It has been known for many years that properties of individual materials can be improved by appropriately combining two materials in a composite. A stiff and a lossy material can be joined to achieve desired combinations of Young’s modulus and damping coefficient, but fundamental mechanical considerations bound the achievable combinations. These bounds can be exceeded by invoking frictional loss at the interfaces between phases or by using negative stiffness elements. In this thesis we explore both concepts. In the first part, see section 2, we develop a technique to measure the loss coefficient of a micro-architected hollow-truss based material with and without polymer cores and unveil the role of the core on damping. In the second part, see section 3, we explore the possibility of developing stable systems with tunable combinations of stiffness and damping by employing electric fields to generate negative stiffness elements.

Outgoing