01815nas a2200145   4500008004100000245005800041210005800099300001300157490000800170520135300178100001901531700002201550700002701572856007001599       2022                        eng d00aOptimal design of planar shapes with active materials0 aOptimal design of planar shapes with active materials  a202202560 v4783 a<p>Active materials have emerged as valuable candidates for shape morphing applications, where a body reconfiguration is achieved upon triggering its active response. Given a desired shape change, a natural question is to compare different morphing mechanisms to select the most effective one with respect to an optimality criterion. We introduce an optimal control problem to determine the active strains suitable to attain a target equilibrium shape while minimizing the complexity of the activation. Specifically, we discuss the planar morphing of active, hyperelastic bodies in the absence of external forces and exploit the notion of target metric to encompass a broad set of active materials in a unifying approach. For the case of affine shape changes, we derive explicit conditions on the body reference configuration for the optimality of homogeneous target metrics. More complex shape changes are analysed via numerical simulations to explore the impact on optimal solutions of different objective functionals inspired by features of existing materials. We show how stresses arising from incompatibilities contribute to reduce the complexity of the controls. We believe that our approach may be exploited for the optimal design of active systems and may contribute to gather insight into the morphing strategies of biological systems.</p>1 aAndrini, Dario1 aNoselli, Giovanni1 aLucantonio, Alessandro  uhttps://royalsocietypublishing.org/doi/abs/10.1098/rspa.2022.025601464nas a2200157   4500008004100000022001400041245007900055210006900134260000700203490000700210520098300217100001901200700002701219700002201246856003801268       2020                        eng d  a0021-893600aA Theoretical Study on the Transient Morphing of Linear Poroelastic Plates0 aTheoretical Study on the Transient Morphing of Linear Poroelasti  c120 v883 a<p>Based on their shape-shifting capabilities, soft active materials have enabled new possibilities for the engineering of sensing and actuation devices. While the relation between active strains and emergent equilibrium shapes has been fully characterized, the transient morphing of thin structures is a rather unexplored topic. Here, we focus on polymer gel plates and derive a reduced linear model to study their time-dependent response to changes in the fluid environment. We show that independent control of stretching and bending deformations in stress-free conditions allows to realize spherical shapes with prescribed geometry of the mid-plane. Furthermore, we demonstrate that tensile (compressive) membrane stresses delay (accelerate) swelling-induced shape transitions compared to the stress-free evolution. We believe that these effects should be considered for the accurate design of smart systems and may contribute to explain the complexity of natural shapes.</p>1 aAndrini, Dario1 aLucantonio, Alessandro1 aNoselli, Giovanni  uhttps://doi.org/10.1115/1.4048806