Homogenizability of Element Utilization in Adaptive Structures

Böhm, Michael; Wagner, Julia L.; Steffen, Simon; Sobek, Werner; Sawodny, Oliver

doi:10.1109/coase.2019.8843066

Cited by 17 publications

(10 citation statements)

References 17 publications

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“…Das zugrunde liegende Gütekriterium bestraft bspw. hohe Knotenverschiebungen oder eine ungleichmäßige Tragwerksauslastung [22]. Eine Methode zur Minimierung der Verformungen unter Last wurde an einem maßstäblichen (1:18) Aufbau (Bild 8) erfolgreich validiert [23].…”

Section: Systemtechnik Und Auslegungunclassified

Adaptive Hüllen und Strukturen

et al. 2021

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Die „Große Beschleunigung“ bei Bevölkerungszahlen, klimaschädlichen Emissionen, Wasserverbrauch und vielem anderen stellt die gesamte Menschheit vor große Herausforderungen. Dies trifft besonders auf das Bauschaffen zu. Es gilt, zukünftig für mehr Menschen mit weniger Material emissionsfrei zu bauen. Hierfür muss unsere Art des Planens, Bauens und Nutzens von Bauwerken neu gedacht und neu konzipiert werden. Auf der bautechnischen Seite bedeutet dies die konsequente flächendeckende Umsetzung von Leichtbaustrategien. Zu diesen zählt neben dem klassischen Leichtbau und den Gradientenbauweisen auch das Bauen mit adaptiven Hüllen und Strukturen. Unter Adaptivität sind dabei unterschiedliche Veränderungen der Geometrie, der physikalischen Eigenschaften von einzelnen Bauteilen oder von ganzen Bauwerken zu verstehen. Durch Adaption können Spannungsfelder homogenisiert, Bauteilverformungen reduziert und bauphysikalische Verhalten von Bauteilen verändert werden. All dies verringert nicht nur den Materialbedarf, sondern liefert auch einen wesentlichen Beitrag zur Steigerung des Nutzerkomforts. Adaptivität im weiteren Sinne bezeichnet einen ganzheitlichen Ansatz, in dem die Anpassung sozialer, kultureller und räumlicher Erfahrungen sowie architektonischer und planerischer Handlungsweisen eng mit den technologischen Entwicklungen verknüpft wird. Die Zusammenführung dieser Perspektiven ist Anspruch des SFB, um ganzheitliche Lösungen für eine zukünftige gebaute Umwelt zu finden.

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Section: Systemtechnik Und Auslegungunclassified

Adaptive Hüllen und Strukturen

et al. 2021

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“…Another possible optimization metrics is the homogenization of element forces over all elements, which was used as a metric for actuator placement by Böhm et al (2019). For this, the stress in an element is calculated and set in relation to its yield strength.…”

Section: Optimization Metricmentioning

confidence: 99%

“…Previous works of our group have considered the problem of actuator placement for structures under static loads (e.g., Wagner et al, 2018;Böhm et al, 2019) and under dynamic loads (e.g., Heidingsfeld et al, 2017), as well as dynamic modeling and nonlinear damping control of structures with tensiononly elements (e.g., Wagner et al, 2019a) and enhanced with decentralized control (e.g., Wagner et al, 2020). Böhm et al (2020) focus on modeling and successful integration of different types of actuation principles into existing FE-models of passive structures.…”

Section: Introductionmentioning

confidence: 99%

Optimal Static Load Compensation With Fault Tolerance in Nonlinear Adaptive Structures Under Input and State Constraints

Wagner

Gienger

Stein

et al. 2020

Front. Built Environ.

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Adaptive structures are conventional truss structures that are equipped with sensors, actuators, and a control unit. This offers the opportunity of reacting and adapting to external loads but raises nontrivial issues. When actuators are placed optimally within a structure, they can be individually integrated either parallel to or in series with elements of the original passive structure. Additionally, some of the elements might be tension-only elements and thus have to be treated as nonlinear, as their stiffness depends on the stress within the element itself. Input constraints naturally arise for actuators, e. g., due to the maximum pressure limit of a hydraulic system and displacement limits of the actuators. We present modeling approaches for an add-on inclusion of these different types of actuators in an existing finite-element model of a passive structure. We place special focus on the ability of the model to reproduce the correct behavior in case of an actuator reaching its displacement constraint within a tension-only element. When such an adaptive structure is subject to static loads, e. g., wind loads, it is required to respond using its actuators to keep the structure within given safety and comfort limits. These limits can be expressed as state constraints. We present a method for optimally compensating these static loads under the given input and state constraints along with experimental results on a scale model of an actual high-rise building. An important aspect regarding adaptive structures is that of their behavior in case of actuator faults. An obvious result is that a structure's performance degrades, and the controller needs to recognize faults and deal with it properly. Assuming a diagnosed actuator fault, we present results illustrating the performance degradation. The designed controller can reconfigure and reinitialize itself. The performance with and without applied reconfiguration to the nominal case is compared.

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“…Several systems have been studied to control the structural response including building frames equipped with active bracings/columns (Reinhorn et al, 1993;Wagner et al, 2018;Weidner et al, 2018) and variable stiffness joints as well as bridges equipped with active cable-tendons (Rodellar et al, 2002;Xu et al, 2003). Through integrated structure-control optimization (Smith et al, 1991;Begg and Liu, 2000;Soong and Cimellaro, 2009;Frohlich et al, 2019) civil structures can be designed to adapt (e.g., react positively) to rare loading events of high intensity in order to operate closer to required limits, which results in a better material utilization compared to equivalent weight-optimized passive structures (Teuffel, 2004;Sobek, 2016;Böhm et al, 2019). Material savings, however, are only possible at a cost of energy that is required to operate the adaptive system.…”

Section: Introductionmentioning

confidence: 99%

Force and Shape Control Strategies for Minimum Energy Adaptive Structures

Senatore

Reksowardojo

2020

Front. Built Environ.

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This work presents force and shape control strategies for adaptive structures subjected to quasi-static loading. The adaptive structures are designed using an integrated structure-control optimization method developed in previous work, which produces minimum "whole-life energy" configurations through element sizing and actuator placement optimization. The whole-life energy consists of an embodied part in the material and an operational part for structural adaptation during service. Depending on the layout, actuators are placed in series with the structural elements (internal) and/or at the supports (external). The effect of actuation is to modify the element forces and node positions through length changes of the internal actuators and/or displacements of the active supports. Through active control, the stress is homogenized and the displacements are kept within required limits so that the design is not governed by peak demands. Actuation has been modeled as a controlled non-elastic strain distribution, here referred to as eigenstrain. Any eigenstrain can be decomposed into two parts: an impotent eigenstrain only causes a change of geometry without altering element forces while a nilpotent eigenstrain modify element forces without causing displacements. Four control strategies are formulated: (C1) force and shape control to obtain prescribed changes of forces and node positions; (C2) shape control through impotent eigenstrain when only displacement compensation is required without affecting the forces; (C3) force control through nilpotent eigenstrain when displacement compensation is not required; and (C4) force and shape control through operational energy minimization. Closed-form solutions to decouple force and shape control through nilpotent and impotent eigenstrain are given. Simulations on a slender high-rise structure and an arch bridge are carried out to benchmark accuracy and energy requirements for each control strategy and for different actuator configurations that include active elements, active supports and a combination of both.

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Homogenizability of Element Utilization in Adaptive Structures

Cited by 17 publications

References 17 publications

Adaptive Hüllen und Strukturen

Adaptive Hüllen und Strukturen

Optimal Static Load Compensation With Fault Tolerance in Nonlinear Adaptive Structures Under Input and State Constraints

Force and Shape Control Strategies for Minimum Energy Adaptive Structures

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