Improving damping capabilities of composites structures by electroactive films containing piezoelectric and conductive fillers

In this paper, a passive vibration damping concept based on multifunctional materials was studied for thermoplastic composite structures. The synergy between piezoelectric and conductive particles brings a new contribution of energy dissipation based on the local transduction-dissipation phenomenon. While piezoelectric fillers ensure the conversion of mechanical energy into electrical energy (transduction), conductive particles locally dissipate the electric charges created avoiding saturation in the vicinity of piezoelectric particles. Here, the concept has been studied at material and structure scales for laboratory and preindustrial samples in order to bring solid proof of the damping concept. For this purpose, piezoelectric and electrically conductive particles were dispersed into engineering thermoplastics polyamide 12 and poly ether ketone ketone. Damping films were obtained by hot press and embedded in a composite sandwich beam and carbon fiber reinforced polymer (CFRP)-aluminum panels. Dynamic mechanical analysis and vibration tests were performed on bulk nanocomposite samples and in composite sandwich beams. The study of hysteresis loops and frequency response function showed strong nonlinear effects and vibration amplitude decrease up to 50%. Tests on CFRP-aluminum panels highlighted the structural damping increase demonstrating the potential capacity of this multifunctional material for energy dissipation in typical aerospace structures.