Academic literature on the topic '3d nonlinear models'
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Journal articles on the topic "3d nonlinear models"
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Kurths, J., A. Brandenburg, U. Feudel, and W. Jansen. "Chaos in Nonlinear Dynamo Models." Symposium - International Astronomical Union 157 (1993): 83–89. http://dx.doi.org/10.1017/s0074180900173917.
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Two nonlinear dynamos have been analyzed by numerical means: 3D-simulation of the magneto-hydrodynamic equations and qualitative analysis of a simplified low-dimensional mean field model. It turns out that both are capable of deterministic chaos in a certain parameter range. As the basic tool the calculation of Lyapunov exponents has been used.
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Pupure, Liva, Leonids Pakrastins, and Janis Varna. "Challenges in developing of 3D nonlinear viscoelastic models." IOP Conference Series: Materials Science and Engineering 1190, no. 1 (October 1, 2021): 012005. http://dx.doi.org/10.1088/1757-899x/1190/1/012005.
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Davids, William G., and George M. Turkiyyah. "Multigrid Preconditioner for Unstructured Nonlinear 3D FE Models." Journal of Engineering Mechanics 125, no. 2 (February 1999): 186–96. http://dx.doi.org/10.1061/(asce)0733-9399(1999)125:2(186).
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Zakrzewski, Kazimierz, Bronisław Tomczuk, and Andrzej Waindok. "Nonlinear scaled models in 3D calculation of transformer magnetic circuits." COMPEL - The international journal for computation and mathematics in electrical and electronic engineering 25, no. 1 (January 2006): 91–101. http://dx.doi.org/10.1108/03321640610634362.
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Kou, X. Y., S. T. Tan, and Hod Lipson. "A Data-Driven Process for Estimating Nonlinear Material Models." Applied Mechanics and Materials 50-51 (February 2011): 599–604. http://dx.doi.org/10.4028/www.scientific.net/amm.50-51.599.
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Driven by the wide range of new material properties offered by multi-material 3D printing, there is emerging need to create predictive material models for these materials. A data driven process for estimating nonlinear material model is presented in this paper. In contrast with classical methods which derive the engineering stress-strain relationship assuming constant cross-section area and fixed length of a specimen, the proposed approach takes full advantage of 3D geometry of the specimen to estimate the material models. Give a hypothetical material model, virtual tensile tests are performed using Finite Element Analysis (FEA) method, and the parameters of the material model are estimated by minimizing the discrepancies of the virtual responses and the experimental results. The detailed material models, numerical algorithms as well as the optimization approaches are presented and finally preliminary results are offered.
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Makeeva, G. S., and O. A. Golovanov. "Mathematical Models of Microwave and Photonic Devices Engaging Strong Nonlinearities Using Decomposition on Nonlinear Autonomous Blocks." WSEAS TRANSACTIONS ON COMMUNICATIONS 20 (March 17, 2021): 44–51. http://dx.doi.org/10.37394/23204.2021.20.6.
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Mathematical modeling technique based on solving the nonlinear Maxwell’s equations (Eqs.) rigorously using the decomposition approach on nonlinear autonomous blocks partially filled by the nonlinear media with a “strong” nonlinearity (NABs) and reliable engineering method for numerical computation of microwave and photonic nonlinear 3D devices engaging strong nonlinearities, applicable in CAD, were developed. To determine the NAB descriptors the iterative computational process for solving the nonlinear 3D diffraction boundary problems with the non-asymptotic radiation boundary conditions on the NAB bounds was performed using the projection method. The iteration method of recomposition of NABs is developed using the linearization of its descriptors. Using the computational algorithm for solving nonlinear diffraction boundary problems performed as NABs and improved computation algorithm of determination of bifurcation points the nonlinearity thresholds in the magnetic nanoarrays at microwaves were numerically simulated.
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Jiang, Huan Jun, and Lao Er Liu. "Numerical Analysis of RC Shear Walls under Cyclic Loading by PERFORM-3D." Advanced Materials Research 250-253 (May 2011): 2253–57. http://dx.doi.org/10.4028/www.scientific.net/amr.250-253.2253.
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For engineering practice purpose, the macroscopic model capable of simulating the main characteristics of nonlinear behavior is desirable to reduce computational efforts in nonlinear structural analysis. Several different types of macroscopic models for shear walls have been developed. The shear wall element used in the commercial program PERFORM-3D is one types of macroscopic models for reinforced concrete shear walls. The application of PERFORM-3D in the nonlinear static analysis of reinforced concrete shear walls is introduced in this study. The selection of constitutive models and the determination of related parameters of the constituent material are presented in detail. The applicability of the shear wall element is verified by numerical simulation on three reinforced concrete shear wall specimens under cyclic loading. The comparison between the numerical analysis and test results leads to the conclusion that the shear wall element with appropriate constitutive models can capture the nonlinear behavior of reinforced concrete shear wall well and be conveniently applied in engineering practice.
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Saldívar, Mauricio Cruz, Eugeni L. Doubrovski, Mohammad J. Mirzaali, and Amir A. Zadpoor. "Nonlinear coarse-graining models for 3D printed multi-material biomimetic composites." Additive Manufacturing 58 (October 2022): 103062. http://dx.doi.org/10.1016/j.addma.2022.103062.
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Mahfouz, Mohamed, Ahmed Badawi, Brandon Merkl, Emam E. Abdel Fatah, Emily Pritchard, Katherine Kesler, Megan Moore, Richard Jantz, and Lee Jantz. "Patella sex determination by 3D statistical shape models and nonlinear classifiers." Forensic Science International 173, no. 2-3 (December 2007): 161–70. http://dx.doi.org/10.1016/j.forsciint.2007.02.024.
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Zhao, Yong. "Finite Element Modeling and Analysis of Nonlinear Impact and Frictional Motion Responses Including Fluid—Structure Coupling Effects." Shock and Vibration 4, no. 5-6 (1997): 311–25. http://dx.doi.org/10.1155/1997/496945.
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A nonlinear three dimensional (3D) single rack model and a nonlinear 3D whole pool multi-rack model are developed for the spent fuel storage racks of a nuclear power plant (NPP) to determine impacts and frictional motion responses when subjected to 3D excitations from the supporting building floor. The submerged free standing rack system and surrounding water are coupled due to hydrodynamic fluid-structure interaction (FSI) using potential theory. The models developed have features that allow consideration of geometric and material nonlinearities including (1) the impacts of fuel assemblies to rack cells, a rack to adjacent racks or pool walls, and rack support legs to the pool floor; (2) the hydrodynamic coupling of fuel assemblies with their storing racks, and of a rack with adjacent racks, pool walls, and the pool floor; and (3) the dynamic motion behavior of rocking, twisting, and frictional sliding of rack modules. Using these models 3D nonlinear time history dynamic analyses are performed per the U.S. Nuclear Regulatory Commission (USNRC) criteria. Since few such modeling, analyses, and results using both the 3D single and whole pool multiple rack models are available in the literature, this paper emphasizes description of modeling and analysis techniques using the SOLVIA general purpose nonlinear finite element code. Typical response results with different Coulomb friction coefficients are presented and discussed.
Dissertations / Theses on the topic "3d nonlinear models"
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Reichert, Thomas. "Development of 3D lattice models for predicting nonlinear timber joint behaviour." Thesis, Edinburgh Napier University, 2009. http://researchrepository.napier.ac.uk/Output/2827.
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This work presents the development of a three-dimensional lattice material model for wood and its application to timber joints including the potential strengthening benefit of second order effects. A lattice of discrete elements was used to capture the heterogeneity and fracture behaviour and the model results compared to tested Sitka spruce (Picea sitchensis) specimens. Despite the general applicability of lattice models to timber, they are computationally demanding, due to the nonlinear solution and large number of degrees of freedom required. Ways to reduce the computational costs are investigated. Timber joints fail due to plastic deformation of the steel fastener(s), embedment, or brittle fracture of the timber. Lattice models, contrary to other modelling approaches such as continuum finite elements, have the advantage to take into account brittle fracture, crack development and material heterogeneity by assigning certain strength and stiffness properties to individual elements. Furthermore, plastic hardening is considered to simulate timber embedment. The lattice is an arrangement of longitudinal, lateral and diagonal link elements with a tri-linear load-displacement relation. The lattice is used in areas with high stress gradients and normal continuum elements are used elsewhere. Heterogeneity was accounted for by creating an artificial growth ring structure and density profile upon which the mean strength and stiffness properties were adjusted. Solution algorithms, such as Newton-Raphson, encounter problems with discrete elements for which 'snap-back' in the global load-displacement curves would occur. Thus, a specialised solution algorithm, developed by Jirasek and Bazant, was adopted to create a bespoke FE code in MATLAB that can handle the jagged behaviour of the load displacement response, and extended to account for plastic deformation. The model's input parameters were calibrated by determining the elastic stiffness from literature values and adjusting the strength, post-yield and heterogeneity parameters of lattice elements to match the load-displacement from laboratory tests under various loading conditions. Although problems with the modified solution algorithm were encountered, results of the model show the potential of lattice models to be used as a tool to predict load-displacement curves and fracture patterns of timber specimens.
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MARZIANI, ROBERTA. "Asymptotic analysis of nonlinear models for line defects in materials." Doctoral thesis, Gran Sasso Science Institute, 2020. http://hdl.handle.net/20.500.12571/10041.
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The thesis is devoted to the study of the elastic behavior of solid crystals in the presence of dislocation defects by a variational point of view. In the first part we consider a Geometrically nonlinear elastic model in the three-dimensional setting, that allows for large rotations. Adopting a core approach, which consists in regularizing the problem at scale epsilon>0 around the dislocation lines, we perform the asymptotic analysis of the regularized energy as epsilon tends to 0. We focus in particular on the leading order regime and prove that the energy rescaled by $eps^2|logeps|$ Gamma converges to the line-tension for a dislocation density derived by Conti, Garroni and Ortiz in a three-dimensional linear framework.
The analysis is performed under the assumption that the dislocations are well separated at intermediate scale, this in fact will allow to treat individually each dislocation by means of a suitable cell formula.
The nonlinear nature of the energy requires that in the characterization of the cell formula we take into account that the deformation gradient is close to a fixed rotation.
In the second part we obtain the same Gamma-limit but starting from a nonlinear elastic model with mixed growth, that is we consider an elastic energy which is substantially quadratic far from the dislocations and sub-quadratic in the core region. This can be seen as another way of regularising the problem and allow us to slightly relax the diluteness condition of the admissible dislocation density and improve the compactness result obtained in the previous case.
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Citipitioglu, Ahmet Muhtar. "Development and assessment of response and strength models for bolted steel connections using refined nonlinear 3D finite element analysis." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/31691.
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Thesis (Ph.D)--Civil and Environmental Engineering, Georgia Institute of Technology, 2010.Committee Chair: Haj-Ali, Rami; Committee Co-Chair: Leon, Roberto; Committee Co-Chair: White, Donald; Committee Member: DesRoches, Reginald; Committee Member: Gentry, Russell. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Lorenz, Haik. "Texturierung und Visualisierung virtueller 3D-Stadtmodelle." Phd thesis, Universität Potsdam, 2011. http://opus.kobv.de/ubp/volltexte/2011/5387/.
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Im Mittelpunkt dieser Arbeit stehen virtuelle 3D-Stadtmodelle, die Objekte, Phänomene und Prozesse in urbanen Räumen in digitaler Form repräsentieren. Sie haben sich zu einem Kernthema von Geoinformationssystemen entwickelt und bilden einen zentralen Bestandteil geovirtueller 3D-Welten. Virtuelle 3D-Stadtmodelle finden nicht nur Verwendung als Mittel für Experten in Bereichen wie Stadtplanung, Funknetzplanung, oder Lärmanalyse, sondern auch für allgemeine Nutzer, die realitätsnah dargestellte virtuelle Städte in Bereichen wie Bürgerbeteiligung, Tourismus oder Unterhaltung nutzen und z. B. in Anwendungen wie GoogleEarth eine räumliche Umgebung intuitiv erkunden und durch eigene 3D-Modelle oder zusätzliche Informationen erweitern.
Die Erzeugung und Darstellung virtueller 3D-Stadtmodelle besteht aus einer Vielzahl von Prozessschritten, von denen in der vorliegenden Arbeit zwei näher betrachtet werden: Texturierung und Visualisierung. Im Bereich der Texturierung werden Konzepte und Verfahren zur automatischen Ableitung von Fototexturen aus georeferenzierten Schrägluftbildern sowie zur Speicherung oberflächengebundener Daten in virtuellen 3D-Stadtmodellen entwickelt. Im Bereich der Visualisierung werden Konzepte und Verfahren für die multiperspektivische Darstellung sowie für die hochqualitative Darstellung nichtlinearer Projektionen virtueller 3D-Stadtmodelle in interaktiven Systemen vorgestellt.
Die automatische Ableitung von Fototexturen aus georeferenzierten Schrägluftbildern ermöglicht die Veredelung vorliegender virtueller 3D-Stadtmodelle. Schrägluftbilder bieten sich zur Texturierung an, da sie einen Großteil der Oberflächen einer Stadt, insbesondere Gebäudefassaden, mit hoher Redundanz erfassen. Das Verfahren extrahiert aus dem verfügbaren Bildmaterial alle Ansichten einer Oberfläche und fügt diese pixelpräzise zu einer Textur zusammen. Durch Anwendung auf alle Oberflächen wird das virtuelle 3D-Stadtmodell flächendeckend texturiert. Der beschriebene Ansatz wurde am Beispiel des offiziellen Berliner 3D-Stadtmodells sowie der in GoogleEarth integrierten Innenstadt von München erprobt.
Die Speicherung oberflächengebundener Daten, zu denen auch Texturen zählen, wurde im Kontext von CityGML, einem international standardisierten Datenmodell und Austauschformat für virtuelle 3D-Stadtmodelle, untersucht. Es wird ein Datenmodell auf Basis computergrafischer Konzepte entworfen und in den CityGML-Standard integriert. Dieses Datenmodell richtet sich dabei an praktischen Anwendungsfällen aus und lässt sich domänenübergreifend verwenden.
Die interaktive multiperspektivische Darstellung virtueller 3D-Stadtmodelle ergänzt die gewohnte perspektivische Darstellung nahtlos um eine zweite Perspektive mit dem Ziel, den Informationsgehalt der Darstellung zu erhöhen. Diese Art der Darstellung ist durch die Panoramakarten von H. C. Berann inspiriert; Hauptproblem ist die Übertragung des multiperspektivischen Prinzips auf ein interaktives System. Die Arbeit stellt eine technische Umsetzung dieser Darstellung für 3D-Grafikhardware vor und demonstriert die Erweiterung von Vogel- und Fußgängerperspektive.
Die hochqualitative Darstellung nichtlinearer Projektionen beschreibt deren Umsetzung auf 3D-Grafikhardware, wobei neben der Bildwiederholrate die Bildqualität das wesentliche Entwicklungskriterium ist. Insbesondere erlauben die beiden vorgestellten Verfahren, dynamische Geometrieverfeinerung und stückweise perspektivische Projektionen, die uneingeschränkte Nutzung aller hardwareseitig verfügbaren, qualitätssteigernden Funktionen wie z.~B. Bildraumgradienten oder anisotroper Texturfilterung. Beide Verfahren sind generisch und unterstützen verschiedene Projektionstypen. Sie ermöglichen die anpassungsfreie Verwendung gängiger computergrafischer Effekte wie Stilisierungsverfahren oder prozeduraler Texturen für nichtlineare Projektionen bei optimaler Bildqualität.
Die vorliegende Arbeit beschreibt wesentliche Technologien für die Verarbeitung virtueller 3D-Stadtmodelle: Zum einen lassen sich mit den Ergebnissen der Arbeit Texturen für virtuelle 3D-Stadtmodelle automatisiert herstellen und als eigenständige Attribute in das virtuelle 3D-Stadtmodell einfügen. Somit trägt diese Arbeit dazu bei, die Herstellung und Fortführung texturierter virtueller 3D-Stadtmodelle zu verbessern. Zum anderen zeigt die Arbeit Varianten und technische Lösungen für neuartige Projektionstypen für virtueller 3D-Stadtmodelle in interaktiven Visualisierungen. Solche nichtlinearen Projektionen stellen Schlüsselbausteine dar, um neuartige Benutzungsschnittstellen für und Interaktionsformen mit virtuellen 3D-Stadtmodellen zu ermöglichen, insbesondere für mobile Geräte und immersive Umgebungen.This thesis concentrates on virtual 3D city models that digitally encode objects, phenomena, and processes in urban environments. Such models have become core elements of geographic information systems and constitute a major component of geovirtual 3D worlds. Expert users make use of virtual 3D city models in various application domains, such as urban planning, radio-network planning, and noise immision simulation. Regular users utilize virtual 3D city models in domains, such as tourism, and entertainment. They intuitively explore photorealistic virtual 3D city models through mainstream applications such as GoogleEarth, which additionally enable users to extend virtual 3D city models by custom 3D models and supplemental information. Creation and rendering of virtual 3D city models comprise a large number of processes, from which texturing and visualization are in the focus of this thesis. In the area of texturing, this thesis presents concepts and techniques for automatic derivation of photo textures from georeferenced oblique aerial imagery and a concept for the integration of surface-bound data into virtual 3D city model datasets. In the area of visualization, this thesis presents concepts and techniques for multiperspective views and for high-quality rendering of nonlinearly projected virtual 3D city models in interactive systems. The automatic derivation of photo textures from georeferenced oblique aerial imagery is a refinement process for a given virtual 3D city model. Our approach uses oblique aerial imagery, since it provides a citywide highly redundant coverage of surfaces, particularly building facades. From this imagery, our approach extracts all views of a given surface and creates a photo texture by selecting the best view on a pixel level. By processing all surfaces, the virtual 3D city model becomes completely textured. This approach has been tested for the official 3D city model of Berlin and the model of the inner city of Munich accessible in GoogleEarth. The integration of surface-bound data, which include textures, into virtual 3D city model datasets has been performed in the context of CityGML, an international standard for the exchange and storage of virtual 3D city models. We derive a data model from a set of use cases and integrate it into the CityGML standard. The data model uses well-known concepts from computer graphics for data representation. Interactive multiperspective views of virtual 3D city models seamlessly supplement a regular perspective view with a second perspective. Such a construction is inspired by panorama maps by H. C. Berann and aims at increasing the amount of information in the image. Key aspect is the construction's use in an interactive system. This thesis presents an approach to create multiperspective views on 3D graphics hardware and exemplifies the extension of bird's eye and pedestrian views. High-quality rendering of nonlinearly projected virtual 3D city models focuses on the implementation of nonlinear projections on 3D graphics hardware. The developed concepts and techniques focus on high image quality. This thesis presents two such concepts, namely dynamic mesh refinement and piecewise perspective projections, which both enable the use of all graphics hardware features, such as screen space gradients and anisotropic texture filtering under nonlinear projections. Both concepts are generic and customizable towards specific projections. They enable the use of common computer graphics effects, such as stylization effects or procedural textures, for nonlinear projections at optimal image quality and interactive frame rates. This thesis comprises essential techniques for virtual 3D city model processing. First, the results of this thesis enable automated creation of textures for and their integration as individual attributes into virtual 3D city models. Hence, this thesis contributes to an improved creation and continuation of textured virtual 3D city models. Furthermore, the results provide novel approaches to and technical solutions for projecting virtual 3D city models in interactive visualizations. Such nonlinear projections are key components of novel user interfaces and interaction techniques for virtual 3D city models, particularly on mobile devices and in immersive environments.
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Hong, Jung-Pyo. "Three-dimensional nonlinear finite element model for single and multiple dowel-type wood connections." Thesis, University of British Columbia, 2007. http://hdl.handle.net/2429/364.
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A new three-dimensional finite solid element (3D FE) model for dowel-type wood connections was developed using the concept of a beam on a nonlinear wood foundation, which addresses the intricate wood crushing behaviour under the connector in a dowel type connection.
In order to implement the concept of wood foundation with solid elements, a 3D FE wood foundation model was defined within a prescribed foundation zone surrounding the dowel. Based on anisotropic plasticity material theory, the material model for the foundation zone was developed using effective foundation material constants that were defined from dowel-embedment test data.
New 3D FE single nail connection models were developed that incorporated the wood foundation model. The 3D wood foundation model was justified and validated using dowel-embedment test data with a range of dowel diameters, from a 2.5-mm nail to a25.4-mm bolt. The connection models provided successful results in simulating the characteristics of load-slip behaviour that were experimentally observed.
Based on the success of the single nail connection models, several applications of the3D FE connection models were investigated including statistical wood material models, bolted connection models and a multiple nail connection model. Throughout the application studies, discussion of the benefits and limitations of the new model approach using the 3D FE wood foundation are presented. Also, future areas of study are proposed in order to improve the 3D FE dowel-type wood connections models.
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Carloni, Federico. "A 3D model based on the SAM Method for seismic studies of masonry buildings." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018. http://amslaurea.unibo.it/17151/.
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L'elaborato propone un metodo per la modellazione tridimensionale di interi edifici in muratura, con lo scopo di valutare le performance sismiche, mediante il programma di calcolo SAP2000. La metodologia proposta consente la modellazione di pareti in muratura simulandone il comportamento non lineare sotto azioni agenti nel piano ed allo stesso tempo permette di considerare la ripartizione delle azioni verticali e soprattutto orizzontali che avviene tra le pareti, dovuta alle zone di connessione, ai solai ed alla loro rigidezza a taglio nel piano. Per lo sviluppo del metodo di modellazione è stato utilizzato un edificio molto semplice. Successivamente la metodologia è stata applicata ad un caso più realistico sul quale si sono fatte anche considerazioni riguardo i diversi comportamenti della struttura in funzione della rigidezza dei solai.
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Xia, Liang. "Towards optimal design of multiscale nonlinear structures : reduced-order modeling approaches." Thesis, Compiègne, 2015. http://www.theses.fr/2015COMP2230/document.
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L'objectif principal est de faire premiers pas vers la conception topologique de structures hétérogènes à comportement non-linéaires. Le deuxième objectif est d’optimiser simultanément la topologie de la structure et du matériau. Il requiert la combinaison des méthodes de conception optimale et des approches de modélisation multi-échelle. En raison des lourdes exigences de calcul, nous avons introduit des techniques de réduction de modèle et de calcul parallèle. Nous avons développé tout d’abord un cadre de conception multi-échelle constitué de l’optimisation topologique et la modélisation multi-échelle. Ce cadre fournit un outil automatique pour des structures dont le modèle de matériau sous-jacent est directement régi par la géométrie de la microstructure réaliste et des lois de comportement microscopiques. Nous avons ensuite étendu le cadre en introduisant des variables supplémentaires à l’échelle microscopique pour effectuer la conception simultanée de la structure et de la microstructure. En ce qui concerne les exigences de calcul et de stockage de données en raison de multiples réalisations de calcul multi-échelle sur les configurations similaires, nous avons introduit: les approches de réduction de modèle. Nous avons développé un substitut d'apprentissage adaptatif pour le cas de l’élasticité non-linéaire. Pour viscoplasticité, nous avons collaboré avec le Professeur Felix Fritzen de l’Université de Stuttgart en utilisant son modèle de réduction avec la programmation parallèle sur GPU. Nous avons également adopté une autre approche basée sur le potentiel de réduction issue de la littérature pour améliorer l’efficacité de la conception simultanéeHigh-performance heterogeneous materials have been increasingly used nowadays for their advantageous overall characteristics resulting in superior structural mechanical performance. The pronounced heterogeneities of materials have significant impact on the structural behavior that one needs to account for both material microscopic heterogeneities and constituent behaviors to achieve reliable structural designs. Meanwhile, the fast progress of material science and the latest development of 3D printing techniques make it possible to generate more innovative, lightweight, and structurally efficient designs through controlling the composition and the microstructure of material at the microscopic scale. In this thesis, we have made first attempts towards topology optimization design of multiscale nonlinear structures, including design of highly heterogeneous structures, material microstructural design, and simultaneous design of structure and materials. We have primarily developed a multiscale design framework, constituted of two key ingredients : multiscale modeling for structural performance simulation and topology optimization forstructural design. With regard to the first ingredient, we employ the first-order computational homogenization method FE2 to bridge structural and material scales. With regard to the second ingredient, we apply the method Bi-directional Evolutionary Structural Optimization (BESO) to perform topology optimization. In contrast to the conventional nonlinear design of homogeneous structures, this design framework provides an automatic design tool for nonlinear highly heterogeneous structures of which the underlying material model is governed directly by the realistic microstructural geometry and the microscopic constitutive laws. Note that the FE2 method is extremely expensive in terms of computing time and storage requirement. The dilemma of heavy computational burden is even more pronounced when it comes to topology optimization : not only is it required to solve the time-consuming multiscale problem once, but for many different realizations of the structural topology. Meanwhile we note that the optimization process requires multiple design loops involving similar or even repeated computations at the microscopic scale. For these reasons, we introduce to the design framework a third ingredient : reduced-order modeling (ROM). We develop an adaptive surrogate model using snapshot Proper Orthogonal Decomposition (POD) and Diffuse Approximation to substitute the microscopic solutions. The surrogate model is initially built by the first design iteration and updated adaptively in the subsequent design iterations. This surrogate model has shown promising performance in terms of reducing computing cost and modeling accuracy when applied to the design framework for nonlinear elastic cases. As for more severe material nonlinearity, we employ directly an established method potential based Reduced Basis Model Order Reduction (pRBMOR). The key idea of pRBMOR is to approximate the internal variables of the dissipative material by a precomputed reduced basis computed from snapshot POD. To drastically accelerate the computing procedure, pRBMOR has been implemented by parallelization on modern Graphics Processing Units (GPUs). The implementation of pRBMOR with GPU acceleration enables us to realize the design of multiscale elastoviscoplastic structures using the previously developed design framework inrealistic computing time and with affordable memory requirement. We have so far assumed a fixed material microstructure at the microscopic scale. The remaining part of the thesis is dedicated to simultaneous design of both macroscopic structure and microscopic materials. By the previously established multiscale design framework, we have topology variables and volume constraints defined at both scales
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Wei, Sicong. "A 3D Sliding Bearing Finite Element Based on The Bouc-Wen Hysteretic Model : Mathematical modelling and numerical implementation." Thesis, KTH, Bro- och stålbyggnad, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-289480.
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Bridge bearing is an essential component with the function of connecting the superstructure and substructure of the bridge, transmitting load and providing movability to the superstructure. Under dynamic conditions, the internal friction of bridge bearing dissipates the vibration energy and therefore reduces the dynamic response of the bridge. Meanwhile, bearing friction is considered to have possible contribution to some nonlinear dynamic behaviour of the bridge structure, which requires further investigation.However, bearing friction, in most cases, are ignored or considered roughly and implicitly as part of structural damping in current bridge designing codes and methods. Most previous research was also focusing on bearing friction’s effect under high-amplitude vibration conditions, such as earthquake or heavy wind load. Bearing friction’s effect under common low-amplitude vibration in SLS such as train-induced vibration and vehicle-induced vibration is less attended. Although the effect of such low-amplitude vibration is less significant to structural safety, it plays an essential role to the bridge’s traffic safety and comfort. Meanwhile, the cumulative effect of such vibration can significantly influence the life and durability of bridge bearings due to its high occurring frequency. Hence, a clearer understanding of bearing dynamic behaviour is required to improve the understanding of bridge and bearing dynamics.In this thesis, an advanced numerical tool is developed for dynamic analysis of bearing friction. A 3D pot bearing finite element that can be implemented in commercial FE software ABAQUS, is programmed based on the mathematical friction models developed in previous research and the Bouc-Wen hysteretic model. Numerical results that accord with the results of relevant friction tests are produced by the calibrated and validated bearing finite element, giving proof that the element is capable to reflect the dynamic friction response of bridge pot bearing in reality.The 3D shell numerical model of Banafjäl bridge located on the Bothnia Line in Norrland, Sweden, is built as a study case of bridge dynamic analysis in this thesis, with implementation of the newly developed bearing element. The feasibility of implementing the bearing element in bridge dynamic analysis is proven by the numerical results. The nonlinear influence of bearing friction on the dynamic response of bridge structure, especially the influence on structural damping properties, is discussed preliminarily. The analysis results show that with the consideration of bearing friction, the damping presents a clear amplitude-dependency, which accords the phenomenon reported in previous research.
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Guney, Murat Efe. "A Numerical Procedure For The Nonlinear Analysis Of Reinforced Concrete Frames With Infill Walls." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/12606318/index.pdf.
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Materially non-linear analysis of reinforced concrete frame structures with infill walls requires appropriate mathematical models to be adopted for the beams and the columns as well as the infill walls. This study presents a mathematical model for frame elements based on a 3D Hermitian beam/column finite element and an equivalent strut model for the infill walls. The spread-of-plasticity approach is employed to model the material nonlinearity of the frame elements. The cross-section of the frame element is divided into triangular sub regions to evaluate the stiffness properties and the response of the element cross-section. By the help of the triangles spread over the actual area of the section, the bi-axial bending and the axial deformations are coupled in the inelastic range. A frame super-element is also formed by combining a number of frame finite elements.
Two identical compression-only diagonal struts are used for modeling the infill. The equivalent geometric and material properties of the struts are determined from the geometry of the infill and the strength of the masonry units
A computer code is developed using the object-oriented design paradigm and the models are implemented into this code. Efficiency and the effectiveness of the models are investigated for various cases by comparing the numerical response predictions produced by the program with those obtained from experimental studies.
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GAZZANI, VALENTINA. "Influence of FE Modelling on Typical and Specific Vulnerabilities of RC School Buildings." Doctoral thesis, Università Politecnica delle Marche, 2019. http://hdl.handle.net/11566/263653.
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La valutazione della vulnerabilità degli edifici scolastici esistenti nei confronti dei terremoti è un’esigenza di primaria importanza per la società in Italia.
Poiché, generalmente, strutture dello stesso tipo e medesimo periodo di costruzione presentano caratteristiche simili, è stato possibile evidenziare le vulnerabilità tipiche e specifiche per differenti layout architettonici individuabili in scuole dell’infanzia, primarie e secondarie di I grado.
Inizialmente, per una stima rapida delle prestazioni degli edifici, è stata valutata la vulnerabilità sismica di ciascun edificio scolastico ubicato nel comune di Trecastelli, adottando modelli ad aste a plasticità concentrata ed analisi statiche non lineari.
Successivamente, per quantificare l'effettiva influenza delle vulnerabilità rilevate sul comportamento globale, è stato scelto un edificio scolastico in c.a. e realizzati tre modelli corrispondenti ad altrettanti approcci di modellazione affetti da diverse limitazioni di rappresentazione dei fenomeni reali.
Per tale scopo, sono stati impiegati approcci a plasticità concentrata, a plasticità diffusa (modellazione a fibre) e al continuo con elementi solidi.
Il confronto dei risultati numerici ottenuti da analisi pushover ha mostrato l’inadeguatezza del modello a fibre nella rappresentazione dei problemi di taglio del caso studio.
Diversamente, il modello a plasticità concentrata si è rivelato più aderente alla realtà di quello a fibre ma non abbastanza preciso da considerare sollecitazioni concomitanti di flessione, taglio e sforzo normale e l'interazione tra di esse nella risposta inelastica della struttura.
Naturalmente, il modello realizzato con elementi solidi 3D per il calcestruzzo e 1D per l’armatura risulta molto più accurato nella descrizione dei meccanismi complessi e combinati che si sviluppano nei nodi.
Infine, è stata valutata anche l'efficacia di un possibile intervento di rinforzo tramite CFRP limitandosi al confinamento dei nodi non confinati.The vulnerability assessment of existing school buildings against earthquakes represents a priority concern for the society in seismic countries. Since structures belonging to the same type and construction period may share similar features, it was possible to point out typical and specific seismic vulnerabilities related to different school architectural layouts for buildings that host the lower levels of the Italian education system. Firstly, to estimate the performance of buildings in a fast way, the vulnerability of each school building belonging to the municipality of Trecastelli was assessed, adopting a lumped plasticity approach and a nonlinear static procedure. With the aim of quantifying the effective influence of these vulnerabilities detected on the global seismic behaviour, a RC school building was chosen and three different models were implemented correspond to as many different approaches affected by various limitations in the representativeness respect to the reality. The different modelling technique used follow the lumped plasticity, the distributed plasticity (fibre model) and the 3D Continuum FE approaches. Nonlinear static (pushover) analyses were performed to assess the global seismic behaviour of the structure. The comparison of the numerical results has shown that the fibre model is the least suitable mean to represent the shear problems of the case study. Instead, the lumped plasticity model is closer to reality than the previous one but not precise enough to consider the concomitance of bending, shear and axial force and the interaction between them in the inelastic response. Of course, the 3D Continuum model is much more accurate than other models to describe the mechanisms developed in the joint panels which are very complex and combined. Finally, the effectiveness of a possible CFRP local strengthening intervention for the case study limited to confine the unconfined beam-column joints was also considered.
Book chapters on the topic "3d nonlinear models"
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Grafarend, Erik W., and Joseph L. Awange. "The Nonlinear Problem of the 3d Datum Transformation and the Procrustes Algorithm." In Linear and Nonlinear Models, 461–75. Berlin, Heidelberg: Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-22241-2_12.
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Brenier, Yann. "A Note on Deformations of 2D Fluid Motions Using 3D Born-Infeld Equations." In Nonlinear Differential Equation Models, 113–22. Vienna: Springer Vienna, 2004. http://dx.doi.org/10.1007/978-3-7091-0609-9_9.
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Grafarend, Erik, Silvelyn Zwanzig, and Joseph Awange. "The Nonlinear Problem of the 3d Datum Transformation and the Procrustes Algorithm." In Applications of Linear and Nonlinear Models, 467–81. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-94598-5_12.
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Sarti, A., K. Mikula, F. Sgallari, and C. Lamberti. "Nonlinear Multiscale Analysis Models for Filtering of 3D + Time Biomedical Images." In Mathematics and Visualization, 107–27. Berlin, Heidelberg: Springer Berlin Heidelberg, 2002. http://dx.doi.org/10.1007/978-3-642-55987-7_7.
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Freddi, Lorenzo, and Roberto Paroni. "Variational Dimension Reduction in Nonlinear Elasticity: A Young Measure Approach." In IUTAM Symposium on Relations of Shell Plate Beam and 3D Models, 111–22. Dordrecht: Springer Netherlands, 2008. http://dx.doi.org/10.1007/978-1-4020-8774-5_10.
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Meunargia, Tengiz. "A Small-Parameter Method for I. Vekua’s Nonlinear and Nonshallow Shells." In IUTAM Symposium on Relations of Shell Plate Beam and 3D Models, 155–66. Dordrecht: Springer Netherlands, 2008. http://dx.doi.org/10.1007/978-1-4020-8774-5_14.
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Goodair, Daniel. "Existence and Uniqueness of Maximal Solutions to a 3D Navier-Stokes Equation with Stochastic Lie Transport." In Mathematics of Planet Earth, 87–107. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-18988-3_7.
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AbstractWe present here a criterion to conclude that an abstract SPDE possesses a unique maximal strong solution, which we apply to a three dimensional Stochastic Navier-Stokes Equation. Motivated by the work of Kato and Lai we ask that there is a comparable result here in the stochastic case whilst facilitating a variety of noise structures such as additive, multiplicative and transport. In particular our criterion is designed to fit viscous fluid dynamics models with Stochastic Advection by Lie Transport (SALT) as introduced in Holm (Proc R Soc A: Math Phys Eng Sci 471(2176):20140963, 2015). Our application to the Incompressible Navier-Stokes equation matches the existence and uniqueness result of the deterministic theory. This short work summarises the results and announces two papers (Crisan et al., Existence and uniqueness of maximal strong solutions to nonlinear SPDEs with applications to viscous fluid models, in preparation; Crisan and Goodair, Analytical properties of a 3D stochastic Navier-Stokes equation, 2022, in preparation) which give the full details for the abstract well-posedness arguments and application to the Navier-Stokes Equation respectively.
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Razaz, M., and R. A. Lee. "Parallel Implementation of a 3D Nonlinear Restoration Algorithm." In Noblesse Workshop on Non-Linear Model Based Image Analysis, 52–58. London: Springer London, 1998. http://dx.doi.org/10.1007/978-1-4471-1597-7_9.
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Kirschner, Matthias, Meike Becker, and Stefan Wesarg. "3D Active Shape Model Segmentation with Nonlinear Shape Priors." In Lecture Notes in Computer Science, 492–99. Berlin, Heidelberg: Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-23629-7_60.
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Quattromani, G., A. Palermo, F. Pulvirenti, E. Sabbioni, and F. Cheli. "Nonlinear 3D Dynamic Model of an Automotive Dual Mass Flywheel." In Rotating Machinery, Hybrid Test Methods, Vibro-Acoustics & Laser Vibrometry, Volume 8, 131–42. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-54648-3_14.
Full textConference papers on the topic "3d nonlinear models"
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Khorshev, Alexey A., Olga V. Streltsova, Aleksei S. Bondar, and Fedor V. Chmilenko. "Development and Comparison of 3D Nonlinear Electrothermal Models for Induction Heating Problems." In 2021 IEEE Conference of Russian Young Researchers in Electrical and Electronic Engineering (ElConRus). IEEE, 2021. http://dx.doi.org/10.1109/elconrus51938.2021.9396426.
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Moradi, Hamed, Mohammad R. Movahhedy, and Gholamreza Vossoughi. "Linear and Nonlinear Model of Cutting Forces in Peripheral Milling: A Comparison Between 2D and 3D Models." In ASME 2010 International Mechanical Engineering Congress and Exposition. ASMEDC, 2010. http://dx.doi.org/10.1115/imece2010-38641.
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Peripheral milling is extensively used in manufacturing processes, especially in aerospace industry where end mills are used for milling of wing parts and engine components. Knowledge of the cutting forces is the first necessary stage in analysis of the milling process. In this paper, cutting forces are presented for both two and three dimensional models. Instead of the common linear dependency of cutting forces to the cut chip thickness, two nonlinear models are presented. In the first model, cutting forces are considered as a function of chip thickness with a complete third order polynomial. In the second one, the quadratic and constant terms of the third order polynomial are set to zero. Results show about 2–3% and 2–7% maximum error between the linear, first and second nonlinear models, for 2D and 3D models, respectively. According to the simulation results, both the 2D and 3D models with second type of nonlinearity can be effectively used in practice. The advantage of such modelling is its simplicity in nonlinear analysis of the problem based on perturbation techniques.
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Hashemi, A., and A. Shirazi-Adl. "3D Nonlinear Finite Element Analysis of Knee Joint Implants." In ASME 1999 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1999. http://dx.doi.org/10.1115/imece1999-0424.
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Abstract The finite element (FE) method has been used in orthopaedic biomechanics to investigate the fixation role of different design parameters in total knee replacement (TKA). Previous FE model studies used 2D, axisymmetric and 3D models to represent the geometry while neglecting many essential features. They simulated the bone-implant interface as frictionless, perfectly bonded or with idealized Coulomb’s friction model. The model of screws and posts have also been neglected altogether or inadequately considered in these studies. To overcome these limitations, the objective of the present study was set to develop a detailed 3D FE model of the knee bone-implant structure including all the interacting components in an immediate postoperative period without bony ingrowth to predict the micromotion at the bone-implant interface and stress distribution within the bone and the polyethylene insert.
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Tari, Hafez, and Marcelo J. Dapino. "Fast and Globally Convergent Nonlinear System Model for 3D Magnetostrictive Systems." In ASME 2014 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/smasis2014-7714.
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A globally convergent and fully coupled magnetomechanical model for 3D magnetostrictive systems is presented. In magnetostrictive actuators, magnetic field and stress inputs generate magnetic flux density and strain. We refer to models that follow this scheme as direct models (no relation to the direct magnetomechanical effect). In certain design and control situations, inverse models are necessary in which the magnetic field and stress are found from specified magnetic flux density and strains. This inversion typically involves an iterative procedure, which may be prone to convergence issues. An inverse model approach is proposed for arbitrary magnetostrictive materials. The inversion requirement is a continuous and second order differentiable direct model for any chosen magnetostrictive material. The approach is globally convergent, which makes it ideal for use in finite element frameworks. The premise of the proposed iterative system model is to constitute a recursive correction formula based on second order approximations of a novel scalar error function which allows to achieve a faster convergence rate. A continuation approach is then used to achieve global convergence for arbitrary input parameters. To illustrate, Galfenol is chosen as the magnetostrictive material, and analytical derivations of the Jacobian and Hessian matrices are presented. Finally, the computational efficiency of the proposed approach is shown to compare favorably against existing models.
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Ferrant, Pierre, and David Le Touze´. "Fully-Nonlinear Spectral/BEM Solution for Irregular Wave Interactions With a 3D Body." In ASME 2002 21st International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2002. http://dx.doi.org/10.1115/omae2002-28521.
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An original method for simulating the interaction of irregular long crested waves with a 3D body is described. Incident waves are modeled using a recently developed pseudo-spectral method for fully-nonlinear free surface waves in water of finite depth. The wave generation process is based on submerged dipoles. The dipoles strengths and orientations are combined in such a way that waves are generated in a single direction. Furthermore, the wave generation transfer function is predetermined analytically, so that sea states of given energy spectrum are easily generated. The interaction of these waves with a 3D body is modeled using the 3D fully nonlinear BEM solver XWAVE, based on a formulation for the nonlinear diffracted flow. The effective coupling of both models is illustrated by simulating the diffraction of 2D wave packets as well as different realizations of ITTC wave spectra, by a vertical bottom-mounted cylinder.
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Campa, Giovanni, and Roberto Cademartori. "Influence of Nonlinear Flame Models on Thermoacoustic Instabilities in Combustion Chambers." In ASME Turbo Expo 2016: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/gt2016-57129.
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Thermoacoustic phenomena observed in gas turbine combustion chambers are usually related to a dependence of the heat release fluctuations to the velocity fluctuations at the injection point. Linear models for this dependence give information about stability, while nonlinear models can predict also limit cycles amplitude and frequency. This nonlinear dependence can be obtained by means of experiments or numerical tools by measuring the flame describing function (FDF). Analytical expressions have been proposed in the years to obtain nonlinear flame models to be introduced into simplified tools. Through these nonlinearities, information about limit cycle amplitudes, bifurcation diagrams and hysteresis can be achieved. The importance of this information is related to the possibility of managing the variation of certain operating parameters to keep the combustor in a safe operating zone. Additionally, from the bistable zone information about the operational margin can be obtained in order to stay far from the unstable condition. The aim of this work is to describe a simplified procedure to track combustors bifurcation diagrams using nonlinear flame models implemented in a 3D thermoacoustic tool based on the finite element methods (FEM) in the frequency domain. First flame describing functions (FDF) for not swirled and swirled burners from the literature are considered and applied to simplified configurations. Then, FDFs are introduced into an industrial configuration and the bifurcation diagrams are tracked. For both cases, the paper describes the influence of various FDFs parameters and shapes on the predictions of combustors stability boundaries.
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Caddemi, Salvatore, Ivo Caliò, Francesco Cannizzaro, Domenico D'Urso, Bartolomeo Pantò, Davide Rapicavoli, and Giuseppe Occhipinti. "3D Discrete Macro-Modelling Approach for Masonry Arch Bridges." In IABSE Symposium, Guimarães 2019: Towards a Resilient Built Environment Risk and Asset Management. Zurich, Switzerland: International Association for Bridge and Structural Engineering (IABSE), 2019. http://dx.doi.org/10.2749/guimaraes.2019.1825.
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<p>Masonry multi-span arch bridges are historical structures still playing a key role in many transportation networks of numerous countries. Most of these bridges are several decades old and have been subjected to continuous dynamic loadings, due to the vehicular traffic, and in many cases their maintenance required structural modifications. The currently adopted health monitoring strategies are based on in situ inspections as well as structural assessments based on numerical models characterised by different levels of reliability according to the required purpose. Simplified approaches are generally adopted for fast structural evaluation, on the other hand more rigorous approaches are fundamental for a reliable structural assessment of these particular structures, often characterized by very complex geometrical layouts and structural alterations not always sufficiently documented. This paper presents an original Discrete Macro-Element Method (DMEM) that allows a reliable simulation of the linear and nonlinear response of masonry structures and masonry bridges characterised by a lower computational burden, compared to classical nonlinear FEM analyses, although maintaining a good accuracy. The method is applied to a real masonry bridges and the results are compared with those obtained from a more sophisticated three- dimensional nonlinear FEM model both in linear and nonlinear context.</p>
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BUENROSTRO, JAVIER, HYONNY KIM, ROBERT K. GOLDBERG, and TRENTON M. RICKS. "HYBRID EXPERIMENTAL AND NUMERICAL CHARACTERIZATION OF THE 3D RESPONSE OF WOVEN POLYMER MATRIX COMPOSITES." In Thirty-sixth Technical Conference. Destech Publications, Inc., 2021. http://dx.doi.org/10.12783/asc36/35940.
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The need for advanced material models to simulate the deformation, damage, and failure of polymer matrix composites under impact conditions is becoming critical as these materials are gaining increased usage in the aerospace and automotive industries. The purpose of this work is to characterize carbon epoxy fabrics for composite material models that rely on a large number of input parameters to define their nonlinear and 3D response; e.g. elastic continuum damage mechanics models or plasticity damage models [1, 2]. It is challenging to obtain large sets of experimental stress-strain curves, therefore, careful selection of physical experiments that exhibit nonlinear behavior is done to significantly reduce the cost of generating threedimensional material databases. For this work, plain weave carbon fabrics with 3k and 12k tows are manufactured by VARTM. Testing is done using MTS hydraulic test frames and 2D digital image correlation (DIC) to obtain experimental stress-strain curves for in-plane tension and shear as well as transverse shear. For cases where actual experimental data is either not available or difficult to obtain, the required model input is virtually generated using the NASA Glenn developed Micromechanics Analysis Method/Generalized Method of Cells (MAC/GMC) code. A viscoplastic polymer model is calibrated and utilized to model the matrix constituent within a repeating unit cell (RUC) of a plain weave carbon fiber fabric. Verification and validation of this approach is done using MAT213, a tabulated orthotropic material model in the finite element code LS-DYNA, which relies on 12 input stress-strain curves in various coordinate directions [2]. Based on the model input generated by the micromechanics analyses in combination with available experimental data, a series of coupon level verification and validation analyses are carried out using the MAT 213 composite model.
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Ammar, Hussein H., Victor H. Mucino, Peter Ngan, Richard J. Crout, and Osama M. Mukdadi. "Patient-Specific 3D Finite-Element Analysis of Miniscrew Implants During Orthodontic Treatment." In ASME 2009 International Mechanical Engineering Congress and Exposition. ASMEDC, 2009. http://dx.doi.org/10.1115/imece2009-13068.
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Miniscrew implants have seen increasing clinical use as orthodontic anchorage devices with demonstrated stability. The focus of this study is to develop and simulate operative factors, such as load magnitudes and anchor locations to achieve desired motions in a patient-specific 3D model undergoing orthodontic treatment with miniscrew implant anchorage. A CT scan of a patient skull was imported into Mimics software (Materialise, 12.1). Segmentation operations were performed on the images to isolate the mandible, filter out noise, then reconstruct a smooth 3D model. A model of the left canine was reconstructed with the PDL modeled as a thin solid layer. A miniscrew was modeled with dimensions based on a clinical implant (BMK OAS-T1207) then inserted into the posterior mandible. All components were volumetrically meshed and optimized in Mimics software. Elements comprising the mandible bone and teeth were assigned a material based on their gray value ranges in HU from the original scan, and meshes were exported into ANSYS software. All materials were defined as linear and isotropic. A nonlinear PDL was also defined for comparison. For transverse forces applied on the miniscrew, maximum stresses increased linearly with loading and appeared at the neck or first thread and in the cortical bone. A distal tipping force was applied on the canine, and maximum stresses appeared in the tooth at the crown and apex and in the bone at the compression surface. Under maximum loading, stresses in bone were sufficient for resorption. The nonlinear PDL exhibited lower stresses and deflections than the linear model due to increasing stiffness. Numerous stress concentrations were seen in all models. Results of this study demonstrate the potential of patient-specific 3D reconstruction from CT scans and finite-element simulation as a versatile and effective pre-operative planning tool for orthodontists.
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Chatzisavvas, Ioannis, Aydin Boyaci, Andreas Lehn, Marcel Mahner, Bernhard Schweizer, and Panagiotis Koutsovasilis. "On the Influence of Thrust Bearings on the Nonlinear Rotor Vibrations of Turbochargers." In ASME Turbo Expo 2016: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/gt2016-58168.
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This work investigates the influence of hydrodynamic thrust bearings on the lateral rotor oscillations. Four thrust bearing models are compared in terms of their predictions of the oil-film pressure (Reynolds equation), the oil-film temperature (energy equation) and the load capacity. A detailed thrust bearing model using the generalized Reynolds equation and the 3D energy equation, a model using the standard Reynolds equation with a 2D energy equation, a model where the standard Reynolds equation and the 2D energy equation are decoupled and finally an isothermal thrust bearing model are presented. It is shown that in lower rotational speeds, the four models produce almost the same results. However, as the rotational speed is increased, the necessity for a thermo-hydrodynamic model is demonstrated. Run-up simulations of a turbocharger rotor/bearing system are performed, using an isothermal thrust bearing model with different inlet oil-temperatures. The influence of the oil-temperature of the thrust bearing on the subsynchronous rotor oscillations is investigated. Finally, a thermo-hydrodynamic model is compared with an isothermal in run-up simulations, where the influence of the variable oil-viscosity is discussed.
Reports on the topic "3d nonlinear models"
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Preston, Leiph, and Mehdi Eliassi. Linear Seismic Source Equivalents in 3D Nonlinear Models: Effects of Embedded Small-Scale, Near-Source Structures. Office of Scientific and Technical Information (OSTI), September 2022. http://dx.doi.org/10.2172/1885641.
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Badia, S., A. Martín, J. Principe, C. Soriano, and R. Rossi. D3.1 Report on nonlinear domain decomposition preconditioners and release of the solvers. Scipedia, 2021. http://dx.doi.org/10.23967/exaqute.2021.2.021.
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This document describes the industrial application, on which the developments of the project are implemented, and the CFD set-up. The developments are implemented over six analysis cases with increasing complexity starting from a 2D geometry with mean wind inflow to a 3D geometry with turbulent inflow and real-time shape optimization. The application represents the CAARC tall building model, which has served as a benchmark model for many studies since the 1970’s when it was first developed. Base moments (bending and torsional moments) of the building are extracted for validation by comparison of the results with the benchmark study. Page 3 of 19 Deliverable 7.1
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LOCAL BUCKLING (WRINKLING) OF PROFILED METAL-FACED INSULATING SANDWICH PANELS – A PARAMETRIC STUDY. The Hong Kong Institute of Steel Construction, August 2022. http://dx.doi.org/10.18057/icass2020.p.248.
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This study aims to investigate the effects of various parameters including the height of the profiling region, spacing of profiling ribs, length of the panel, thickness and modulus of the foam core, and thickness of the profiled face sheet, on the local buckling capacity of profiled metal faced insulating sandwich panels. A simplified finite element (FE) modeling approach that models the profiled face sheet as a folded plate structure resting on elastic foundation is adopted. This modeling approach was validated through comparison with tests results and 3D FE modeling of the entire sandwich structure in a previous study conducted by the authors. The two-parameter elastic foundation properties are determined using a modified nonlinear Vlasov foundation model. The results show that all the above-mentioned parameters play important roles in controlling the buckling capacity of the panel. However, the slenderness ratio of the panel is the most dominant parameter among all. Understanding the influence of each of the aforementioned parameters aids in the design process of such panels and provides insight into their local buckling response.
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SEISMIC PERFORMANCE OF SPATIAL STEEL BEAM-COLUMN CONNECTIONS. The Hong Kong Institute of Steel Construction, August 2022. http://dx.doi.org/10.18057/icass2020.p.125.
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This paper presents a finite element analysis for spatial beam-column connections in steel frame to better understand the structural behavior of spatial connections. After the simulation and validation of experimental results, a total of 7 refined 3D models, including beam-to-column connections at different positions in the steel frame, were created and analyzed cyclically through the nonlinear finite element program ABAQUS to investigate the spatial coupling effect. The momentrotation relationships and TI index distribution across the width of beam flanges, were discussed in detail to elucidate the mechanical performance interaction between strong-axis and weak-axis connections. Results showed that there is obvious interaction between two beams in strong-axis or weak-axis connections, and the plane exterior connections has better hysteresis performance. While the interaction of strong-axis connection and weak-axis connection slightly affected each other’s hysteresis performance, and thus the coupling effect of spatial connections is not evident.
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SIMPLIFIED MODELLING OF NOVEL NON-WELDED JOINTS FOR MODULAR STEEL BUILDINGS. The Hong Kong Institute of Steel Construction, December 2021. http://dx.doi.org/10.18057/ijasc.2021.17.4.10.
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Prefabricated modular steel (PFMS) construction is a more efficient and safe method of constructing a high-quality building with less waste material and labour dependency than traditional steel construction. It is indeed critical to have a precise and valuable intermodular joining system that allows for efficient load transfer, safe handling, and optimal use of modular units' strength. Thus, the purpose of this study was to develop joints using tension bolts and solid tenons welded into the gusset plate (GP). These joints ensured rigid and secure connectivity in both horizontal and vertical directions for the modular units. Using the three-dimensional (3D) finite element (FE) analysis software ABAQUS, the study investigated the nonlinear lateral structural performance of the joint and two-storey modular steel building (MSB). The solid element FE models of joints were then simplified by introducing connectors and beam elements to enhance computational efficiency. Numerous parameters indicated that column tenons were important in determining the joint's structural performance. Moreover, with a standard deviation (SD) of 0.025, the developed connectors and beam element models accurately predicted the structural behaviour of the joints. As a result of their simplification, these joints demonstrated effective load distribution, seismic performance, and ductility while reducing computational time, effort, and complexity. The validity of the FE analysis was then determined by comparing the results to the thirteen joint bending tests performed in the reference.
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A SIMPLE METHOD FOR A RELIABLE MODELLING OF THE NONLINEAR BEHAVIOUR OF BOLTED CONNECTIONS IN STEEL LATTICE TOWERS. The Hong Kong Institute of Steel Construction, March 2022. http://dx.doi.org/10.18057/ijasc.2022.18.1.6.
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The behaviour of bolted connections in steel lattice transmission line towers affects their load-bearing capacity and failure mode. Bolted connections are commonly modelled as pinned or fixed joints, but their behaviour lies between these two extremes and evolves in a nonlinear manner. Accordingly, an accurate finite element modelling of the structural response of complete steel lattice towers requires the consideration of various nonlinear phenomena involved in bolted connexions, such as bolt slippage. In this study, a practical method is proposed for the modelling of the nonlinear response of steel lattice tower connections involving one or multiple bolts. First, the local load-deformation behaviour of single-bolt lap connections is evaluated analytically depending on various geometric and material parameters and construction details. Then, the predicted nonlinear behaviour for a given configuration serves as an input to a 2D/3D numerical model of the entire assembly of plates in which the bolted joints are represented as discrete elements. For comparison purposes, an extensive experimental study comprising forty-four tests were conducted on steel plates assembled with one or two bolts. This approach is also extended to simulate the behaviour of assemblies including four bolts and the obtained results are checked against experimental datasets from the literature. The obtained results show that the proposed method can predict accurately the response of a variety of multi-bolt connections. A potential application of the strategy developed in this paper could be in the numerical modelling of full-scale steel lattice towers, particularly for a reliable estimation of the displacements.