### ASA 128th Meeting - Austin, Texas - 1994 Nov 28 .. Dec 02

## 3aPAb11. A model for cavitation damage during ultrasonic cleaning.

**Quan Qi
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John G. Harris
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Robert E. Johnson
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*Dept. of Theor. and Appl. Mech., Univ. of Illinois at Urbana-Champaign,
216 Talbot Lab., 104 S. Wright St., Urbana, IL 61801
*

*
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A model is proposed in this report to describe the potential growth of an
existing crack in the structural component caused by collapsing bubbles during
ultrasonic cleaning. A local pressure rise is generated by the collapse of a
single bubble and the momentum of the collapse is described by the Kelvin
impulse I(t). By assuming a uniform pressure distribution and using dynamic
fracture mechanics, we obtain a simple relation that expresses the dynamic
stress intensity factor K(t) as a function of the Kelvin impulse. Further
simplification is achieved by assuming spherical bubble deformation in the
description of the Kelvin impulse, as suggested by Blake and Gibson [Ann. Rev.
Fluid Mech. 19, 99--123 (1987)], and this leads to a relation between the
dynamics of a single bubble and the stress intensity factor K(t). The time
history of K(t) is discussed for a completely collapsed bubble obeying the
Rayleigh equation. Once the dynamical stress intensity factor exceeds the
fracture toughness K[sub IC] crack will start to grow. Repeated action of
collapsing bubbles eventually leads to the failure of the component. [Work
supported by the Manufacturing Research Center of the University of Illinois.]

All posters will be on display from 8:00 a.m. to 12:00 noon. To allow
contributors an opportunity to see other posters, contributors of odd-numbered
papers will be at their posters from 8:00 to 10:00 a.m. and contributors of
even-numbered papers will be at their posters from 10:00 a.m. to 12:00 noon.
Posters will remain on display until 5:00 p.m.