Title

Development of a computer model for investigating the effects of internal pressure on the resonance of spherical shells

Presenter Information

Drake Mith
Sami Abdul-Wahid

Document Type

Oral Presentation

Location

SURC 137A

Start Date

17-5-2012

End Date

17-5-2012

Abstract

A computational model of a fluid-filled spherical aluminum shell is used to investigate how the resonance frequency of the shell responds to an increase in internal pressure. The model is created using COMSOL, which is a finite-element solver that allows the user to specify the geometry and the physics of the system. An important feature of COMSOL is that multiple physical processes can be combined in one problem. In the present case, a two-stage approach is followed: first, the hydrostatic pressure inside the shell is specified and a static solution is obtained for the resulting stresses and strains within the shell; these values are then used as inputs to the second stage, in which the pattern and amplitude of shell vibration is computed for a range of excitation frequencies. The result is a response curve, which shows how vibration amplitude depends on frequency. A response curve is generated for several values of the internal pressure. Results are compared to laboratory measurements, which show a shift in the response peaks towards higher frequencies as the internal pressure is increased. The goal is to develop a reliable method for noninvasively assessing changes in intracranial pressure.

Faculty Mentor(s)

Andy Piacsek

Additional Mentoring Department

Physics

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May 17th, 4:30 PM May 17th, 4:50 PM

Development of a computer model for investigating the effects of internal pressure on the resonance of spherical shells

SURC 137A

A computational model of a fluid-filled spherical aluminum shell is used to investigate how the resonance frequency of the shell responds to an increase in internal pressure. The model is created using COMSOL, which is a finite-element solver that allows the user to specify the geometry and the physics of the system. An important feature of COMSOL is that multiple physical processes can be combined in one problem. In the present case, a two-stage approach is followed: first, the hydrostatic pressure inside the shell is specified and a static solution is obtained for the resulting stresses and strains within the shell; these values are then used as inputs to the second stage, in which the pattern and amplitude of shell vibration is computed for a range of excitation frequencies. The result is a response curve, which shows how vibration amplitude depends on frequency. A response curve is generated for several values of the internal pressure. Results are compared to laboratory measurements, which show a shift in the response peaks towards higher frequencies as the internal pressure is increased. The goal is to develop a reliable method for noninvasively assessing changes in intracranial pressure.