Chirality, a fundamental property of matter, has long been associated with the optical activity (wave polarization rotation) of chiral objects. However, its development in the mechanical/acoustical domain has been comparatively limited, due to persistent challenges in both the characterization of chiral mechanical effects and the fabrication of chiral mechanical materials.
We have recently developed a stroboscopic imaging system capable of characterizing the polarization of transverse mechanical waves. Using this system, we investigated chiral composites fabricated from twisted carbon nanotube (CNT) fibers. Remarkably, we observed substantial polarization rotation of transverse mechanical waves, exceeding ±90° for left-handed and right-handed composites. The mechanical rotation effects were systematically studied by varying the structural parameters of the composites. The experimental results showed good agreement with theoretical predictions based on acoustic band structure analysis and finite element modeling.
