reports that engineers at NASA’s Jet Propulsion Laboratory have developed an ultrasonic jackhammer (USJ).
A small-scale prototype of the jackhammer has been built, and its developers say that a fully developed, full-scale version could be used for cutting through concrete, rocks, hard asphalt, and other materials.
In the USJ, a piezoelectric stack is electrically driven at its resonance frequency which causes a free mass to bounce between hard stops. Its impact on the stops then creates pulses that propagate along a horn, to and through the tool bit.
A conventional pneumatic jackhammer generates enormous amounts of noise, along with severe vibrations that propagate back into the operator’s body. Sometimes, they are so great that they injure the operator. What is more, every object encountered by the tool bit is damaged.
In contrast, a full-scale USJ would generate much less noise and much less back-propagating vibration. It would also use less power.
Moreover, the developers say that relatively flexible materials as wood, plastics, metals and even human tissue would not be damaged by brief contact with the tool bit of the operating USJ.