Numerical Methods for the Design and Analysis of Hybrid Structures

Dieringer, Falko; Philipp, Benedikt; Wüchner, Roland; Bletzinger, Kai‐Uwe

doi:10.1260/0266-3511.28.3-4.149

Cited by 11 publications

(13 citation statements)

References 10 publications

(14 reference statements)

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“…Es wurde ein Interface zwischen der CAD‐Umgebung Grasshopper für Rhino3d und dem FE‐Rechenkern Carat++ geschaffen. Strukturen können hier in linearen und geometrisch nichtlinearen, statischen Analysen evaluiert werden oder über die Updated Reference Strategy mit einer Analyse formgefunden werden. Die Einbindung in einen Optimierungsprozess ist auch möglich.…”

Section: Vorteile Für Den Entwurfsprozessunclassified

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CAD‐integrierte Analyse im Entwurfsprozess

et al. 2019

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Leichtbau ist geprägt von seiner filigranen Tragstruktur, die sich durch eine Vielfalt von grazilen Formen und organisch wirkenden Freiformflächen auszeichnet. Moderne CAD‐Systeme nutzen NURBS (Non‐uniform rational B‐Splines), um die Formsprache des Leichtbaus dem Computer zugänglich zu machen. Die isogeometrische B‐Rep‐Analyse (IBRA) verwendet NURBS für das Lösen strukturmechanischer Probleme. Durch die Nutzung der gleichen geometrischen und topologischen Beschreibungen wird der kontinuierliche Datenaustausch zwischen CAD‐ und Analyse‐Software vereinfacht. Die einheitliche Modellbeschreibung begünstigt parametrische Entwurfsprozesse. Vorteile ergeben sich auch dort, wo die Ergebnisse einer Analyse wieder in das CAD übertragen werden sollen; beispielsweise bei einer Baufortschrittsmodellierung oder einer Formfindung, wenn es darum geht, die berechneten Geometrien erneut in den Entwurfsprozess einzubinden und mit ihnen weiterzuarbeiten. Im Hinblick auf biegeaktive Strukturen spielen die Glattheit der Modellgeometrie und die Abbildung ihrer Verformung eine bedeutende Rolle. Durch die Verwendung von NURBS ist dies gegeben.

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“…Mithilfe der CAD‐integrierten Analyse kann ein Membrantragwerk von der Formfindung bis zum Zuschnitt analysiert werden, ohne die CAD‐Umgebung zu verlassen. Im Folgenden wird die Formfindung mit der Updated Reference Strategy gezeigt.…”

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CAD‐integrierte Analyse im Entwurfsprozess

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“…, 10, see Fig. 2(b), is five times the cross sectional area of the inner cables, that is,D outer = 5D inner so that the sail obtains the desired shape of equilibrium, see [17,18]. The prestress field within the sail structure is considered constant and homogeneous with magnitude n 0 = 2 × 10 8 N/m.…”

Section: Theorymentioning

confidence: 99%

Nitsche's method for form‐finding of multipatch isogeometric membrane analysis

Apostolatos

Bletzinger

Wüchner

2018

Proc Appl Math and Mech

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Membranes constitute an important category of thin-walled and in particular tensile structures [1], for which in contrast to shells their structural rigidity is obtained by means of prestress rather than relying on bending stiffness. In particular, the structures considered in this study act in pure membrane state and have no bending stiffness. A big challenge of such structures is finding the shape of static equilibrium. This is not a trivial task since not every shape under any prestress distribution or loading condition renders a static equilibrium configuration. This is even more prominent when prestressed cables are attached to the structure. To overcome this problem for general tensile structures, various types of form-finding methods were developed [2,3]. In this study, the Updated Reference Strategy (URS) [4,5] is presented in combination with multipatch isogeometric analysis [6] as discretization method. The enforcement of the continuity constraints along the common patch interfaces [7] is realized using a Nitsche-type method [8] while the results are evaluated and compared with the Penalty-based approach [9].Herein the middle sail of the olympic stadium in Munich, see Fig. 2(a), is used in order to demonstrate the efficiency and the robustness of the proposed methodology. In Fig. 2(b) the problem placement for the form-finding analysis is depicted, where the geometry is divided into five patches. Plexiglas plates of thickness h plexiglas = 7 × 10 −3 m are attached on a steel cable net along the sails surface. Assumed is that each square of characteristic length l = 75 × 10 −2 m contains 4 inner cables with diameterD inner = 1.4 × 10 −2 m which results into cross sectional area size ofÂ inner = πD 2 inner 4 = 4.9π × 10 −5 m 2 . In this way

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“…Form finding of curved structures of all kinds has been the topic of several research publications. Tensioned structures [8,4], tensegrity structures [34], gridshells [15,2,18], hybrid structures with coupled beams and membranes [14,35] and actively curved thin shell structures [28,22] are some examples of such curved complex structures among others. Each time simplified mechanics-based procedures have been proposed to deal with nonlinear equations of the formfinding problem with a focus on robustness and efficiency.…”

Section: Related Workmentioning

confidence: 99%

Form-Finding of Interlaced Space Structures Using Constrained Nonlinear Optimization

Nabaei

Baverel

Weinand³

2015

International Journal of Space Structures

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The term Interlaced Space Structures (ISS) corresponds to a coupled system of naturally curved flexible panels/strips interlaced together according to a design pattern. The goal of the present study is to look for a physically-based and efficient form-finding procedure in order to interactively explore different interlaced morphologies with respect to the design parameters for structural design purposes. Each panel is considered as an in-extensible discrete kirchhoff rod and the rest shape of the coupled system rods is obtained via a constrained total energy minimization. The interlacing pattern is translated into a set of overlap order constraints and applied to the optimization problem. An implementation of the interior-point filter linesearch algorithm with the Quasi-Newton procedure has been employed to solve the constrained nonlinear optimization. The approach is then discussed and commented in detail through a number of form-finding case studies.

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Numerical Methods for the Design and Analysis of Hybrid Structures

Cited by 11 publications

References 10 publications

CAD‐integrierte Analyse im Entwurfsprozess

CAD‐integrierte Analyse im Entwurfsprozess

Nitsche's method for form‐finding of multipatch isogeometric membrane analysis

Form-Finding of Interlaced Space Structures Using Constrained Nonlinear Optimization

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