflection. In order to obtain a correct load-deflection relation for the structural system subjected to any external load, an advanced incremental-iterative based approach has to be utilized in the analysis of nonlinear responses. Arc length method has been proven to be the most perfect one among the nonlinear analysis approaches. Thus, it is extensively applied to the structural systems with pin-connected joints. This study attempts to compare two variations of arc length method named “spherical” and “linearized” for the nonlinear analysis of structural system with rigid-connected joints. Also, two different element formulations are utilized to discretize the structural systems. Two open-source coded programs, Opensees and FEAP, are employed for six benchmark structural systems in order to compare the performance of employed arc-length techniques. Furthermore, in order to make a further observation in the nonlinear behavior of application examples, their simulations are not only sketched using graphs, but also displayed through the movies for each of benchmark tests. Consequently, the linearized type arc length technique implemented in FEAP shows a more success with a better prediction of load-deflection relation, noting that Opensees has a big advantage of having an element, which is capable of simulating the geometric nonlinearity.

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