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Reviews of published papers and articles on power ultrasonics

Ultrasonic Motor Development

11 August, 2004 - 14:00 — Chris

(Now updated with a new link to NASA Telerobotics Program Plan, since the old page has been removed.)

An interesting page about research at MIT to develop a high torque-density solid-state actuator for use in the NASA/JPL Mars Micro Lander manipulator arm. It includes a general explanation of the principles of ultrasonic motors, and some cool animations! Note the use of dynamic and time-averaged ESPI (electronic speckle pattern interferometry) to evaluate the vibration modes.

Canon Ultrasonic Motors (USMs)

11 August, 2004 - 14:00 — Chris

(Link updated March 2008)

Canon's brief description of their development of ultrasonic motors for use in camera auto-focus lenses. Their explanation of the arrangement of piezoelectric elements is particularly good. There are two sets of elements, offset by a quarter-wavelength, each generating a standing wave. Superimposing the offset standing waves creates a traveling wave that drives the rotor.

AEA Technology Sonocrystallizer

11 August, 2004 - 14:00 — Chris

(Link updated March 2008)

The AEA Technology Sonocrystallizer (TM) is a new reactor which produces better crystals for the pharmaceutical and bio-tech industries. For more details see the July 2000 newsletter.

Theory of ultrasonic metal welding

11 August, 2004 - 14:00 — Chris

(Link updated Jan 2007)

The subject of metal welding seems to attract high-quality articles from equipment suppliers. While not as comprehensive as Stapla's book, this article from AmTech gives a good introduction to the theory and practice of welding metals, aimed particularly at wire-joining applications.

Creating Sonoluminescence

11 August, 2004 - 14:00 — Chris

(Link updated August 2004)

Ultrasound in liquids creates cavitation bubbles, which as they collapse can generate immense temperatures and pressures, and brief faint flashes of light - called sonoluminescence. It's a strange phenomenon, not yet fully understood but very reproducible. This article gives a clear account of the equipment required to generate and study sonoluminescence - a surprisingly simple set up suitable for a high-school laboratory.

Power ultrasonic equipment for sonochemistry research.

11 August, 2004 - 14:00 — Chris

(Link updated March 2008)

John Perkins has vast experience in power ultrasonics. Here he starts with the basics, covering the design and construction of piezo sandwich transducers and sonotrodes, before giving a detailed description of sonochemistry principles - cavitation, energy-density, monitoring power and amplitude.

Ultrasonic cleaning in supercritical liquid CO2

22 June, 2001 - 14:00 — Chris

Using liquid carbon dioxide as a cleaning solvent offers some great environmental advantages. Compared to conventional chlorinated solvents and detergents it is very clean, with no harmful emissions. Separating the liquid from the dissolved contaminants is easy - just reduce the pressure and allow the CO2 to boil off (after which it can be trapped and recycled). However the pressure required to maintain CO2 in liquid form (>60 bar) does present some challenges for ultrasonic tank design...

Magneto-strictive transducers are back! (or not)

18 April, 2000 - 14:00 — Chris

Not an article as such, but hopefully of interest to readers...

Since the early 1980's, piezo-electric transducers have dominated the power ultrasonics industry. After some early reliability problems (cured largely by improvements to the electronic control systems used to drive them) they have now almost completely replaced the old inefficient laminated nickel alloy transducers wrapped in coils of PTFE insulated wire (the heat generated would melt conventional plastic insulation!).

ETREMA plans to change all that, with their new ultrasonic transducers based on Terfenol D®.