Vibration--Measurement

In this thesis the flow of vibration power between two coupled, finite plates of arbitrary thicknesses is considered using a Mobility Power Flow (MPF) approach. The plate structure is divided into substructures and mobility functions are determined for the independent substructures. Power flow expressions are derived based on continuity of forces and displacements. The solution presented here considers the effects of both in-plane waves and out-of-plane waves. The solution is applicable to frequencies below the first mode of thickness-shear vibration. The results obtained show that at low frequencies, the out-of-plane waves dominate in the transmission of vibrational power. However, at high frequencies or for thick plates, the in-plane waves play a significant role in the power transmission through the plate.

Modal analysis testing techniques were used to determine
the modal parameters and mode shapes for flexural vibration of a
Fiberizer Discmill disc to help define a safe operating speed range.
The modal parameters and mode shapes were determined for the
first six diametral modes, the first concentric mode, and the first
rigid body shaft mode. The disc consisted of a circular aluminum
plate with eight equally and symmetrically spaced radial cutters on
one face of the disc and eight equally spaced peripheral cutters
located on the rim of the disc midway between the angular locations
of the radial cutters. All cutters were of tool steel. The
safe area of operation is determined to be between 3000 rpm and
3600 rpm. The experimental setup and procedure Is described in
detail with particular emphasis on validation of assumptions
required for the analytical approaches used in calculating the modal
data.

The energy flow and the acoustic radiation of fluid-loaded
panels are investigated using the Energy Accountancy
Concept. The various energy components of the systems are
defined and studied. Each component is a function of the
excitation, the structure, the medium and their coupling.
An energy balance equation is written for the system. This
method is applied to study the acoustic radiation from a
point-excited clamped plate placed on the free surface of a
water tank. The radiation efficiency of the plate is
measured and compared to previous works. The energy
balance equation gives very good results at frequencies
between 50 Hz and 12 kHz. An undefined source of energy
dissipation is observed in one experiment. The results of
this study have shown that the Energy Accountancy Concept
can be used to describe the energy flow in a vibrating
structure under water-loading.