On the use of thermomechanical couplings for the design of adaptive structures

Thermomechanical couplings are responsible for the smart behavior of Shape Memory Polymers (SMPs). Additionally to the shape memory effect, the strong and fast glass transition in this kind of material is directly related to radical changes in the storage modulus and loss factor of the material. When integrated into composite structures, these materials can be used to change in real time the global stiffness and structural damping. This type of strategy opens new ways for vibration control which are currently investigated at FEMTO-ST institute. Several applications of this concept are described, corresponding to various scales and frequency ranges. For each of them, the design strategy based on finite element analysis is shown, taking advantage of thermomechanical couplings to describe the various behaviors of the composite. Then, the prototypes are manufactured and tested. Various complexity levels in the thermal fields are obtained through regulation, from homogeneous to gradient or even heterogeneous so that many structural behaviors can be obtained and changed in real time. Illustrations are shown on sandwich panels, phononic crystals and acoustic black holes. Open challenges are finally discussed.