On the Threshold Force for Chaotic Motions for a Forced Buckled Beam

1988 ◽  
Vol 55 (1) ◽  
pp. 190-196 ◽  
Author(s):  
D. M. Tang ◽  
E. H. Dowell
Keyword(s):  
Experimental Data ◽  
Numerical Simulations ◽  
System Response ◽  
Chaotic Oscillations ◽  
External Excitation ◽  
Chaotic Motions ◽  
Higher Modes ◽  
Threshold Force ◽  
Buckled Beam

The effects of higher modes on the chaotic oscillations of a buckled beam under forced external excitation are studied. Of principal interest are the threshold force required for chaotic motions and the influence of damping on the system response. A comparison is also presented of results from numerical simulations with experimental data.

On the Understanding of Chaos in Duffings Equation Including a Comparison With Experiment

1986 ◽  
Vol 53 (1) ◽  
pp. 5-9 ◽  
Author(s):  
E. H. Dowell ◽  
C. Pezeshki
Keyword(s):  
Theoretical Model ◽  
Initial Value Problem ◽  
Physical Experiment ◽  
Chaotic Oscillations ◽  
External Excitation ◽  
Initial Value ◽  
Comparison Of Results ◽  
Buckled Beam ◽  
Comparison With Experiment ◽  
Forced Excitation

The dynamics of a buckled beam are studied for both the initial value problem and forced external excitation. The principal focus is on chaotic oscillations due to forced excitation. In particular, a discussion of their relationship to the initial value problem and a comparison of results from a theoretical model with those from a physical experiment are presented.

Regular and chaotic oscillations of friction force

2006 ◽  
Vol 220 (3) ◽  
pp. 273-284 ◽  
Author(s):  
A Stefański ◽  
J Wojewoda ◽  
M Wiercigroch ◽  
T Kapitaniak
Keyword(s):  
Theoretical Analysis ◽  
Numerical Simulations ◽  
Friction Force ◽  
Experimental Research ◽  
Friction Model ◽  
System Response ◽  
Chaotic Oscillations ◽  
Dynamical Nature ◽  
Friction Models

In this paper, several friction features and models are discussed in the context of the dynamical nature of friction force observed during experiments. On the basis of experimental and theoretical analysis, the authors show that such behaviour can be considered as a certain representation of the system dynamics. According to this approach, a classification of friction models with respect to their sensitivity on the system motion character is introduced. Next, the results of experimental research are reported. Friction characteristics reconstructed experimentally for various types of the system response, i.e. periodic, quasi-periodic, and chaotic, are demonstrated. Finally, these results are compared with numerical simulations using the proposed friction model.

COMPARISON OF NUMERICAL SIMULATIONS WITH EXPERIMENTAL DATA FOR VERTICAL ANNULAR AND CHURN GAS-LIQUID FLOWS

2020 ◽  
Author(s):  
Larissa Steiger de Freitas ◽  
Marcus Vinícius Canhoto Alves ◽  
Rafael Rodrigues Francisco
Keyword(s):  
Experimental Data ◽  
Numerical Simulations ◽  
Liquid Flows

Effect of Interaction Modeling in AFM-Based Nanomanipulation

2008 ◽  
Author(s):  
Fakhreddine Landolsi ◽  
Fathi H. Ghorbel ◽  
James B. Dabney
Keyword(s):  
Experimental Data ◽  
Numerical Simulations ◽  
Interaction Model ◽  
Collision Process ◽  
Visual Sensing ◽  
Proposed Model ◽  
Interaction Modeling

AFM-based nanomanipulation is very challenging because of the complex mechanics in tip-sample interactions and the limitations in AFM visual sensing capabilities. In the present paper, we investigate the modeling of AFM-based nanomanipulation emphasizing the effects of the relevant interactions at the nanoscale. The major contribution of the present work is the use of a combined DMT-JKR interaction model in order to describe the complete collision process between the AFM tip and the sample. The coupling between the interactions and the friction at the nanoscale is emphasized. The efficacy of the proposed model to reproduce experimental data is demonstrated via numerical simulations.

The penetration and ricochet of ogive-nosed rigid projectiles obliquely impacting metallic targets

2021 ◽  
pp. 204141962110377
Author(s):  
Yaniv Vayig ◽  
Zvi Rosenberg
Keyword(s):  
Experimental Data ◽  
Numerical Simulations ◽  
Dynamic Pressure ◽  
Oblique Impacts ◽  
Simulation Results ◽  
The Impact ◽  
Penetration Depths ◽  
Resistance To Penetration ◽  
Good Agreement

A large number of 3D numerical simulations were performed in order to follow the trajectory changes of rigid CRH3 ogive-nosed projectiles, impacting semi-infinite metallic targets at various obliquities. These trajectory changes are shown to be related to the threshold ricochet angles of the projectile/target pairs. These threshold angles are the impact obliquities where the projectiles end up moving in a path parallel to the target’s face. They were found to depend on a non-dimensional entity which is equal to the ratio between the target’s resistance to penetration and the dynamic pressure exerted by the projectile upon impact. Good agreement was obtained by comparing simulation results for these trajectory changes with experimental data from several published works. In addition, numerically-based relations were derived for the penetration depths of these ogive-nosed projectiles at oblique impacts, which are shown to agree with the simulation results.

The probe particle scattering cross-section off the many-fermion systems in the impulse approximation

2021 ◽  
Author(s):  
Yahya Younesizadeh ◽  
Fayzollah Younesizadeh
Keyword(s):  
Experimental Data ◽  
Distribution Function ◽  
Spectral Function ◽  
Cross Section ◽  
Response Function ◽  
Momentum Distribution ◽  
Impulse Approximation ◽  
System Response ◽  
Probe Particle ◽  
Momentum Distribution Function

In this work, we study the differential scattering cross-section (DSCS) in the first-order Born approximation. It is not difficult to show that the DSCS can be simplified in terms of the system response function. Also, the system response function has this property to be written in terms of the spectral function and the momentum distribution function in the impulse approximation (IA) scheme. Therefore, the DSCS in the IA scheme can be formulated in terms of the spectral function and the momentum distribution function. On the other hand, the DSCS for an electron off the [Formula: see text] and [Formula: see text] nuclei is calculated in the harmonic oscillator shell model. The obtained results are compared with the experimental data, too. The most important result derived from this study is that the calculated DSCS in terms of the spectral function has a high agreement with the experimental data at the low-energy transfer, while the obtained DSCS in terms of the momentum distribution function does not. Therefore, we conclude that the response of a many-fermion system to a probe particle in IA must be written in terms of the spectral function for getting accurate theoretical results in the field of collision. This is another important result of our study.

Numerical Simulations as a Reliable Alternative for Landmine Explosion Studies: The AUTODYN Approach

2010 ◽  
Author(s):  
Stephanie Follett ◽  
Amer Hameed ◽  
S. Darina ◽  
John G. Hetherington
Keyword(s):  
Experimental Data ◽  
Numerical Simulations ◽  
Reasonable Agreement ◽  
Specific Impulse ◽  
Numerical Procedure ◽  
Ground Surface ◽  
Time Of Arrival ◽  
Linear Dynamics ◽  
Non Linear

In order to validate the numerical procedure, the explosion of a mine was recreated within the non-linear dynamics software, AUTODYN. Two models were created and analysed for the purposes of this study — buried and flush HE charge in sand. The explosion parameters — time of arrival, maximum overpressure and specific impulse were recorded at two stand-off distances above the ground surface. These parameters are then compared with LS-DYNA models and published experimental data. The results, presented in table format, are in reasonable agreement.

Rounded Fin Edge and Step Position Effects on Discharge Coefficient in Rotating Labyrinth Seals

2015 ◽  
Vol 138 (1) ◽  
Author(s):  
Andrea Rapisarda ◽  
Alessio Desando ◽  
Elena Campagnoli ◽  
Roberto Taurino
Keyword(s):  
Experimental Data ◽  
Numerical Simulations ◽  
Leading Edge ◽  
Experimental Tests ◽  
Velocity Profiles ◽  
Pollutant Emission ◽  
Leakage Flow ◽  
Labyrinth Seals ◽  
Position Effects ◽  
Impact Reduction

The design of modern aircrafts propulsion systems is strongly influenced by the important objective of environmental impact reduction. Through a great number of researches carried out in the last decades, significant improvements have been obtained in terms of lower fuel consumption and pollutant emission. Experimental tests are a necessary step to achieve new solutions that are more efficient than the current designs, even if during the preliminary design phase, a valid alternative to expensive experimental tests is the implementation of numerical models. The processing power of modern computers allows indeed the simulation of more complex and detailed phenomena than the past years. The present work focuses on the implementation of a numerical model for rotating stepped labyrinth seals installed in low-pressure turbines. These components are widely employed in sealing turbomachinery to reduce the leakage flow between rotating components. The numerical simulations were performed by using computational fluid dynamics (CFD) methodology, focusing on the leakage performances at different rotating speeds and inlet preswirl ratios. Investigations on velocity profiles into seal cavities were also carried out. To begin with, a smooth labyrinth seal model was validated by using the experimental data found in the literature. The numerical simulations were extended to the honeycomb labyrinth seals, with the validation performed on the velocity profiles. Then, the effects of two geometrical parameters, the rounded fin tip leading edge, and the step position were numerically investigated for both smooth and honeycomb labyrinth seals. The obtained results are generally in good agreement with the experimental data. The main effect found when the fin tip leading edge was rounded was a large increase in leakage flow, while the step position contribution to the flow path behavior is nonmonotone.

scholarly journals Influence of Induction Hardening on Wear Resistance in Case of Rolling Contact

2016 ◽  
Vol 66 (1) ◽  
pp. 17-26 ◽  
Author(s):  
Michal Šofer ◽  
Rostislav Fajkoš ◽  
Radim Halama
Keyword(s):  
Experimental Data ◽  
Numerical Simulations ◽  
Induction Hardening ◽  
Rolling Contact ◽  
Isotropic Hardening ◽  
Wear Model ◽  
Wear Rates ◽  
C Programming Language ◽  
Hardening Rule ◽  
C Programming

AbstractThe main aim of the presented paper is to show how heat treatment, in our case the induction hardening, will affect the wear rates as well as the ratcheting evolution process beneath the contact surface in the field of line rolling contact. Used wear model is based on shear band cracking mechanism [1] and non-linear kinematic and isotropic hardening rule of Chaboche and Lemaitre. The entire numerical simulations have been realized in the C# programming language. Results from numerical simulations are subsequently compared with experimental data.

scholarly journals Quantitative Assessment of the Influence of Tensile Softening of Concrete in Beams under Bending by Numerical Simulations with XFEM and Cohesive Cracks

Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 626
Author(s):  
Ireneusz Marzec ◽  
Jerzy Bobiński
Keyword(s):  
Experimental Data ◽  
Numerical Simulations ◽  
Extended Finite Element ◽  
Three Point Bending ◽  
Material Parameters ◽  
Error Measures ◽  
Rational Bézier Curve ◽  
Initial Fracture ◽  
Experimental Values ◽  
Tensile Softening

Results of the numerical simulations of the size effect phenomenon for concrete in comparison with experimental data are presented. In-plane geometrically similar notched and unnotched beams under three-point bending are analyzed. EXtended Finite Element Method (XFEM) with a cohesive softening law is used. Comprehensive parametric study with the respect to the tensile strength and the initial fracture energy is performed. Sensitivity of the results with respect to the material parameters and the specimen geometry is investigated. Three different softening laws are examined. First, a bilinear softening definition is utilized. Then, an exponential curve is taken. Finally, a rational Bezier curve is tested. An ambiguity in choosing material parameters and softening curve definitions is discussed. Numerical results are compared with experimental outcomes recently reported in the literature. Two error measures are defined and used to quantitatively assess calculated maximum forces (nominal strengths) in comparison with experimental values as a primary criterion. In addition, the force—displacement curves are also analyzed. It is shown that all softening curves produce results consistent with the experimental data. Moreover, with different softening laws assumed, different initial fracture energies should be taken to obtain proper results.

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