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.
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