Vibrational Properties of a Hemispherical Shell With Its Inner Fluid Pressure: An Inverse Method for Noninvasive Intracranial Pressure Monitoring

Vibration due to a hammer impact on an aluminum hemisphere fully filled with water is determined to study the frequency response of the structure at different inner fluid pressures. Modal analysis techniques are utilized on the frequency response function (FRF) to extract the modal frequencies and the damping ratios at each pressure level. As fluid pressure increases, changes to the peaks of frequency response are observed. Due to this, modal frequencies will also undergo some shifts with changes in the repeated poles of frequency response. Changes can also be observed in singular bending wave modes. An inverse analysis of such changes due to inner pressure in modal frequencies of the structure can make a possible method for using vibrational stimulus and response in a noninvasive intracranial pressure (ICP) monitoring system.