### ASA 129th Meeting - Washington, DC - 1995 May 30 .. Jun 06

## 3aSA2. Measurement of the flexural wave power transmission and reflection
coefficients of joints using wave-number domain methods.

**Robert J. Unglenieks
**

**
Robert J. Bernhard
**

**
**
*School of Mech. Eng., Purdue Univ., 1077 Ray W. Herrick Lab., West
Lafayette, IN 47907-1077
*

*
*
Recently, a number of investigators have proposed so-called energy flow
analysis techniques to allow engineers to perform high-frequency structural
vibration studies of coupled structural elements. One key parameter required
for this analysis is the power transmission and reflection coefficients of the
joints that couple structural elements. A wave-number domain technique has been
developed which uses a spatial fast Fourier transform to transform velocity
data obtained in the spatial/frequency domain into the wave-number/frequency
domain. The resulting wave-number domain spectrum allows estimation of energy
flow segregated into right and left traveling components. Using the segregated
energy flows for all of the structural elements coupled at a joint, it is
possible to estimate the power transmission and reflection coefficients of the
joint. A ladder frame structural system is analyzed to determine the flexural
wave power transmission and reflection coefficients of ell- and tee-joints that
comprise the structure. The structure is forced so that only flexural and
longitudinal waves are excited. A scanning laser Doppler vibrometer is used to
collect the flexural wave velocity data. The estimates of the joint
coefficients are presented and compared to the analytical values for rigid
joints.