A morphing metastructure concept combining shape memory alloy wires and permanent magnets for multistable behavior

Abstract

This article presents a novel morphing unit cell concept which relies on the combination of shape memory alloy wires for actuation and permanent magnets to enable multistability. Two distinct applications are investigated experimentally, consisting in a morphing beam metastructure made with three unit cells and a variable camber airfoil metastructure having six unit cells in the chord-wise direction. Tests are performed to assess the influence of the permanent magnets on the morphing behavior of the two referred metastructures. It is verified that the permanent magnets are able to provide new stable equilibrium configurations to the metastructure and to reduce the time necessary for morphing. Another interesting feature, which enables the reduction in energy consumption, is that, due to the magnetic interactions, the thermal activation of the SMA wires can be ceased once an equilibrium configuration is achieved. The paper describes the design premises, evaluates its limitations and devises future improvements.

Avian-inspired wing sweep

“…To perform sweep, one might put a joint in the wing, inspired by birds, and sweep with an electric motor at the joint. Here we examine a distributed sweep using a unique shape memory alloy approach assemble in cells following [3] who first used this approach to change wing camber. These cells illustrated in Figure1.…”

Research on hierarchical cylindrical negative stiffness structures’ energy absorption characteristics

“…NS structures are a class of mechanical metamaterials that have gained significant attention due to their reusability [1][2][3][4] and potential applications in various fields, such as vibration control [5][6][7][8][9][10][11][12][13], energy absorption [4,[14][15][16][17][18][19][20][21], and actuation [22][23][24][25][26][27][28][29][30][31]. It is of particular importance in the area of energy absorption, as it can absorb energy through its multistable property [32][33][34][35][36][37][38][39] and dissipate it with a snap-back behavior [7,35,[40][41][42][43][44], rather than through plastic deformation…”