MEASUREMENT OF BENDING WAVE REFLECTION AND IMPEDANCE IN A BEAM BY THE STRUCTURAL INTENSITY TECHNIQUE

For vibration energy propagating in one dimension, structural intensity methods can be extended to the determination of the mechanical and the reflection coefficient. Following a short survey of the respective measurement of acoustic impedance, frequency-domain expressions are derived for alternative ways of estimating the impedance and reflection coefficient for bending waves in a beam. In laboratory experiments the known method of measuring the reflection of sound waves in ducts was shown to be applicable to beams. The simplest suggested method for estimating the impedance, which is based on the assumed wave impedance and the estimated reflection coefficient, gave the most reliable results. © 1993 Academic Press Limited.