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Littérature scientifique sur le sujet « Deformations of D-Structures »

Auteur : Grafiati

Publié le 9 mars 2023

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Articles de revues sur le sujet "Deformations of D-Structures"

Hassan, S. F. « O(d,d;R) deformations of complex structures and extended worldsheet supersymmetry ». Nuclear Physics B 454, n^o 1-2 (novembre 1995) : 86–102. http://dx.doi.org/10.1016/0550-3213(95)00384-5.

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BYTSENKO, A. A. « BRST-INVARIANT DEFORMATIONS OF GEOMETRIC STRUCTURES IN SIGMA MODELS ». International Journal of Modern Physics A 26, n^o 22 (10 septembre 2011) : 3769–80. http://dx.doi.org/10.1142/s0217751x11054231.

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The closed string correlators can be constructed from the open ones using topological string theories as a model. The space of physical closed string states is isomorphic to the Hochschild cohomology of (A,Q) (operator Q of ghost number one), - this statement has been verified by means of computation of the Hochschild cohomology of the category of D -branes. We study a Lie algebra of formal vector fields Wn with its application to the perturbative deformed holomorphic symplectic structure in the A -model, and a Calabi-Yau manifold with boundaries in the B -model. We show that equivalent classes of deformations are describing by a Hochschild cohomology theory of the DG-algebra, [Formula: see text], [Formula: see text], which is defined to be the cohomology of (-1)nQ+d Hoch . Here [Formula: see text] is the initial non-deformed BRST operator while ∂ deform is the deformed part whose algebra is a Lie algebra of linear vector fields gl n. We assume that if in the theory exists a single D -brane then all the information associated with deformations is encoded in an associative algebra A equipped with a differential [Formula: see text]. In addition equivalence classes of deformations of these data are described by a Hochschild cohomology of (A,Q), an important geometric invariant of the (anti)holomorphic structure on X. We also discuss the identification of the harmonic structure (HT•(X); HΩ•(X)) of affine space X and the group [Formula: see text] (the HKR isomorphism), and bulk-boundary deformation pairing.

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BYTSENKO, A. A. « BRST-INVARIANT DEFORMATIONS OF GEOMETRIC STRUCTURES IN SIGMA MODELS ». International Journal of Modern Physics : Conference Series 03 (janvier 2011) : 75–86. http://dx.doi.org/10.1142/s2010194511001164.

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The closed string correlators can be constructed from the open ones using topological string theories as a model. The space of physical closed string states is isomorphic to the Hochschild cohomology of (A, Q) (operator Q of ghost number one), - this statement has been verified by means of computation of the Hochschild cohomology of the category of D-branes. We study a Lie algebra of formal vector fields Wn with its application to the perturbative deformed holomorphic symplectic structure in the A-model, and a Calabi-Yau manifold with boundaries in the B-model. We show that equivalent classes of deformations are describing by a Hochschild cohomology theory of the DG-algebra [Formula: see text], [Formula: see text], which is defined to be the cohomology of (-1)n Q + d Hoch . Here [Formula: see text] is the initial non-deformed BRST operator while ∂deform is the deformed part whose algebra is a Lie algebra of linear vector fields gl n. We assume that if in the theory exists a single D-brane then all the information associated with deformations is encoded in an associative algebra A equipped with a differential [Formula: see text]. In addition equivalence classes of deformations of these data are described by a Hochschild cohomology of (A, Q), an important geometric invariant of the (anti)holomorphic structure on X. We also discuss the identification of the harmonic structure (HT•(X); HΩ•(X)) of affine space X and the group [Formula: see text] (the HKR isomorphism), and bulk-boundary deformation pairing.

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Cingolani, Matteo, Gioia Fusaro, Giulia Fratoni et Massimo Garai. « Influence of thermal deformations on sound absorption of three-dimensional printed metamaterials ». Journal of the Acoustical Society of America 151, n^o 6 (juin 2022) : 3770–79. http://dx.doi.org/10.1121/10.0011552.

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Acoustic metamaterials (AMMs) are designed with complex geometrical shapes to obtain unconventional sound-absorbing performances. As additive manufacturing is particularly suited to print complex structures in a more straightforward and controllable way, AMMs often exploit three-dimensional (3-D) printing techniques. However, when exposed to different temperature conditions, such structures can be affected by geometrical deformations, especially when they are polymer-based. This can cause a mismatch between the experimental data and the expected theoretical performance; therefore, it is important to take thermal effects into account. The present paper investigates the influence of thermal deformations on the sound absorption of three geometries: a coplanar spiral tube, a system with double coiled resonators, and a neck-embedded resonator. Measurements were performed on each 3-D printed specimen in the impedance tube after the samples had been placed in a climate chamber to modify the temperature settings (T = 10–50 °C). Numerical models, validated on the measurements, were employed to quantify the geometrical deformation of AMM structures through a multiphysics approach, highlighting the effects of thermal stress on the acoustic behavior. The main outcomes prove that the frequency shifts of sound absorption peaks depend on temperature configurations and follow exponential regressions, in accordance with previous literature on polymeric materials.

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Eriksen, Eivind. « Computing Noncommutative Deformations of Presheaves and Sheaves of Modules ». Canadian Journal of Mathematics 62, n^o 3 (1 juin 2010) : 520–42. http://dx.doi.org/10.4153/cjm-2010-015-6.

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AbstractWe describe a noncommutative deformation theory for presheaves and sheaves of modules that generalizes the commutative deformation theory of these global algebraic structures and the noncommutative deformation theory of modules over algebras due to Laudal.In the first part of the paper, we describe a noncommutative deformation functor for presheaves of modules on a small category and an obstruction theory for this functor in terms of global Hochschild cohomology. An important feature of this obstruction theory is that it can be computed in concrete terms in many interesting cases.In the last part of the paper, we describe a noncommutative deformation functor for quasi-coherent sheaves of modules on a ringed space (X,𝒜). We show that for any good A-affine open cover U of X, the forgetful functor QCoh𝒜 → PreSh(U,𝒜) induces an isomorphism of noncommutative deformation functors.Applications. We consider noncommutative deformations of quasi-coherent 𝒜-modules on X when (X,𝒜) = (X,𝒪X) is a scheme or (X,𝒜) = (X,𝒟) is a D-scheme in the sense of Beilinson and Bernstein. In these cases, we may use any open affine cover of X closed under finite intersections to compute noncommutative deformations in concrete terms using presheaf methods. We compute the noncommutative deformations of the left 𝒟X-module 𝒟X when X is an elliptic curve as an example.

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KAPUSTIN, ANTON. « TOPOLOGICAL STRINGS ON NONCOMMUTATIVE MANIFOLDS ». International Journal of Geometric Methods in Modern Physics 01, n^o 01n02 (avril 2004) : 49–81. http://dx.doi.org/10.1142/s0219887804000034.

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We identify a deformation of the N=2 supersymmetric sigma model on a Calabi–Yau manifold X which has the same effect on B-branes as a noncommutative deformation of X. We show that for hyperkähler X such deformations allow one to interpolate continuously between the A-model and the B-model. For generic values of the noncommutativity and the B-field, properties of the topologically twisted sigma-models can be described in terms of generalized complex structures introduced by N. Hitchin. For example, we show that the path integral for the deformed sigma-model is localized on generalized holomorphic maps, whereas for the A-model and the B-model it is localized on holomorphic and constant maps, respectively. The geometry of topological D-branes is also best described using generalized complex structures. We also derive a constraint on the Chern character of topological D-branes, which includes A-branes and B-branes as special cases.

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BYTSENKO, A. A., M. CHAICHIAN, A. TUREANU et F. L. WILLIAMS. « BRST-INVARIANT DEFORMATIONS OF GEOMETRIC STRUCTURES IN TOPOLOGICAL FIELD THEORIES ». International Journal of Modern Physics A 28, n^o 16 (28 juin 2013) : 1350069. http://dx.doi.org/10.1142/s0217751x13500693.

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We study a Lie algebra of formal vector fields Wn with its application to the perturbative deformed holomorphic symplectic structure in the A-model, and a Calabi–Yau manifold with boundaries in the B-model. A relevant concept in the vertex operator algebra and the BRST cohomology is that of the elliptic genera (the one-loop string partition function). We show that the elliptic genera can be written in terms of spectral functions of the hyperbolic three-geometry (which inherits the cohomology structure of BRST-like operator). We show that equivalence classes of deformations are described by a Hochschild cohomology theory of the DG-algebra [Formula: see text], which is defined to be the cohomology of (-1)n Q + d Hoch . Here, [Formula: see text] is the initial nondeformed BRST operator while ∂ deform is the deformed part whose algebra is a Lie algebra of linear vector fields gl n. We discuss the identification of the harmonic structure (HT•(X);HΩ•(X)) of affine space X and the group [Formula: see text] (the HKR isomorphism), and bulk-boundary deformation pairing.

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Yuge, K., N. Iwai et N. Kikuchi. « Optimization of 2-D structures subjected to nonlinear deformations using the homogenization method ». Structural Optimization 17, n^o 4 (décembre 1999) : 286–99. http://dx.doi.org/10.1007/bf01207005.

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Correa, Francisco, et Olaf Lechtenfeld. « Algebraic integrability of PT -deformed Calogero models ». Journal of Physics : Conference Series 2038, n^o 1 (1 octobre 2021) : 012007. http://dx.doi.org/10.1088/1742-6596/2038/1/012007.

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Abstract We review some recents developments of the algebraic structures and spectral properties of non-Hermitian deformations of Calogero models. The behavior of such extensions is illustrated by the A 2 trigonometric and the D 3 angular Calogero models. Features like intertwining operators and conserved charges are discussed in terms of Dunkl operators. Hidden symmetries coming from the so-called algebraic integrability for integral values of the coupling are addressed together with a physical regularization of their action on the states by virtue of a PT -symmetry deformation.

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Vilfayeau, Jerome, David Crépin, François Boussu, Damien Soulat et Philippe Boisse. « Numerical Modelling of the Weaving Process for Textile Composite ». Key Engineering Materials 554-557 (juin 2013) : 472–77. http://dx.doi.org/10.4028/www.scientific.net/kem.554-557.472.

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Due to advancements made in 3D weaving process [1] and, in order to develop 3D textile structure as reinforcement of composite material for aeronautic application, a good prediction of the geometry and the mechanical properties of the 3D woven unit cell is required. Due to the complexity of these textile architectures, realistic geometric representations [2] of fabrics are often difficult to obtain especially for 3D woven fabrics, but these descriptions are necessary to define meshes for finite element computation [3]. At present, existing tools which model and define, early at a mesoscopic scale [4], the architecture of 3D fabrics don’t take into account the influence of the manufacturing process on the shape modification of the textile structure. Some numerical model exists for the braiding process [5] and the knitting process [6], but not yet for the weaving process. During the manufacturing process, fibres are subjected to significant deformations due to loads from the component of the loom or from the friction with the others fibres. These significant deformations lead to mechanical strength losses of the fabric. A numerical model of the different steps of the weaving process could predict these significant deformations and their influence on the geometry of the textile architecture. Thus, the objective of the NUMTISS project is to develop a numerical model of the deformation of the yarn during the weaving process. For the numerical modelling of the weaving process developed in finite element method, we considered all loom elements like rigid solid, and we will make the assumption that yarns are transverse isotropic elastic materials. Simulations of the process for a plain weave, a twill 2-2 and a satin 8 fabric have already been performed, as well as the simulation of orthogonal warp interlock structures. Then, to understand the kinematic motions of weaving process, the tracking of some strategic elements on the industrial weaving loom (reed, heddles, rapier,..) have been carried out. The tracking obtained from the video of the high speed camera will help us to define the numerical model of the weaving kinematic closer to reality. Correlations between numerical results and specific structures in glass fibres produced on the loom will be presented. The influence of each step of the manufacturing process on the characteristics of the textile structure could be analyzed [1]X. Chen, L. W. Taylor, L. J.Tsai. ”An overview on fabrication of three-dimensional woven textile preforms for composites”. Textile Research Journal, 2011, 81(9) 932–944 [2] SV Lomov, G Perie, DS Ivanov, I Verpoest and D Marsal. “Modeling three-dimensional fabrics and three-dimensional reinforced composites: challenges and solutions”. Textile Research Journal, 2011, 81(1) 28–41 [3] E. De Luycker, F. Morestin, P. Boisse, D. Marsal. « Simulation of 3D interlock composite performing”. Composite Structures, Volume 88, Issue 4, May 2009, Pages 615-623. [4] M. Ansar, W. Xinwei, Z. Chouwei. “Modeling strategies of 3D woven composites: A review”. Composite Structures 93 (2011) 1947–1963. [5] A. K. Pickett, J. Sirtautas, et A. Erber. « Braiding simulation and prediction of mechanical properties”. Applied Composite Materials, 2009. [6] M. Duhovic, D. Bhattacharyya. “Simulating the deformation mechanisms of knitted fabric composites”. Composites Part A : Applied Science and Manufacturing, 2006.

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Thèses sur le sujet "Deformations of D-Structures"

ROSSI, FEDERICO ALBERTO. « D-Complex Structures on Manifolds : Cohomological properties and deformations ». Doctoral thesis, Università degli Studi di Milano-Bicocca, 2013. http://hdl.handle.net/10281/41976.

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In questa tesi studiamo alcune proprietà delle "Varietà Doppie" o D-Varietà. In particolare studiamo la teoria delle deformazioni di D-Strutture e di D-Strutture CR, e troviamo una condizione che è equivalente alla classica condizione di Maurer-Cartan che descrive l'integrabilità di deformazioni di D-Strutture. Successivamente prestiamo attenzione alla coomologia delle D-Varietà, provando che una versione D-complessa del del-delbar-Lemma non può essere vera per D-varietà compatte. Inoltre sono stabilite alcune proprietà di sottogruppi speciali della coomologia di de-Rham, ottenute studiando il loro comportamento sotto l'azione di deformazioni. Infine, un risultato riguardante le sottovarietà Lagrangiane minimali dovuto ad Harvey e Lawson riguardante le varietà D-Kahler Ricci-Piatte è generalizzato a una classe di varietà simplettiche quasi D-complesse.
We study some properties of Double Manifold, or D-Manifolds. In particular, we study of deformations of D-structures and of CR D-structures, and we found a condition which is equivalent to the classical Maurer-Cartan equation describing the integrability of the deformations. We also focus on the cohomological properties of D-Manifold, showing that a del-delbar-Lemma can not hold for any compact D-Manifold. We also state some properties of special subgroups of de-Rham cohomology, studing also their behaviour under small deformations. Finally, a result by Harvey and Lawson about the minimal Lagrangian Submanifold of a D-Kahler Ricci-flat manifold is generalized to the case of a special almost D-complex symplectic manifold.

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Recio, Molina Juan Antonio. « Hydraulic stability of geotextile sand containers for coastal structures effect of deformations and stability formulae ». Clausthal-Zellerfeld Papierflieger, 2007. http://d-nb.info/987276026/04.

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Bassa, Bruno. « Contribution à l’étude d’éléments finis de type coque sans degrés de liberté en rotation ou à formulation solide pour des simulations numériques de l’emboutissage et du retour élastique ». Thesis, Lyon, INSA, 2011. http://www.theses.fr/2011ISAL0113/document.

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La thèse présente une méthodologie pour construire des éléments finis de type « solide-coque » avec intégration réduite en vue des applications à la simulation de la mise en forme tel que l’emboutissage des tôles où ces éléments finis doivent présenter de bonnes aptitudes à modéliser la flexion mais également les situations de laminage de la tôle. A partir des éléments volumiques à 8 nœuds et 3 degrés de liberté par nœud (les 3 composantes du déplacement), un neuvième nœud est rajouté au centre de l’élément. Ce neuvième nœud n’est pourvu que d’un seul degré de liberté, le déplacement le long de la direction de l’épaisseur. Cette direction privilégiée a un nombre de points d’intégration supérieur ou égal à 3 mais l’intégration est réduite au centre de l’élément diminuant très sensiblement les temps CPU par rapport à une intégration complète. Un soin particulier a été pris pour contrôler tous les modes à énergie nulle dus à l’intégration réduite. Ce nœud supplémentaire permet une distribution linéaire de la déformation normale. Avec les lois de comportement complètement 3D ces nouveaux éléments solide-coque donnent des résultats similaires en flexion à ceux obtenus avec des éléments coques et état plan de contrainte. Le neuvième nœud joue le rôle d’un paramètre supplémentaire pour l’interpolation quadratique du déplacement dans la direction de l’épaisseur. Ce degré de liberté a une signification physique et un effort équivalent à une pression normale peut être prescrit. Dans les situations de pression normale et dans le cas du contact, la contrainte normale obtenue est physique ce qui n’est pas le cas de nombreux éléments solide-coque de la littérature. Le pincement ou le laminage des tôles est correctement modélisé. Pour valider ces éléments, un module d’emboutissage en U avec passage et laminage de la bande de tôle sur des rouleaux a été construit au laboratoire. La comparaison entre les efforts d’emboutissage calculés et mesurés est très bonne ainsi que la géométrie des bandes de tôle obtenue après retour élastique
This thesis presents a methodology for developing under-integrated “solid-shell” finite elements for sheet forming simulations like deep drawing where these elements must offer a bending capability and sheet thinning conditions as well. Starting from 8-node elements endowing three degrees of freedom per node (three displacement components), a ninth node is added at the centre of the element. This extra node has just one degree of freedom: a displacement along the ‘thickness’ direction. Several integration points are distributed along this privileged direction (5 points, generally) but the in-plane reduced integration at the centre of the element decreases CPU costs compared to a full integration. A special care has been taken to control all zero-energy modes due to the reduced integration. This additional node allows a linear distribution of the normal strain. With fully-3D constitutive laws, these new solid-shell elements give similar bending results as those obtained with shell elements and a plane stress state hypothesis. This ninth node acts as an additional parameter for the quadratic interpolation of the displacement in the ‘thickness’ direction. The corresponding degree of freedom has a physical meaning and a force, equivalent to a normal pressure for instance, may be prescribed. In situations of a normal pressure and in the case of contact, the obtained normal stress is physically defined, which is not the case for many solid-shell elements found in the literature. The pinching (or the thinning) of sheets is properly modelled. To validate these elements, an apparatus for U-drawing tests with ironing or thinning on strip sheets has been built in the laboratory. The comparison between numerical and experimental punch force during sheet forming is pretty good as well as the geometry of blank after springback

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Rollenske, Sönke [Verfasser]. « Nilmanifolds : complex structures, geometry and deformations / Sönke Rollenske ». 2007. http://d-nb.info/985385464/34.

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Stelzig, Philipp Emanuel [Verfasser]. « Homogenization of many-body structures subject to large deformations and noninterpenetration / Philipp Emanuel Stelzig ». 2009. http://d-nb.info/1000121763/34.

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Recio, Molina Juan Antonio [Verfasser]. « Hydraulic stability of geotextile sand containers for coastal structures : effect of deformations and stability formulae / von Juan Antonio Recio Molina ». 2008. http://d-nb.info/987929720/34.

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Yi-HsuanLi et 李怡萱. « R ＆ D of Gradient Structure Design Effects on Plastic Deformation of Ti-6Al-4V Porous Materials ». Thesis, 2019. http://ndltd.ncl.edu.tw/handle/xen4cc.

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Livres sur le sujet "Deformations of D-Structures"

Rozenblyum, Nick, et Dennis Gaitsgory. Study in Derived Algebraic Geometry : Volume II : Deformations, Lie Theory and Formal Geometry. American Mathematical Society, 2020.

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Chapitres de livres sur le sujet "Deformations of D-Structures"

Mannacio, Francesco, Fabrizio Di Marzo, Marco Gaiotti, Massimo Guzzo, Cesare Mario Rizzo et Marco Venturini. « Shock Characterization of Fiberglass Composite Laminates : Numerical and Experimental Comparison ». Dans Progress in Marine Science and Technology. IOS Press, 2022. http://dx.doi.org/10.3233/pmst220048.

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When subjected to a no contact underwater explosions (UNDEX), naval composite structures show highly nonlinear deformations. In this paper, fiberglass composite laminates are characterized dynamically. Experimentally, modal analyses are carried out to determine the modal parameters of the specimens, while dedicated shock tests are performed using the MIL S 901 D Medium Weight Shock Machine to measure their shock deformations. Numerically, finite element model is built up, running both modal and implicit dynamic analyses to predict the structural response of different E-Glass laminates. In the end, results obtained by calculations are compared with experimental data, validating the model.

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Klokočník, Jaroslav, Aleš Bezděk et Jan Kostelecký. « Gravity field aspects for identification of cosmic impact structures on Earth ». Dans In the Footsteps of Warren B. Hamilton : New Ideas in Earth Science. Geological Society of America, 2022. http://dx.doi.org/10.1130/2021.2553(21).

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ABSTRACT We studied the following proven as well as hypothetical impact craters (among others), and some of the relevant results are reviewed in this chapter: (1) a hypothetical impact structure in Saginaw Bay, Great Lakes, Michigan; (2) a putative impact crater basin under the ice of Antarctica in Wilkes Land; (3) two recently discovered subglacial impact craters in Greenland; (4) a possible huge impact crater in Kotuykanskaya in a remote area of Siberia near the proven impact crater Popigai; and (5) a hypothetical impact object Burckle on the bottom of the Indian Ocean. They were tested using the gravity data derived from the recent gravity field model EIGEN 6C4 (with ground resolution of ~9 km). Our method is novel; we introduce gravity aspects (descriptors) to augment traditional gravity anomalies. The following gravity aspects were used: (a) gravity disturbances/anomalies, (b) second derivatives of the disturbing potential (the Marussi tensor), (c) two of three gravity invariants, (d) their specific ratio (known as 2D factor), (e) strike angles, and (f) virtual deformations. These gravity aspects are sensitive in various ways to the underground density contrasts. They describe the underground structures (not only the craters) more carefully and in more detail than the traditional gravity anomalies could do alone. Our results support geological evidence of the impact craters found by others in many cases or suggest new impact places for further study.

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Ogawa, Yujiro, et Shin’ichi Mori. « Gravitational sliding or tectonic thrusting ? : Examples and field recognition in the Miura-Boso subduction zone prism ». Dans Plate Tectonics, Ophiolites, and Societal Significance of Geology : A Celebration of the Career of Eldridge Moores. Geological Society of America, 2021. http://dx.doi.org/10.1130/2021.2552(10).

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ABSTRACT Discrimination between gravity slides and tectonic fold-and-thrust belts in the geologic record has long been a challenge, as both have similar layer shortening structures resulting from single bed duplication by thrust faults of outcrop to map scales. Outcrops on uplifted benches within the Miocene to Pliocene Misaki accretionary unit of Miura-Boso accretionary prism, Miura Peninsula, central Japan, preserve good examples of various types of bedding duplication and duplex structures with multiple styles of folds. These provide a foundation for discussion of the processes, mechanisms, and tectonic implications of structure formation in shallow parts of accretionary prisms. Careful observation of 2-D or 3-D and time dimensions of attitudes allows discrimination between formative processes. The structures of gravitational slide origin develop under semi-lithified conditions existing before the sediments are incorporated into the prism at the shallow surfaces of the outward, or on the inward slopes of the trench. They are constrained within the intraformational horizons above bedding-parallel detachment faults and are unconformably covered with the superjacent beds, or are intruded by diapiric, sedimentary sill or dike intrusions associated with liquefaction or fluidization under ductile conditions. The directions of vergence are variable. On the other hand, layer shortening structure formed by tectonic deformation within the accretionary prism are characterized by more constant styles and attitudes, and by strong shear features with cataclastic textures. In these structures, the fault surfaces are oblique to the bedding, and the beds are systematically duplicated (i.e., lacking random styles of slump folds), and they are commonly associated with fault-propagation folds. Gravitational slide bodies may be further deformed at deeper levels in the prism by tectonism. Such deformed rocks with both processes constitute the whole accretionary prism at depth, and later may be deformed, exhumed to shallow levels, and exposed at the surface of the trench slope, where they may experience further deformation. These observations are not only applicable in time and space to large-scale thrust-and-fold belts of accretionary prism orogens, but to small-scale examples. If we know the total 3-D geometry of geologic bodies, including the time and scale of deformational stages, we can discriminate between gravitational slide and tectonic formation of each fold-and-thrust belt at the various scales of occurrence.

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Hosseinzadeh, Saeed, et Kristjan Tabri. « Numerical Investigation of Hydroelastic Response of a Three-Dimensional Deformable Hydrofoil ». Dans Progress in Marine Science and Technology. IOS Press, 2020. http://dx.doi.org/10.3233/pmst200029.

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The present study is concerned with the numerical simulation of Fluid-Structure Interaction (FSI) on a deformable three-dimensional hydrofoil in a turbulent flow. The aim of this work is to develop a strongly coupled two-way fluid-structure interaction methodology with a sufficiently high spatial accuracy to examine the effect of turbulent and cavitating flow on the hydroelastic response of a flexible hydrofoil. A 3-D cantilevered hydrofoil with two degrees-of-freedom is considered to simulate the plunging and pitching motion at the foil tip due to bending and twisting deformation. The defined problem is numerically investigated by coupled Finite Volume Method (FVM) and Finite Element Method (FEM) under a two-way coupling method. In order to find a better understanding of the dynamic FSI response and stability of flexible lifting bodies, the fluid flow is modeled in the different turbulence models and cavitation conditions. The flow-induced deformation and elastic response of both rigid and flexible hydrofoils at various angles of attack are studied. The effect of three-dimension body, pressure coefficient at different locations of the hydrofoil, leading-edge and trailing-edge deformation are presented and the results show that because of elastic deformation, the angle of attack increases and it lead to higher lift and drag coefficients. In addition, the deformations are generally limited by stall condition and because of unsteady vortex shedding, the post-stall condition should be considered in FSI simulation of deformable hydrofoil. To evaluate the accuracy of the numerical model, the present results are compared and validated against published experimental data and showed good agreement.

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Li, Shuaiheng, Chen Zhu, Zhousheng Huang et Haiyan Sun. « Experimental Study on Strength and Deformation Characteristics of Cement Soil Under Wet and Dry Cycle ». Dans Advances in Transdisciplinary Engineering. IOS Press, 2022. http://dx.doi.org/10.3233/atde220931.

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Jiangsu province, located in the middle and lower reaches of the Yangtze River, suffers from rainfall and temperature and humidity changes, which has a significant impact on the structure of road base and foundation soil in the cyclic wet and dry cycle process, impacting and endangering the strength and deformation characteristics of soil. This paper studies the road base filling in Shanghai-Shaanxi Expressway for strength characteristics and change rules of cement improved foundation soil under the wet and dry cycle, and discusses the influence of cement admixture, age and number of dry and wet cycles on the strength of cement improved road base soil. The results show that the higher the cement admixture and the longer the curing age, the higher the compressive strength of cured foundation soil; the cured foundation soil tends to slow down gradually in strength growth with the increase of age, and slows down obviously after 28 d; the wet and dry cycle process will have an irreversible impact on the structure of cured foundation soil, slowing down or even reversing the strength growth rate of cured foundation soil, which can be reduced by increasing cement admixture.

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« Figure 5 : Computer simulation of mode-II shear fracture in jointed pier-wall system. Experimental and numerical load-displacement curves for top left node. Incremental deformations at four stages (a) to (d) of the loading process. » Dans Fracture and Damage in Quasibrittle Structures, 237–46. CRC Press, 1994. http://dx.doi.org/10.1201/9781482271454-8.

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« slope supporting structure have shown significant sensor. The main structure of the strain sensor cracks and deformation, as shown in Figure 1. includes steel pipes for pasting the Bragg grating, a flange for fixing the sensor, self-locking nuts for fixing the armored cable, and so on. When the strain sensors are buried in the strain pile, the flange is firmly fixed in the mortar of the strain pile so that the flange can make the fiber Bragg grating strained in the axial direction. The center wavelength shift of the wf a se c ro B nr n ae g cg t ed to the main control room ; the server d afo c uw is t ion and analysis on the data sent by sensors. The server was able to be remotely accessed th rough the network for checking the stability of the s eΛ i s uh c monitoringof the structural stabilityof the mountain ». Dans Structural Health Monitoring and Integrity Management, 397–99. CRC Press, 2015. http://dx.doi.org/10.1201/b18510-127.

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Actes de conférences sur le sujet "Deformations of D-Structures"

Garg, Ajay. « 2-D Finite Element Analysis of Engineering Components ». Dans ASME 1995 15th International Computers in Engineering Conference and the ASME 1995 9th Annual Engineering Database Symposium collocated with the ASME 1995 Design Engineering Technical Conferences. American Society of Mechanical Engineers, 1995. http://dx.doi.org/10.1115/cie1995-0741.

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Abstract Design and analysis of engineering components can be categorized under the theory of continuum mechanics, plates/shells or beams. Closed form solutions for determining deformations and stresses are available for simple structures with simple boundary conditions. In the cases of complex structures, boundary conditions and loads, analytical solutions are not readily available. Finite element analysis (FEA) can be performed to resolve the simulation barrier of these analytically indeterminate structures. Similar to analytical approach, FEA can simulate the components through solid, plate/shell or beam elements. Finite element analysis through 3-D solid elements is costly and may require time in weeks, which may not be at the disposal of an analyst. Axi-symmetric components and components with an infinite radius of curvature (flat surfaces), but with complex cross sections can be modeled by 2-D axi-symmetric and plate elements, respectively. Two dimensional finite elements require less time and hardware support than three-dimensional elements. Two development cases of successful application of 2-D finite elements instead of 3-D finite elements are discussed. Experimental and analytical verification of FEA results, and guidelines for checking finite element mesh discretization error are presented.

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Kim, Jihyeon, et Narakorn Srinil. « 3-D Numerical Simulations of Subsea Jumper Transporting Intermittent Slug Flows ». Dans ASME 2018 37th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/omae2018-77299.

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Subsea jumper is the steel pipe structure to connect wellhead and subsea facilities such as manifolds or processing units in order to transport the produced multiphase flows. Generally, the jumper consists of a goalpost with two loop structures and a straight pipe between them, carrying the multiphase oil and gas from the producing well. Due to the jumper pipe characteristic geometry and multi-fluid properties, slug flows may take place, creating problematic fluctuating forces causing the jumper oscillations. Severe dynamic fluctuations cause the risk of pipe deformations and resonances resulting from the hydrodynamic momentum/pressure forces which can lead to unstable operating pressure and decreased production rate. Despite the necessity to design subsea jumper with precise prediction on the process condition and the awareness of slug flow risks, it is challenging to experimentally evaluate, identify and improve the modified design in terms of the facility scale, time and cost efficiency. With increasing high computational performance, numerical analysis provides an alternative approach to simulate multiphase flow-induced force effects on the jumper. The present paper discusses the modelling of 3-D flow simulations in a subsea jumper for understanding the development process of internal slug flows causing hydrodynamic forces acting on the pipe walls and bends. Based on the fluctuating pressure calculated by the fluid solver, dynamic responses of the jumper pipe are assessed by a one-way interaction approach to evaluate deformation and stress. A potential resonance is discussed with the jumper modal analysis. Results from the structural response analyses show dominant multi-modal frequencies due to intermittent slug flow frequencies. Numerical results and observed behaviors may be useful for a comparison with other simulation and experiment.

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Sofla, Aarash Y. N., Dana M. Elzey et Haydn N. G. Wadley. « An Antagonistic Flexural Unit Cell for Design of Shape Morphing Structures ». Dans ASME 2004 International Mechanical Engineering Congress and Exposition. ASMEDC, 2004. http://dx.doi.org/10.1115/imece2004-62149.

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An antagonistic flexural unit cell (AFC) concept for the design and fabrication of novel 2-D and 3-D lightweight shape morphing structures is introduced. A fully reversible flexural shape changing cell utilizing opposing one-way shape memory alloy (SMA) actuators is shown to require no spring-like bias elements. The SMA actuating elements are arranged such that the actuation (contraction) of one of them stretches the other one in the cell, preparing it to be actuated later to reverse a flexural displacement. This antagonistic operation allows fully reversed cyclic operation. The focus of this paper is an assessment of performance at the single cell level. The cell logically provides four possible configurations in different stages of its cycle. Two of them are of particular interest because they provide two different fixed shapes for the cell that can be maintained without the continuous supply of external energy. The final deformations of the cell and equilibrium stresses in the SMA elements depend on the amount of stored shape memory strain in each element, external forces and cell geometry. A model is developed, which allows a full characterization of the AFC. The model is used to study NiTi SMA-based AFCs and the results are therefore directly applicable to the design of shape morphing structures using such unit cells.

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Kabova, Yu O., et O. A. Kabov. « Heater Size Effect on 3D Liquid Film Flow ». Dans ASME 2007 5th International Conference on Nanochannels, Microchannels, and Minichannels. ASMEDC, 2007. http://dx.doi.org/10.1115/icnmm2007-30095.

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Thin liquid films may provide very high heat transfer intensity and may be used for cooling of microelectronic equipment. Investigation of the influence of size of hot spots on 3-D structures, occurring at the film surface, is the main objective of the present work. Calculations were carried out for a rectangular heater of different width. It was obtained that there is a heater size effect on 3D liquid film deformations. Film pattern changes in spanwise direction with the heater size. Calculations have been done for various liquid Reynolds numbers.

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Molinari, G., M. Quack, A. F. Arrieta, M. Morari et P. Ermanni. « Design and Realization of a Compliant Adaptable Wing ». Dans ASME 2014 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/smasis2014-7531.

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This paper presents the design, optimization, realization and testing of a novel wing morphing concept based on compliant structures actuated by Macro Fiber Composites. The geometry of the compliant morphing ribs is determined through multidisciplinary optimizations. The static and dynamic behavior of the wing, and the effect of activating the actuators, is assessed using 3-D aeroelastic simulations. The performance and manufacturability of a wing designed according to this approach are investigated. The achieved active deformations produce sufficient roll control authority to replace conventional ailerons. The numerical simulation for the conformal shape adaptation of the wing is compared to experimental results, showing good agreement. The aerodynamic and structural behavior of the introduced concept is investigated through a validated finite element model, revealing the potential of the presented morphing wing. A closed-loop controller driving high-voltage electronics counteracts the nonlinearity and hysteresis of the piezoelectric actuators, allowing for controlling the wings’ morphing level.

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Samadani, S., A. A. Aghakouchak et J. Mirzadeh Niasar. « Nonlinear Analysis of Offshore Platforms Subjected to Earthquake Loading Considering the Effects of Joint Flexibility ». Dans ASME 2009 28th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2009. http://dx.doi.org/10.1115/omae2009-79851.

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In a conventional method of structural analysis, for modeling and analysis of jacket type offshore platforms, member connections are assumed to be rigid. In this method, members are rigidly connected which means there is no axial or rotational deformation at the end of brace member relative to chord axis. However in reality local deformations occur at chord surface due to applied loads from braces, which mean tubular joints are considerably flexible especially in non linear range of deformations. Therefore results of analysis based on rigid connections assumption differ from real behavior of the structure. Various research works have been carried out in the past on tubular joints and different methods have been presented in order to include the effect of joint flexibility in structural analysis. Most of these methods are just valid in elastic range but some non-linear methods have also been developed for simple tubular joints. In order to carry out a nonlinear analysis on a 3-D model of an offshore platform with multi-brace / multi-planar tubular joints, none of these simplified methods is applicable. In this case a complete model of tubular joints by non-linear shell elements is the most accurate one which is not only valid for non-linear analyses but also covers all type of tubular joints. In this paper two samples of offshore platforms are studied. These platforms are modeled using the following approaches: 1. No modeling of joints as structural elements (rigid connections). 2. Modeling of joint can with nonlinear shell elements (flexible connection). Different types of static non-linear analysis (Push over) are carried out and results are compared. In order to evaluate the results and compare this type of modeling with simplified methods included in professional software for the analysis of offshore structures, aforementioned platforms are also analyzed using the Fessler and MSL models to include effects of joint flexibility. The results of these types of modeling are also compared with the previous ones.

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Karadeniz, H. « A Calculation Model for Deteriorated Members of 3D Frame Structures in the Static and Dynamic Analyses ». Dans ASME 2010 29th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2010. http://dx.doi.org/10.1115/omae2010-20971.

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Jacket type structures in offshore structural industry consist of a large number of tubular members with various dimensions, which are joined to each other by welding that makes connections to be rigid. Diagonal members have relatively small dimensions, legs or chords have larger dimensions in general. Although the connections at joints are made rigidly, the actual joint behaviors under wave loadings are not fully rigid in the vicinity of connections due to local deformations of members having large diameters. In the short term, due to ultimate wave and earthquake loadings, some plastic deformations can also occur in members at some critical joints so that related members cannot be behave as rigidly connected and some releases of member forces occur. In the long term, fatigue damages can be observed at some joints that damaged members loose their functionality partly or fully as depending on damage rates. All these phenomena can be considered as member deterioration. A special treatment of deteriorated members can be used in the structural analysis by using a computation model that allows flexibility of damaged members at joints. The solution of this problem can be achieved by introducing a fictitious member concept, which can be derived as depending on actual member dimensions and joint configurations. The technique of using fictitious members introduces additional degrees of freedom that are not desirable in the analysis. A procedure which uses modified stiffness and mass matrices for flexibly connected members are more practical and attractive since a) no additional degrees of freedom are introduced, b) member-release and fixed-connection conditions can be directly obtained, c) a general member-end condition in any direction can be easily specified, d) a failure mechanism can be easily determined, e) in the fatigue damage calculation the load carrying capacity of the member can be used until the whole member cross-section is damaged and f) natural frequencies and mode shapes of damaged structural system can be estimated in terms of the natural frequencies and mode shapes of the undamaged structural system. The paper introduces a general formulation of a partly connected member to be used in structural analysis. For this purpose, a spring-beam element is defined using massless spring systems at member ends. An algorithmic procedure is presented to update member stiffness and mass matrices as well as member consistent load vector.

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Lappin, Joseph S., Warren D. Craft, Steven T. Tschantz et Changnian Sun. « Visual motion and stereo signals for a 3-D shape ». Dans OSA Annual Meeting. Washington, D.C. : Optica Publishing Group, 1991. http://dx.doi.org/10.1364/oam.1991.fm5.

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Spatial derivatives of moving and/or stereoscopic images constitute information about the differential structure of surfaces in 3-D. To investigate the role of such image properties, we have evaluated the visibility of spatial differential structure in both moving and stereoscopic images. The general method involves examining the effects of rapid random transformations of the 2-D images (translations, dilations, and 2-D and 3-D rotations) on detections and discriminations of 3-D surface structure. In stereoacuity experiments such transformations have been applied independently to the monocular half-images prior to binocular combination. Results of experiments on both structure from motion and stereoacuity indicate that (a) vision is very sensitive to the image deformations that carry information about surface shape, and (b) these deformation components can be visually distinguished from other differential components that have the same effects on the image motions and binocular disparities of both individual points and pairs of points. Thus, vision seems to be sensitive to the local differential structure of moving images—a four-parameter property, supported by relations among at least five neighboring image points.

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Wu, Jian, et Kwangyoen Wohn. « Recovering 3-D Motion and Structure from 1st-Order Image Deformation ». Dans Cambridge Symposium_Intelligent Robotics Systems, sous la direction de David P. Casasent. SPIE, 1987. http://dx.doi.org/10.1117/12.937727.

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Valenti, Justin D., Joseph Barolai, Julia A. Cole et Michael A. Yukish. « Additive Manufacturing Process-Induced Wing Skin Deformation and Effects on Aerodynamic Performance ». Dans ASME 2022 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/imece2022-96569.

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Abstract The objective of this study is to characterize the trade space for the structural design of small uncrewed aerial vehicle wings fabricated using Material Extrusion Additive Manufacturing, specifically the trade-off between maintaining the wing external shape while minimizing its internal structure. Beam bending analysis shows that the structural requirements associated with flight loads are easily met with a single perimeter extrusion monocoque construction, however this approach leads to large, unsupported, thin-walled structures that can deform during the build process, creating a potential need for additional structure to maintain wing shape. To characterize the relationship between structure/weight and wing deformation, wing sections were fabricated with varying internal structures for two airfoil shapes. Weight and 3-D laser measurements were taken of the printed parts to capture the final as-built geometry. The as-built geometries were then compared to the as-designed geometries to quantify the deformation, and a coupled viscous-inviscid flow solver was used to determine the aerodynamic effects. The results indicate that while significant aerodynamic performance penalties exist for the monocoque construction, a small amount of well-placed internal structure provides sufficient improvement at minimal weight penalty. Results also showed that less internal structure is required to minimize deformation for an airfoil with larger initial curvature.

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