Nonlinear Material Damping for Nonsinusoidal Strain

1978 ◽  
Vol 45 (4) ◽  
pp. 883-888 ◽  
Author(s):  
R. Plunkett ◽  
M. Sax
Keyword(s):  
Steady State ◽  
Nonlinear Damping ◽  
The Other ◽  
Nonlinear Material ◽  
Damping Factor ◽  
Cantilever Beams ◽  
At Resonance ◽  
Highly Nonlinear ◽  
Second Mode ◽  
Mode Vibration

The damping in uniform and nonuniform cantilever beams was measured at resonance for a range of amplitudes of simultaneous steady-state first and second mode vibration. For two linear materials, aluminum and crossply fiberglas, the damping factor in each mode is independent of amplitude and unaffected by the presence of the other mode. For a fully annealed tool steel with highly nonlinear damping, the damping factor in each mode is markedly increased by the presence of the other mode.

Fidelity of J1269 and J24523

2007 ◽  
Vol 35 (2) ◽  
pp. 94-117 ◽  
Author(s):  
James A. Popio ◽  
John R. Luchini
Keyword(s):  
Steady State ◽  
Rolling Resistance ◽  
Test Methods ◽  
The Other ◽  
Reference Condition ◽  
Test Standards

Abstract This study compares data from the two Society of Automotive Engineers test methods for rolling resistance: J-2452 (Stepwise Coast-Down) and J-1269 (Equilibrium) steady state. The ability of the two methods to evaluate tires was examined by collecting data for 12 tires. The data were analyzed and the data showed that the two methods ranked the tires the same after the data were regressed and the rolling resistance magnitude was calculated at the Standard Reference Condition. In addition, analysis of the two methods using this matched set of testing provided an opportunity to evaluate each of these test standards against the other. It was observed that each test has merits absent from the other.

scholarly journals Receptor-operated Ca2+ channels in gastric parietal cells: gastrin and carbachol induce Ca2+ influx in depleting intracellular Ca2+ stores

1993 ◽  
Vol 289 (1) ◽  
pp. 117-124 ◽  
Author(s):  
S Roche ◽  
J P Bali ◽  
R Magous
Keyword(s):  
Steady State ◽  
Receptor Activation ◽  
Parietal Cells ◽  
The Other ◽  
Bivalent Cation ◽  
Gtp Binding ◽  
Gastric Parietal Cells ◽  
Type Receptor ◽  
Ca2 Channels ◽  
Stimulation Of

The mechanism whereby gastrin-type receptor and muscarinic M3-type receptor regulate free intracellular Ca2+ concentration ([Ca2+]i) was studied in rabbit gastric parietal cells stimulated by either gastrin or carbachol. Both agonists induced a biphasic [Ca2+]i response: a transient [Ca2+]i rise, followed by a sustained steady state depending on extracellular Ca2+. Gastrin and carbachol also caused a rapid and transient increase in Mn2+ influx (a tracer for bivalent-cation entry). Pre-stimulation of cells with one agonist drastically decreased both [Ca2+]i increase and Mn2+ influx induced by the other. Neither diltiazem nor pertussistoxin treatment had any effect on agonist-stimulated Mn2+ entry. Thapsigargin, a Ca(2+)-pump inhibitor, induced a biphasic [Ca2+]i increase, and enhanced the rate of Mn2+ entry. Preincubation of cells with thapsigargin inhibits the [Ca2+]i increase as well as Mn2+ entry stimulated by gastrin or by carbachol. Thapsigargin induced a weak but significant increase in Ins(1,4,5)P3 content, but this agent had no effect on the agonist-evoked Ins(1,4,5)P3 response. In permeabilized parietal cells, Ins(1,4,5)P3 and caffeine caused an immediate Ca2+ release from intracellular pools, followed by a reloading of Ca2+ pools which can be prevented in the presence of thapsigargin. We conclude that (i) gastrin and carbachol mobilize common Ca2+ intracellular stores, (ii) Ca2+ permeability secondary to receptor activation involves neither a voltage-sensitive Ca2+ channel nor a GTP-binding protein from the G1 family, and (iii) agonists regulate common Ca2+ channels in depleting intracellular Ca2+ stores.

scholarly journals Visco-Hyperelastic Characterization of the Equine Immature Zona Pellucida

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1223
Author(s):  
Elisa Ficarella ◽  
Mohammad Minooei ◽  
Lorenzo Santoro ◽  
Elisabetta Toma ◽  
Bartolomeo Trentadue ◽  
...  
Keyword(s):  
Zona Pellucida ◽  
Soft Matter ◽  
Mechanical Response ◽  
Mechanical Characterization ◽  
Nonlinear Material ◽  
Prony Series ◽  
Critical Comparison ◽  
Highly Nonlinear ◽  
Good Agreement

This article presents a very detailed study on the mechanical characterization of a highly nonlinear material, the immature equine zona pellucida (ZP) membrane. The ZP is modeled as a visco-hyperelastic soft matter. The Arruda–Boyce constitutive equation and the two-term Prony series are identified as the most suitable models for describing the hyperelastic and viscous components, respectively, of the ZP’s mechanical response. Material properties are identified via inverse analysis based on nonlinear optimization which fits nanoindentation curves recorded at different rates. The suitability of the proposed approach is fully demonstrated by the very good agreement between AFM data and numerically reconstructed force–indentation curves. A critical comparison of mechanical behavior of two immature ZP membranes (i.e., equine and porcine ZPs) is also carried out considering the information on the structure of these materials available from electron microscopy investigations documented in the literature.

POVERTY TRAPS AND INFERIOR GOODS IN A DYNAMIC HECKSCHER–OHLIN MODEL

2012 ◽  
Vol 17 (6) ◽  
pp. 1227-1251 ◽  
Author(s):  
Eric W. Bond ◽  
Kazumichi Iwasa ◽  
Kazuo Nishimura
Keyword(s):  
Economic Theory ◽  
Steady State ◽  
World Economy ◽  
Steady States ◽  
The Other ◽  
Poverty Traps ◽  
Poverty Trap ◽  
Multiple Steady States ◽  
The World ◽  
State Capital

We extend the dynamic Heckscher–Ohlin model in Bond et al. [Economic Theory(48, 171–204, 2011)] and show that if the labor-intensive good is inferior, then there may exist multiple steady states in autarky and poverty traps can arise. Poverty traps for the world economy, in the form of Pareto-dominated steady states, are also shown to exist. We show that the opening of trade can have the effect of pulling the initially poorer country out of a poverty trap, with both countries having steady state capital stocks exceeding the autarky level. However, trade can also pull an initially richer country into a poverty trap. These possibilities are a sharp contrast with dynamic Heckscher–Ohlin models with normality in consumption, where the country with the larger (smaller) capital stock than the other will reach a steady state where the level of welfare is higher (lower) than in the autarkic steady state.

Electron drift caused by rf field gradient creates many plasma phenomena: An attempt to distinguish the cause and the effect

2011 ◽  
Vol 78 (2) ◽  
pp. 165-174 ◽  
Author(s):  
C. L. XAPLANTERIS ◽  
E. D. FILIPPAKI ◽  
I. S. MISTAKIDIS ◽  
L. C. XAPLANTERIS
Keyword(s):  
Experimental Data ◽  
Steady State ◽  
Low Temperature ◽  
Mathematical Models ◽  
Field Gradient ◽  
Collision Frequency ◽  
The Other ◽  
Frequency Effect ◽  
Electron Drift ◽  
Plasma Parameters

AbstractMany experimental data along with their theoretical interpretations on the rf low-temperature cylindrical plasma have been issued until today. Our Laboratory has contributed to that research by publishing results and interpretative mathematical models. With the present paper, two issues are being examined; firstly, the estimation of electron drift caused by the rf field gradient, which is the initial reason for the plasma behaviour, and secondly, many new experimental results, especially the electron-neutral collision frequency effect on the other plasma parameters and quantities. Up till now, only the plasma steady state was taken into consideration when a theoretical elaboration was carried out, regardless of the cause and the effect. This indicates the plasma's complicated and chaotic configuration and the need to simplify the problem. In the present work, a classification about the causality of the phenomena is attempted; the rf field gradient electron drift is proved to be the initial cause.

Response surface method strategies coupled with NLFEA for structural reliability analysis of prestressed bridges

2021 ◽  
Author(s):  
Silvia J. Sarmiento Nova ◽  
Jaime Gonzalez-Libreros ◽  
Gabriel Sas ◽  
Rafael A. Sanabria Díaz ◽  
Maria C. A. Texeira da Silva ◽  
...  
Keyword(s):  
Reliability Analysis ◽  
Response Surface ◽  
Response Surface Method ◽  
Structural Reliability ◽  
Limit State ◽  
Material Behavior ◽  
Nonlinear Material ◽  
State Function ◽  
Surface Method ◽  
Highly Nonlinear

<p>The Response Surface Method (RSM) has become an essential tool to solve structural reliability problems due to its accuracy, efficacy, and facility for coupling with Nonlinear Finite Element Analysis (NLFEA). In this paper, some strategies to improve the RSM efficacy without compromising its accuracy are tested. Initially, each strategy is implemented to assess the safety level of a highly nonlinear explicit limit state function. The strategy with the best results is then identified and used to carry out a reliability analysis of a prestressed concrete bridge, considering the nonlinear material behavior through NLFEA simulation. The calculated value of &#120573; is compared with the target value established in Eurocode for ULS. The results showed how RSM can be a practical methodology and how the improvements presented can reduce the computational cost of a traditional RSM giving a good alternative to simulation methods such as Monte Carlo.</p>

scholarly journals Effectiveness Testing of an Inverse Method for Balancing Nonlinear Rotordynamic Systems

2018 ◽  
Author(s):  
Sergio G. Torres Cedillo ◽  
Philip Bonello ◽  
Ghaith Ghanim Al-Ghazal ◽  
Jacinto Cortés Pérez ◽  
Alberto Reyes Solis
Keyword(s):  
Inverse Problem ◽  
Inverse Method ◽  
Linear Connection ◽  
The Other ◽  
Squeeze Film ◽  
Squeeze Film Damper ◽  
Operational Conditions ◽  
Non Invasive ◽  
Highly Nonlinear ◽  
Aero Engine

Modern aero-engine structures typically have at least two nested rotors mounted within a flexible casing via squeeze-film damper (SFD) bearings. The inaccessibility of the HP rotor under operational conditions motivates the use of a non-invasive inverse problem procedure for identifying the unbalance. Such an inverse problem requires prior knowledge of the structure and measurements of the vibrations at the casing. Recent work by the authors reported a non-invasive inverse method for the balancing of rotordynamic systems with nonlinear squeeze-film damper (SFD) bearings, which overcomes several limitations of earlier works. However, it was not applied to a common practical configuration wherein the HP rotor is mounted on the casing via just one weak linear connection (retainer spring), with the other connections being highly nonlinear SFDs. The analysis of the present paper considers such a system. It explores the influence of the condition number and how it is affected as the number of sensors and/or measurement speeds is increased. The results show that increasing the number of measurement speeds has a far more significant impact on the conditioning of the problem than increasing the number of sensors. The balancing effectiveness is reasonably good under practical noise level conditions, but significantly lower than obtained for the previously considered simpler configurations.

scholarly journals ENDOGENOUS BORROWING CONSTRAINTS AND WEALTH INEQUALITY

2016 ◽  
Vol 20 (6) ◽  
pp. 1413-1431 ◽  
Author(s):  
Joydeep Bhattacharya ◽  
Xue Qiao ◽  
Min Wang
Keyword(s):  
Steady State ◽  
Credit Market ◽  
Wealth Inequality ◽  
Borrowing Constraints ◽  
Initial Distribution ◽  
The Other ◽  
Capital Investments ◽  
Loan Default ◽  
Long Run ◽  
Human Capital Investments

This paper studies the evolution of wealth inequality in an economy with endogenous borrowing constraints. In the model economy, young agents need to borrow to finance human capital investments but cannot commit to repaying their loans. Creditors can punish defaulters by banishing them permanently from the credit market. At equilibrium, loan default is prevented by imposing a borrowing limit tied to the borrower's inheritance. The heterogeneity in inheritances translates into heterogeneity in borrowing limits: endogenously, some borrowers face a zero borrowing limit, and some are partly constrained, whereas others are unconstrained. Depending on the initial distribution of inheritances, it is possible that all lineages are attracted either to the zero-borrowing-limit steady state or to the unconstrained-borrowing steady state—long-run equality. It is also possible that some lineages end up in one steady state and the rest in the other—complete polarization.

Stability and resonance conditions of second-order fractional systems

2016 ◽  
Vol 24 (4) ◽  
pp. 659-672 ◽  
Author(s):  
Elena Ivanova ◽  
Xavier Moreau ◽  
Rachid Malti
Keyword(s):  
Second Order ◽  
Damping Factor ◽  
Fractional Differentiation ◽  
Resonance Amplitude ◽  
Fractional Systems ◽  
Integral Number ◽  
At Resonance ◽  
Fractional System ◽  
The Stability ◽  
Normalized Gain

The interest of studying fractional systems of second order in electrical and mechanical engineering is first illustrated in this paper. Then, the stability and resonance conditions are established for such systems in terms of a pseudo-damping factor and a fractional differentiation order. It is shown that a second-order fractional system might have a resonance amplitude either greater or less than one. Moreover, three abaci are given allowing the pseudo-damping factor and the differentiation order to be determined for, respectively, a desired normalized gain at resonance, a desired phase at resonance, and a desired normalized resonant frequency. Furthermore, it is shown numerically that the system root locus presents a discontinuity when the fractional differentiation order is an integral number.

scholarly journals Finite Element Software for Rubber Products Design

2018 ◽  
Vol 3 (1) ◽  
pp. 13-20
Author(s):  
Dávid Huri
Keyword(s):  
Finite Element ◽  
Complex Analysis ◽  
Large Deformations ◽  
Material Behavior ◽  
Nonlinear Material ◽  
Material Models ◽  
Finite Element Software ◽  
Highly Nonlinear ◽  
Wide Range ◽  
Different Types

Automotive rubber products are subjected to large deformations during working conditions, they often contact with other parts and they show highly nonlinear material behavior. Using finite element software for complex analysis of rubber parts can be a good way, although it has to contain special modules. Different types of rubber materials require the curve fitting possibility and the wide range choice of the material models. It is also important to be able to describe the viscoelastic property and the hysteresis. The remeshing possibility can be a useful tool for large deformation and the working circumstances require the contact and self contact ability as well. This article compares some types of the finite element software available on the market based on the above mentioned features.

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