Nonlinear Dynamic Analysis of an Icosahedron Frame which Exhibits Chaotic Behavior

2016 ◽  
Vol 12 (1) ◽  
Author(s):  
Lucas W. Just ◽  
Anthony M. DeLuca ◽  
Anthony N. Palazotto
Keyword(s):  
Dynamic Response ◽  
Boundary Conditions ◽  
Dynamic Analysis ◽  
Chaotic Behavior ◽  
Research Question ◽  
Nonlinear Dynamic Analysis ◽  
Surface Force ◽  
Element Analysis ◽  
Point Distribution ◽  
Chaotic Response

The research question addressed is whether a lighter than air vehicle (LTAV), which uses an internal vacuum to become positively buoyant, can be designed to provide extended loiter for U.S. Air Force applications. To achieve a vacuum, internal gases are evacuated from the vessel, which creates a dynamic response in the supporting structural frame. This paper considers the frame of an icosahedron shaped LTAV subject to external atmospheric pressure evacuated at varying rates. A static finite element analysis documented in previous research revealed a snapback phenomenon in the frame members under certain loading conditions. A nonlinear chaotic response was observed when a dynamic analysis was conducted with the same boundary conditions used in the static analysis. The chaotic response for a variety of boundary conditions, generated by varying the rate of evacuation, similar to a ramp input, is determined. An analysis of the dynamic response is determined nonlinearly using a method that relies on a reference point distribution of external pressures to distribute the surface force across the frame. A novel method of combining the power spectral density with a Lyapunov exponent was used to determine the degree of nonlinearity and chaotic response for each boundary condition examined.

Three-Stage Multiscale Nonlinear Dynamic Analysis Platform for Building-Level Loss Estimation

2015 ◽  
Vol 31 (2) ◽  
pp. 1021-1042 ◽  
Author(s):  
In Ho Cho ◽  
Keith Porter
Keyword(s):  
Dynamic Analysis ◽  
Information Transfer ◽  
Large Scale ◽  
Nonlinear Dynamic Analysis ◽  
Loss Estimation ◽  
Element Analysis ◽  
Global Dynamic ◽  
Micro Level ◽  
Analysis Platform ◽  
Vulnerability Functions

Large-scale loss estimation needs vulnerability functions that relate ground motion to repair cost for each of many building classes. A challenge to generating analytical vulnerability functions for a building class is that one needs to reflect seismic performance at several scales, from the size of cracks to the whole building. Here, we propose a three-stage multiscale platform tackling a general reinforced concrete (RC) building containing complex walls: (1) at the micro level, a microphysical mechanism-based parallel finite element analysis (FEA) engine captures microscopic nonlinearities; (2) the macro level handles computationally expensive dynamic analyses of buildings; (3) the meso level manages interscale information transfer and describes floor-specific variability. Multiple parallel FEA engines run in concert with a stand-alone dynamic analysis platform. Importantly, the micro level resolves damage phenomena explicitly—no fragility inference is required—propagating component damage to global dynamic analysis. Now, one can link microscopic damage to building seismic loss.

Chaotic Behavior of Hydraulic Engine Mount

2006 ◽  
Author(s):  
J. Christopherson ◽  
G. Nakhaie Jazar ◽  
M. Mahinfalah
Keyword(s):  
Boundary Conditions ◽  
Chaotic Behavior ◽  
Hysteretic Behavior ◽  
Constitutive Relationship ◽  
Element Analysis ◽  
Engine Mounts ◽  
Fluid Behavior ◽  
Lumped Parameter ◽  
Engine Mount ◽  
Parameter Approach

The constitutive relationships of the rubber materials that act as the main spring of a hydraulic mount are nonlinear. In addition to material induced nonlinearity, further nonlinearities may be introduced by mount geometry, turbulent fluid behavior, boundary conditions, temperature, decoupler action, and hysteretic behavior. While all influence the behavior of the system only certain aspects are realistically considered using the lumped parameter approach employed in this research. The nonlinearities that are readily modeled by the lumped parameter approach constitute the geometry and constitutive relationship induced nonlinearity, including hysteretic behavior, noting that these properties all make an appearance in the load-deflection relationship for the mount and may be readily determined via experiment or flnite element analysis. In this paper we will shoe that under certain conditions, the nonlinearities involved in the hydraulic engine mounts can show a chaotic response.

Inelastic Dynamic Analysis of Steel Structure Using Force Analogy Method

2012 ◽  
Vol 166-169 ◽  
pp. 304-309 ◽  
Author(s):  
Shi Qiang Song ◽  
Gang Li
Keyword(s):  
Dynamic Analysis ◽  
Plastic Hinge ◽  
Nonlinear Dynamic Analysis ◽  
Steel Structure ◽  
Response Analysis ◽  
Analysis Method ◽  
Element Analysis ◽  
Analogy Method ◽  
Traditional Algorithm ◽  
Response State

Force analogy method is a kind of nonlinear dynamic analysis method. Analyzing inelastic structural behavior by using plastic hinge theory, it is widely appropriate to many structures with different material properties and very time efficient and numerically accurate without complicated iterative computations in traditional algorithm. Compared with the traditional finite-element analysis method, dynamic response analysis based on force analogy method has obvious advantages. The application of force analogy method to a steel structure is presented and the analysis result shows that the method algorithm can represent each response state of the structure in real-time and has the very good accuracy and practical.

Comparison of frequency- and time-domain analyses for guyed masts in turbulent winds

2006 ◽  
Vol 33 (2) ◽  
pp. 169-182 ◽  
Author(s):  
B F Sparling ◽  
L D Wegner
Keyword(s):  
Finite Element ◽  
Dynamic Response ◽  
Dynamic Analysis ◽  
Frequency Domain ◽  
Time Domain ◽  
Element Model ◽  
Mode Shapes ◽  
Nonlinear Behaviour ◽  
Element Analysis ◽  
Guyed Mast

Both frequency- and time-domain methods have been employed in the dynamic analysis of guyed telecommunication masts subjected to turbulent winds. Although the probabilistic frequency-domain approach offers some advantages in terms of its relative ease of implementation and in the statistical reliability of wind load descriptions, the deterministic time-domain method permits a more realistic treatment of system nonlinearities. In this study, a numerical investigation was undertaken to compare frequency- and time-domain dynamic response predictions for a selected guyed mast in gusty winds. Two different analysis techniques were employed, with the frequency-domain calculations performed using response influence lines and the time-domain analyses carried out using a stiffness-based finite element model. Good agreement was observed in root-mean-square and peak dynamic response estimates after compensation was included for differences in turbulence intensity levels assumed in the two models. In general, natural frequencies and mode shapes were also similar.Key words: guyed mast, dynamic analysis, wind, turbulence, nonlinear behaviour, finite element analysis, cables, frequency domain, time domain.

Dynamic Analysis of a Microscale Cricket Filiform Hair Socket

2015 ◽  
Author(s):  
A. Hossain ◽  
A. Mian
Keyword(s):  
Dynamic Response ◽  
Dynamic Analysis ◽  
Sensory System ◽  
Mems Devices ◽  
Low Velocity ◽  
Element Analysis ◽  
Physical Conditions ◽  
Fea Model ◽  
Filiform Hair ◽  
Spiking Activity

Filiform hairs of crickets are of great interest to engineers because of their highly sensitive response to low velocity air currents. In this study, the cercal sensory system of a common house cricket has been analyzed. The sensory system consists of two antennae like appendages called cerci that are situated at the rear of the cricket’s abdomen. Each cercus is covered with 500–750 flow sensitive hairs that are embedded in a complex viscoelastic socket that acts as a spring -dashpot system and guides the movement of the hair. When the hair deflects due to the drag force induced on its length by a moving air-current, the spiking activity of the neuron and the combined spiking activity of all hairs are extracted by the cercal sensory system. The hair has been experimentally studied by few researchers though its characteristics are not fully understood. The socket structure has not been analyzed experimentally or theoretically from a mechanical standpoint. Therefore, this study aims to understand the dynamic response of socket and its interaction with the filiform hair. First, a 3D Finite Element Analysis (FEA) model, representing hair and hair-socket, has been developed. Then the dynamic analysis is conducted utilizing the appropriate load and boundary conditions based on the physical conditions that an insect experiences. These numerical analyses aid to understand the dynamic response of the hair and hair-socket system. The operating principles of the hair and hair-socket could be used for the design of highly responsive MEMS devices such as fluid flow sensors or micro-manipulators.

Comportement dynamique des lignes aériennes de transport d'électricité dû aux bris de câbles. I. Modélisation mathématique

1989 ◽  
Vol 16 (3) ◽  
pp. 335-353 ◽  
Author(s):  
Ghyslaine McClure ◽  
René Tinawi
Keyword(s):  
Mathematical Model ◽  
Dynamic Analysis ◽  
Transmission Lines ◽  
Nonlinear Dynamic ◽  
Nonlinear Dynamic Analysis ◽  
Physical Models ◽  
Element Analysis ◽  
Electric Transmission ◽  
Electric Transmission Lines ◽  
Supporting Structures

This paper presents a mathematical model for the nonlinear dynamic analysis of aerial electric transmission lines subjected to conductor breakage. The model uses existing finite elements and validated numerical techniques available in most commercial programs capable of handling nonlinear dynamic analysis. ADINA is used in this study. In comparison with other models, the novel approach presented here focusses on the discretization of the conductors as well as the supporting structures, specially near the breakage point. Dynamic interactions between all the structural components are therefore considered and comparisons with simpler models emphasize the importance of these interactions, the effects of geometric nonlinearities present in the conductors and in the supporting structures, and the contribution of higher modes.The mathematical model is validated with 7 of 56 tests conducted on reduced-scale physical models, reported in work done for the American Electric Power Research Institute.The results of the present study are very encouraging for designers interested in validating their design criteria for longitudinal dynamic loads by use of existing nonlinear dynamic finite element analysis packages. Key words: Nonlinear dynamic analysis, electric transmission lines, conductor breakage simulation.

Semi-exact solution for nonlinear dynamic analysis of nanobeams reinforced with functionally graded carbon nanotube located on a viscoelastic foundation

2019 ◽  
Vol 233 (18) ◽  
pp. 6626-6639
Author(s):  
Ahmad Fallah ◽  
MB Dehkordi ◽  
YT Beni
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Dynamic Response ◽  
Dynamic Analysis ◽  
Nonlinear Dynamic ◽  
Nonlinear Coefficient ◽  
Nonlinear Dynamic Analysis ◽  
Functionally Graded ◽  
Nonlinear Frequency ◽  
Viscoelastic Foundation

In this investigation, a transient nonlinear dynamic analysis of nanobeams reinforced with carbon nanotubes, which is located on a nonlinear viscoelastic foundation under the impulse loading, is investigated. The boundary conditions of the nanobeam are considered as clamped-clamped, and the carbon nanotube is distributed in different distribution along the thickness of nanobeam. First, using the Hamiltonian method and taking advantage of the couple stress theory and considering the Von Karman relationship between strain and displacement, the differential equation governing for Euler–Bernoulli nanobeam is obtained. Then, by using the semi-exact method and the Galerkin's method, the displacement derivatives are separated from the time derivatives and the equation derived is solved using Runge–Kutta's numerical method. In order to confirm the equation and its solution, a comparative study is performed that shows an appropriate fitting between the results. Finally, the influence of parameters such as nonlinear coefficient of foundation, applied force, size effect, and type of nanotube distribution on the nonlinear frequency to linear frequency ratio and transient nanobeam dynamic response is investigated. A study is also conducted on the effect of foundation damping coefficient and the inclusion of nonlinear effects on the transient dynamic response when the nanobeam is under impulse load and resonance conditions. The results show that the nonlinear vibrational frequency of the nanobeam with the FG-X carbon nanotube distribution is the highest, and the FG-O carbon nanotubes distribution is the least.

A Simplified Design Model for Modular Steel Buildings Subject to Vapor Cloud Explosions (VCEs)

2020 ◽  
Vol 14 ◽  
Author(s):  
Osama Bedair
Keyword(s):  
Dynamic Response ◽  
Minimum Cost ◽  
Design Parameters ◽  
Front Wall ◽  
Steel Buildings ◽  
Element Analysis ◽  
Analysis And Design ◽  
Vapor Cloud ◽  
Building Components ◽  
Analytical Expressions

Background: Modular steel buildings (MSB) are extensively used in petrochemical plants and refineries. Limited guidelines are available in the industry for analysis and design of (MSB) subject to accidental vapor cloud explosions (VCEs). Objectives: The paper presents simplified engineering model for modular steel buildings (MSB) subject to accidental vapor cloud explosions (VCEs) that are extensively used in petrochemical plants and refineries. Method: A Single degree of freedom (SDOF) dynamic model is utilized to simulate the dynamic response of primary building components. Analytical expressions are then provided to compute the dynamic load factors (DLF) for critical building elements. Recommended foundation systems are also proposed to install the modular building with minimum cost. Results: Numerical results are presented to illustrate the dynamic response of (MSB) subject to blast loading. It is shown that (DLF)=1.6 is attained at (td/t)=0.4 for front wall (W1) with (td/T)=1.25. For side walls (DLF)=1.41 and is attained at (td/t)=0.6. Conclusions: The paper presented simplified tools for analysis and design of (MSB) subject accidental vapor cloud blast explosions (VCEs). The analytical expressions can be utilized by practitioners to compute the (MSB) response and identify the design parameters. They are simple to use compared to Finite Element Analysis.

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