Leveraging the Equivalence of Hysteresis Models From Different Fields for Analysis and Numerical Simulation of Jointed Structures

2008 ◽  
Vol 3 (3) ◽  
Author(s):  
T. J. Royston
Keyword(s):  
Large Scale ◽  
Structural Model ◽  
Constitutive Models ◽  
Hysteretic Behavior ◽  
Joint Interface ◽  
Element Analysis ◽  
Wide Range ◽  
Joint Dynamics ◽  
Analytical Tools ◽  
The Relationship

An important problem that spans across many types of systems (e.g., mechanical and biological) is how to model the dynamics of joints or interfaces in built-up structures in such a way that the complex dynamic and energy-dissipative behavior that depends on microscale phenomena at the joint/interface is accurately captured, yet in a framework that is amenable to efficient computational analyses of the larger macroscale system of which the joint or interface is a (spatially) small part. Simulating joint behavior in finite element analysis by meshing the joint regions finely enough to capture relevant micromechanics is impractical for large-scale structural systems. A more practical approach is to devise constitutive models for the overall behavior of individual joints that accurately capture their nonlinear and energy-dissipative behavior and to locally incorporate the constitutive response into the otherwise often-linear structural model. Recent studies have successfully captured and simulated mechanical joint dynamics using computationally simple phenomenological models of combined elasticity and slip with associated friction and energy dissipation, known as Iwan models. In the present article, the author reviews the relationship, and in some cases equivalence, of one type of Iwan model to several other models of hysteretic behavior that have been used to simulate a wide range of physical phenomena. Specifically, it is shown that the “parallel-series” Iwan model has been referred to in other fields by different names, including “Maxwell resistive capacitor,” “Ishlinskii,” and “ordinary stop hysteron.” Given this, the author establishes the relationship of this Iwan model to several other hysteresis models, most significantly the classical Preisach model. Having established these relationships, it is then possible to extend analytical tools developed for a specific hysteresis model to all of the models with which it is related. Such analytical tools include experimental identification, inversion, and analysis of vibratory energy flow and dissipation. Numerical case studies of simple systems that include an Iwan-modeled joint illustrate these points.

Leveraging the Equivalence of Hysteresis Models From Different Fields for Analysis and Numerical Simulation of Jointed Structures

2007 ◽  
Author(s):  
Thomas Royston
Keyword(s):  
Large Scale ◽  
Structural Model ◽  
Small Time ◽  
Hysteretic Behavior ◽  
Joint Interface ◽  
Element Analysis ◽  
Wide Range ◽  
Macro Scale ◽  
Analytical Tools ◽  
The Relationship

An important problem that spans across many types of systems (e.g. mechanical and biological) is how to model the dynamics of joints or interfaces in built-up structures in such a way that the complex dynamic and energy dissipative behavior that depends on micro-scale phenomena at the joint/interface is accurately captured, yet in a framework that is amenable to efficient computational analyses of the larger macro-scale system of which the joint or interface is a (spatially) small part. Simulating joint behavior in finite element analysis by meshing the joint regions finely enough to capture relevant micromechanics is impractical for large-scale structural systems due to the prohibitively small time steps required and/or resulting matrix ill-conditioning. A more practical approach is to devise constitutive models for the overall behavior of individual joints that accurately capture their nonlinear and energy-dissipative behavior and to incorporate the constitutive response locally into the otherwise often-linear structural model. Recent studies have successfully captured and simulated mechanical joint dynamics using computationally simple phenomenological models of combined elasticity and slip with associated friction and energy dissipation, known as Iwan models. In the present article, the author reviews the relationship, and in some cases exact equivalence, of one type of Iwan model to several other models of hysteretic behavior that have been used to simulate a wide range of physical phenomena. Specifically, it is shown that the “parallel-series” Iwan model has been referred to in other fields by different names, including “Maxwell Resistive-Capacitor” and “Ishlinskii”. Given this, the author establishes the relationship of this Iwan model to several other hysteresis models, most significantly the classical Preisach model. Having established these relationships, it is then possible to extend analytical tools developed for a specific hysteresis model to all of the models with which it is related. Such analytical tools include experimental identification, inversion and analysis of vibratory energy flow and dissipation. A numerical case study of a simple system that includes an Iwan-modeled joint illustrates these points.

scholarly journals DESTABILIZING EFFECTS OF BANK OVERLEVERAGING ON REAL ACTIVITY—AN ANALYSIS BASED ON A THRESHOLD MCS-GVAR

2017 ◽  
Vol 22 (7) ◽  
pp. 1750-1768 ◽  
Author(s):  
Marco Gross ◽  
Jerome Henry ◽  
Willi Semmler
Keyword(s):  
Regime Switching ◽  
Large Scale ◽  
Banking System ◽  
Real Activity ◽  
Vector Autoregressive ◽  
Joint Dynamics ◽  
Global Vector ◽  
Optimal Leverage ◽  
The Relationship ◽  
Activity Dependent

We investigate the consequences of overleveraging and the potential for destabilizing effects arising from financial- and real-sector interactions. In a theoretical framework, we model overleveraging and demonstrate how a highly leveraged banking system can lead to unstable dynamics and downward spirals. Inspired by models developed by Brunnermeier, Sannikov and Stein, we empirically measure the deviation-from-optimal-leverage for a sample of large EU banks. This measure of overleveraging is used to condition the joint dynamics of credit flows and macroeconomic activity in a large-scale regime change model: a Threshold Mixed-Cross-Section Global Vector Autoregressive (T-MCS-GVAR). The regime-switching component of the model is meant to make the relationship between credit and real activity dependent on the extent to which the banking system is overleveraged. We find significant nonlinearities as a function of overleverage. The farther the observed leverage in the banking system from optimal leverage, the more detrimental is the effect of a deleveraging shock on credit supply and economic activity.

Parametric FEA Study of Burst Pressure of Cylindrical Shell Intersections

2010 ◽  
Vol 132 (3) ◽  
Author(s):  
L. Xue ◽  
G. E. O. Widera ◽  
Z. Sang
Keyword(s):  
Finite Element ◽  
Cylindrical Shell ◽  
Pressure Vessel ◽  
Correlation Equation ◽  
Burst Pressure ◽  
Element Analysis ◽  
Wide Range ◽  
Deflection Analysis ◽  
Shell Intersections ◽  
The Relationship

In an earlier paper (2009, “Burst Pressure of Pressurized Cylinders With the Hillside Nozzle,” ASME J. Pressure Vessel Technol., 131(4), p. 041204), an elastic-plastic large deflection analysis method was used to determine the burst pressure and fracture location of hillside cylindrical shell intersections by use of nonlinear finite element analysis. To verify the accuracy of the finite element results, experimental burst tests were carried out by pressurizing test vessels with nozzles to burst. Based on the agreement between the numerical simulations and experimental results of Wang et al. (2009, “Burst Pressure of Pressurized Cylinders With the Hillside Nozzle,” ASME J. Pressure Vessel Technol., 131(4), p. 041204), a parametric study is now carried out. Its purpose is to develop a correlation equation by investigating the relationship between various geometric parameters (d/D, D/T, and t/T) and the burst pressure. Forty-seven configurations, which are deemed to cover most of the practical cases, are chosen to perform this study. In addition, four different materials are employed to verify that the proposed equation can be employed for different materials. The results show that the proposed equation resulting from the parametric analysis can be employed to predict the static burst pressure of cylindrical shell intersections for a wide range of geometric ratios.

Study on Electronic Industry with an Application of Rectilinear Embedding in VLSI Placement

2013 ◽  
Vol 345 ◽  
pp. 355-358
Author(s):  
Li Yan Pan ◽  
Yan Pei Liu
Keyword(s):  
Large Scale ◽  
Outerplanar Graph ◽  
Electronic Industry ◽  
Lagrangian Inversion ◽  
Multiple Parameters ◽  
Vlsi Physical Design ◽  
Wide Range ◽  
Large Scale Integration ◽  
Scale Integration ◽  
The Relationship

The electronic industry has developed quickly in last few years, with the rapid growth of Very Large Scale Integration technology. Placement layout is considered as the original step in VLSI physical design. The rectilinear embedding, which originates from graph theory, has wide range of application in VLSI placement. In this paper, we constructed a mathematical model for VLSI placement. Firstly, the VLSI placement was converted to quadrangulation by using rectilinear embedding speculative knowledge. Then we provided generating functions for two types of quadrangulations with graph multiple parameters. And the explicit formulae were obtained by employing Lagrangian inversion. Furthermore, we found the relationship between outerplanar graph and Hamilton graph, so the counting result of Hamilton quadrangulation was derived. The quadrangulation calculation can be applied to the establishment of arithmetical algorithms, which can be widely used in the optimization of VLSI placement.

Hardness obtained from conical indentations with various cone angles

2000 ◽  
Vol 15 (12) ◽  
pp. 2830-2835 ◽  
Author(s):  
Yang-Tse Cheng ◽  
Zhiyong Li
Keyword(s):  
Finite Element Analysis ◽  
Cone Angle ◽  
Relative Size ◽  
Contact Radius ◽  
Element Analysis ◽  
Wide Range ◽  
Line Theory ◽  
Simulation Results ◽  
The Relationship ◽  
Present Simulation

The relationship between hardness and cone angle of conical indenters was studied using finite element analysis for elastic–plastic solids with work-hardening. Comparisons were made between the present simulation results, slip line theory, and experimental results. Tabor's concept of representative strain based on indentation experiments in metals (The Hardness of Metals, Oxford, 1951) was shown to be applicable to a wide range of materials. The relative size of plastic zone with respect to the contact radius was found to influence the variation of hardness with indenter cone angle. The method proposed by Atkins and Tabor [J. Mech. Phys. Solids, 13, 149 (1965)] for constructing stress-strain curves using representative strains was also examined, and the conditions under which the method is valid were obtained.

Comparative Analysis of Terrorists’ Objectives Hierarchies

2020 ◽  
Vol 17 (2) ◽  
pp. 97-114
Author(s):  
Johannes Ulrich Siebert ◽  
Detlof von Winterfeldt
Keyword(s):  
Large Scale ◽  
Al Qaeda ◽  
Small Scale ◽  
Islamic State ◽  
The West ◽  
Analysis Methodology ◽  
Intelligence Collection ◽  
Wide Range ◽  
Terrorist Groups ◽  
The Relationship

To develop effective counterterrorism strategies, it is important to understand the capabilities and objectives of terrorist groups. Much of the understanding of these groups comes from intelligence collection and analysis of their capabilities. In contrast, the objectives of terrorists are less well understood. In this article, we describe a decision analysis methodology to identify and structure the objectives of terrorists based on the statements and writings of their leaders. This methodology was applied in three case studies, resulting in the three objectives hierarchies of al-Qaeda, Islamic State of Iraq and the Levant (ISIL), and Hezbollah. In this article, we propose a method to compare the three objectives hierarchies, highlight their key differences, and draw conclusions about effective counterterrorism strategies. We find that all three terrorist groups have a wide range of objectives going far beyond the objective of killing and terrorizing people in the non-Muslim world. Among the shared objectives are destroying Israel and expelling Western powers from the Middle East. All three groups share the ambition to become a leader in the Islamic world. Key distinctions are the territorial ambitions of ISIL and Hezbollah versus the large-scale attack objectives of al-Qaeda. Objectives specific to ISIL are the establishment of a caliphate in Iraq and Syria and the re-creation of the power of Sunni Islam. Hezbollah has unique objectives related to the establishment of a Palestine State and to maintain the relationship with and support of Iran and Syria. Al-Qaeda’s objectives remain focused on large-scale attacks in the West. We also note a recent shift to provide support for small-scale attacks in the West by both al-Qaeda and ISIL. Our method can be used for comparing objectives hierarchies of different organizations as well as for comparing objectives hierarchies over time of one organization.

Synthesis of 1D Regular Arrays of Gold Nanoparticles and Modeling of Their Optical Properties

2008 ◽  
Vol 8 (2) ◽  
pp. 564-571 ◽  
Author(s):  
N. Dmitruk ◽  
T. Barlas ◽  
A. Dmytruk ◽  
A. Korovin ◽  
V. Romanyuk
Keyword(s):  
Gold Nanoparticles ◽  
Large Scale ◽  
Polarized Light ◽  
Semiconductor Surface ◽  
Gold Deposition ◽  
Metal Nanowires ◽  
Element Analysis ◽  
Semiconductor Interface ◽  
Efficient Access ◽  
Wide Range

Self-organized formation of uniform coating of semiconductor substrate by metal nanoparticles offers a convenient and efficient access to large-scale arrays of uniform metal-semiconductor nanostructures. We used a cheap and facile method of photoinduced chemical gold deposition from an aqueous or alcohol gold salt solution onto semiconductor surface (GaAs, InP). By controlling of both the solution composition and the deposition conditions, gold particles of 10–50 nm in diameter were obtained and the gold covering degree of the semiconductor surface was varied in a wide range. Morphology of the nano/micro structures formed was characterized by atomic force microscopy and scanned electron microscopy with local element analysis. The investigations show that the semiconductor surface patterning can be used for the selective deposition of gold nanoparticles, because they are located predominantly at the tops of the microrelief. We have used specially textured by the anisotropic chemical etching microrelief surfaces of semiconductor single crystal as templates and have obtained nanoparticle arrays in the shape of 1D systems of near parallel quasiperiodical wires. For the periodic 1D array of metal nanowires built into the air-semiconductor interface the spectral and angular dependencies of the transmittance/reflectance of the polarized light have been obtained theoretically using differential formalism. These dependencies demonstrate non-monotonic behaviour at surface plasmon polariton excitation conditions and show possibility of designing functional subwavelength devices.

Experimental Study on Hysteretic Behavior of Circular Concrete-Filled Steel Bridge Piers

2012 ◽  
Vol 256-259 ◽  
pp. 1640-1647
Author(s):  
Dong Sheng Zhu ◽  
Biao Pang
Keyword(s):  
Large Scale ◽  
Axial Strain ◽  
Constitutive Models ◽  
Steel Tube ◽  
Hysteretic Behavior ◽  
Bridge Piers ◽  
Steel Bridge ◽  
Skeleton Curve ◽  
Cyclic Lateral Load ◽  
Force Displacement

The seismic behavior of concrete-filled circular steel bridge piers was studied by testing four large scale models which were subjected to a constant axial load in addition to a cyclic lateral load. It was found that concrete-filled circular steel bridge piers had high ductility and energy dissipation capacity. Based on the hysteretic force-displacement, the hysteretic behavior of strength reduction was analyzed. Based on the axial strain and the circumferential strain, the plastic area and the strain feature of steel tube were analyzed. According to two different constitutive models of concrete-filled steel tube, the skeleton curve of moment-curvature and force-displacement were calculated and compared with testing data.

Simplified Elastic-Plastic Analysis Method Using Ke Factors Obtained for the Real Structural Model

2003 ◽  
Vol 125 (1) ◽  
pp. 59-64 ◽  
Author(s):  
Asao Okamoto ◽  
Yasuhiro Ohtake
Keyword(s):  
Evaluation Method ◽  
Structural Model ◽  
Practical Case ◽  
Analysis Method ◽  
Axisymmetric Nozzle ◽  
Element Analysis ◽  
The Real ◽  
Elastic Plastic ◽  
Wide Range ◽  
Plastic Analysis

This paper describes a new simplified elastic-plastic analysis method, which utilizes a plastic strain multiplication factor (Ke factor) obtained from elastic-plastic finite element analysis (FEA) results for the same structural model in the design stress calculation. ASME Code, Sec. III specifies a simplified elastic-plastic analysis method which can be used when PL+Q intensity exceeds the 3Sm limit, provided that the rules to prevent thermal stress ratchet are satisfied. The conventional method requires using Ke factors given by a closed-form equation having a value of PL+Q intensity as a variable. The elastically calculated peak stresses need be multiplied by the Ke factors, before performing the fatigue analysis. The Ke factors in the Code were derived from strain multiplication factors calculated for rather simple structural elements, which are assumed to cover a wide range of structural components. Consequently, although the rule can be applied safely to most of the cases, the results are usually too conservative. On the other hand, when PL+Q intensities are near 3Sm level, it has been pointed out based on experiments and analyses that the current Ke has a lack of margin. We propose to use the Ke factors obtained by FEA of the real structural model, in order to avoid the foregoing overconservatism and the lack of margin. The procedure also makes it unnecessary to extract PL+Q category, which is necessary in the conventional evaluation method. Elastic and elastic-plastic FEAs were performed for the axisymmetric nozzle in a vessel, and the effectiveness of the proposed procedure was shown in a practical case. Generalization of the procedure is also discussed.

scholarly journals Covering complete proteomes with X-ray structures: a current snapshot

2014 ◽  
Vol 70 (11) ◽  
pp. 2781-2793 ◽  
Author(s):  
Marcin J. Mizianty ◽  
Xiao Fan ◽  
Jing Yan ◽  
Eric Chalmers ◽  
Christopher Woloschuk ◽  
...  
Keyword(s):  
Homology Modeling ◽  
Structure Determination ◽  
Large Scale ◽  
Structural Model ◽  
Target Selection ◽  
Three Dimensional ◽  
X Ray ◽  
X Ray Crystallography ◽  
Knowledge Based ◽  
Wide Range

Structural genomics programs have developed and applied structure-determination pipelines to a wide range of protein targets, facilitating the visualization of macromolecular interactions and the understanding of their molecular and biochemical functions. The fundamental question of whether three-dimensional structures of all proteins and all functional annotations can be determined using X-ray crystallography is investigated. A first-of-its-kind large-scale analysis of crystallization propensity for all proteins encoded in 1953 fully sequenced genomes was performed. It is shown that current X-ray crystallographic knowhow combined with homology modeling can provide structures for 25% of modeling families (protein clusters for which structural models can be obtained through homology modeling), with at least one structural model produced for each Gene Ontology functional annotation. The coverage varies between superkingdoms, with 19% for eukaryotes, 35% for bacteria and 49% for archaea, and with those of viruses following the coverage values of their hosts. It is shown that the crystallization propensities of proteomes from the taxonomic superkingdoms are distinct. The use of knowledge-based target selection is shown to substantially increase the ability to produce X-ray structures. It is demonstrated that the human proteome has one of the highest attainable coverage values among eukaryotes, and GPCR membrane proteins suitable for X-ray structure determination were determined.

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