PSI - Issue 24

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ScienceDirect

Procedia Structural Integrity 24 (2019) 593–600 Structural Integrity Procedia 00 (2019) 000–000 Structural Integrity Procedia 00 (2019) 000–000

www.elsevier.com / locate / procedia www.elsevier.com / locate / procedia

AIAS 2019 International Conference on Stress Analysis Bistable morphing panels through SMA actuation Riccardo Panciroli a, ∗ , Francesca Nerilli a a Niccolo` Cusano University, via don Carlo Gnocchi 3, 00166, Rome, Italy AIAS 2019 International Conference on Stress Analysis Bistable morphing panels through S A actuation Riccardo Panciroli a, ∗ , Francesca Nerilli a a Niccolo` Cusano University, via don Carlo Gnocchi 3, 00166, Rome, Italy

© 2019 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) Peer-review under responsibility of the AIAS2019 organizers Abstract This work introduces a numerical solution scheme for the prediction of the morphing mechanism in smart composite structures. Morphing relies on bistable plates actuated through nitinol shape memory wires. Bistable panels are obtained by exploiting the anisotropic thermal expansion of anti-symmetric composite laminates, which directly influences the post-cured shape. The numerical model accounts for the thermal distortions introduced upon cooling of the laminate as a result of the production process, and for the shape memory behavior of nitinol wires. The stress-strain behavior of the nitinol wire has been evaluated experimentally and implemented in the numerical model. A bistable composite plate has been manufactured for the purpose and results about its post-cured curvature have been utilized to tune the numerical model. The verified numerical scheme has been finally utilized to investigate the possibility to morph the panels by exploiting the actuation capabilities of Nitinol wires through thermal activation. Particular interest has been devoted to the analysis of prestrain, dimension, position, and the number of wires to cyclically actuate the panel. The numerical model can serve as tool to highlight the role of plate dimension, material properties, lamination sequence, and thermal cycle on the post-cured stable configurations, and for the identification of number and location of wires to best perform the morphing cycle. c 2019 The Authors. Published by Elsevier B.V. is is an open access article under the CC BY-NC-ND license (http: // creativecommons.org / licenses / by-nc-nd / 4.0 / ) P er-review line: Peer-review und r responsibility of the AIAS2019 organizers. Keywords: Bistable plates; Shape memory wires; Thermal stresses; Actuation Abstract This work introduces a numerical solution scheme for the prediction of the morphing mechanism in smart composite structures. Morphing relies on bistable plates actuated through nitinol shape memory wires. Bistable panels are obtained by exploiting the anisotropic thermal expansion of anti-symmetric composite laminates, which directly influences the post-cured shape. The numerical model accounts for the thermal distortions introduced upon cooling of the laminate as a result of the production process, and for the shape memory behavior of nitinol wires. The stress-strain behavior of the nitinol wire has been evaluated experimentally and implemented in the numerical model. A bistable composite plate has been manufactured for the purpose and results about its post-cured curvature have been utilized to tune the numerical model. The verified numerical scheme has been finally utilized to investigate the possibility to morph the panels by exploiting the actuation capabilities of Nitinol wires through thermal activation. Particular interest has been devoted to the analysis of prestrain, dimension, position, and the number of wires to cyclically actuate the panel. The numerical model can serve as tool to highlight the role of plate dimension, material properties, lamination sequence, and thermal cycle on the post-cured stable configurations, and for the identification of number and location of wires to best perform the morphing cycle. c 2019 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http: // creativecommons.org / licenses / by-nc-nd / 4.0 / ) Peer-review line: Peer-review under responsibility of the AIAS2019 organizers. Keywords: Bistable plates; Shape memory wires; Thermal stresses; Actuation

1. Introduction 1. Introduction

Bistable structures are attracting an increasing attention in the recent years because of the recent developments in smart materials, such as piezoelectrics and shape memory alloys (SMA). The integration of smart materials within bistable structures allows to develop a smart structure which can serve not only for actuation purposes (Giddings et al., 2008), but also for energy harvesting (Betts et al., 2013a; Emam and Inman, 2015). A large energy content is in fact involved during the snap-through between two stable configurations. Energy harvesting is commonly attained by integrating piezoelectrics into the bistable structure, while for shape morphing both piezoelectrics or SMAs can be utilized (Mohd et al., 2014; Niturkar and Gaikwad, 2016). Bistable structures are attracting an increasing attention in the recent years because of the recent developments in smart materials, such as piezoelectrics and shape memory alloys (SMA). The integration of smart materials within bistable structures allows to develop a smart structure which can serve not only for actuation purposes (Giddings et al., 2008), but also for energy harvesting (Betts et al., 2013a; Emam and Inman, 2015). A large energy content is in fact involved during the snap-through between two stable configurations. Energy harvesting is commonly attained by integrating piezoelectrics into the bistable structure, while for shape morphing both piezoelectrics or SMAs can be utilized (Mohd et al., 2014; Niturkar and Gaikwad, 2016).

2452-3216 © 2019 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) Peer-review under responsibility of the AIAS2019 organizers 10.1016/j.prostr.2020.02.052 ∗ Corresponding author. Tel.: + 39 3407793659 E-mail address: riccardo.panciroli@unicusano.it 2210-7843 c 2019 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http: // creativecommons.org / licenses / by-nc-nd / 4.0 / ) Peer-review line: Peer-review under responsibility of the AIAS2019 organizers. ∗ Corresponding author. Tel.: + 39 3407793659 E-mail address: riccardo.panciroli@unicusano.it 2210-7843 c 2019 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http: // creativecommons.org / licenses / by-nc-nd / 4.0 / ) Peer-review line: Peer-review under responsibility of the AIAS2019 organizers.