Evolution of ultrasonic impulses in chains of spheres using resonant excitation

D. A. Hutchins, J. Yang, O. Akanji, P. J. Thomas, L. A. J. Davies, S. Freear, S. Harput, N. Saffari, P. Gelat
2015 Europhysics letters  
PACS 43.35.+d -Acoustics: Ultrasonics, quantum acoustics, and physical effects of sound PACS 46.40.-f -Vibrations and mechanical waves PACS 45.50.-j -Dynamics and kinematics of a particle and a system of particles Abstract -It is demonstrated that broad-bandwidth ultrasonic signals containing frequency components in excess of 200 kHz can be created in spherical chains using harmonic excitation at 73 kHz. Multiple reflections created a periodic waveform containing both harmonics and subharmonics
more » ... cs and subharmonics of the original forcing frequency, due to non-linear Hertzian contact. These discrete frequencies represented some of the many allowed non-linear normal modes of vibration of the whole chain. Excitation at a single fixed frequency could thus be used to produce wide-bandwidth impulses for different lengths of spherical chains. Experimental results were in good agreement with theoretical predictions. open access
doi:10.1209/0295-5075/109/54002 fatcat:mfalok7yt5hc7dyomqxkpwhh6m