Vehicle Propulsion by Solid State Motion

Traveling waves have shown the potential to transport material and are thus investigated as a propulsion mechanism. Through the use of piezoelectric actuators (PZTs), traveling waves were produced in beams with both free-free and fixed-free boundary conditions. It is shown that traveling waves can be generated by exciting two PZTs at a common frequency with a phase difference between the PZT signals. Experimentation showed the signal that creates the best traveling wave occurs at a driving frequency halfway between adjacent bending resonance frequencies and a phase difference of 90° between both PZTs signals. This has produced traveling waves in fixed-free beams and free-free beams in both air and water as well as for an underwater vehicle. These traveling waves generated useful propulsion in both the fixed-free and free-free beams.