Underlying mechanics of active nanocomposites with tunable properties

This paper proposes the development of a new class of nanotube-based piezoelectric polymeric composites with controllable bond expansion and contraction in the interface of nanotube and matrix for use in next-generation structural vibration control systems. It is theoretically shown that through applying external electrical field, the quality of adhesion between nanotube and the matrix at nanoscale can be imparted to result in novel engineered composites at macroscale with tunable mechanical properties ranging from stiffer structure to better damper, the attributes that are essential for structural vibration control. Along this line, two classes of nanotubes; namely, carbon nanotubes (CNTs) and boron nitride nanotubes (BNNTs), are investigated. It is demonstrated that BNNTs possess better tunability compared to CNTs due to their outstanding molecular crystalline structure. More specifically, it is shown that mechanical properties of BNNT-based structures are more sensitive to the variation of separation distance in the interphase zone, and the stick-slip mechanism, which is responsible for damping change, can easily occur in BNNT-reinforced piezoelectric polymers.