May 22, 2019
Device schematic (Milner and Hutchens, fig. 1a)
A Small-scale Ballistic Cavitation (SBC) technique is available from researchers at the University of Illinois at Urbana-Champaign. A piezo actuator that would open and close in less than 5 milliseconds was required to operate the SBC. The high-speed valve dispenses pulses of air from a high-pressure chamber (up to 30 MPa or 4,300 psi) into a soft material sample. A schematic of the device is shown above.
The air pulses form cavities inside the sample that replicate the effects of ballistic damage. The figure below shows the cavities formed in the soft material sample from two different pressure levels at 0, 2 and 7 milliseconds.
Images of cavity formation (Milner and Hutchens, fig. 1b)
Researchers determined that a high-frequency piezo actuator was required to operate the valve. Solenoid actuated devices did not have the combination of sub-millisecond open/close times and ability to operate at pressure levels up to 30 MPa (Milner and Hutchens 72). The researchers at UIL Urbana-Champaign asked Dynamic Structures and Materials for an actuator to drive the benchtop testing drive. DSM coordinated with the researchers to design a custom solution. The high frequency piezo actuator, is shown in the figure below.
Custom actuator and housing
The sub-millisecond pulse time supplied by DSM’s piezo actuator allowed the researchers to build a device that modeled ballistic damage without the disadvantages of traditional ballistic testing experiments.
SBC device (Milner and Hutchens, fig. 3c)
DSM’s high frequency piezo actuator (PSA) page has datasheets for actuators similar to the one used in this testing device. DSM has recommended applications listed on the PSA page and can customize this actuator architecture for new applications.
For more information on the benchtop ballistic cavitation technique, check out the Extreme Mechanics Letters journal referenced below.
Milner, M. P. and Hutchens, S. B. “A benchtop ballistic cavitation technique,” Extreme Mechanics Letters 28 (2019) 69-75.