Multilayer Radical Morphing: Shape Transitions and Vibration

Shape-shifting materials are entering into many disciplines from engineering to medicine where passive sensors are needed. Within this field, having materials which could automatically and cyclically reconfigure their shape in response to the surrounding environment while maintaining their performance during their in-service life is of great interest and challenging. Here, an experimental study is performed to analyze the cyclic morphing capabilities and the dynamic response of a unique multilayer system that changes shape in a pre-defined and, indeed, tunable temperature range which is triggered by an unconventional training. The material is formed by a composite of polyethylene (PE) film reinforced with polyethylene terephthalate (PET) fibers sandwiched with an aluminum layer. The results highlight the great capability of the material to spontaneously morph from a flat to a rolled shape when exposed to pre-set thermal gradients while maintaining a nearly constant frequency response. This result is due to a mutual compensation of material, structural, and geometric properties acquired in different configurations.