ASA 129th Meeting - Washington, DC - 1995 May 30 .. Jun 06
5pSA6. Energy partitioning in a truss structure.
Kai-Ulrich Machens
Ira Dyer
Dept. of Ocean Eng., MIT, Cambridge, MA 02139
MIT is investigating both theoretically and experimentally wave
propagation in truss structures. Experiments were conducted to measure energy
partitioning in flexural, longitudinal, and torsional vibrations of specific
truss members. The truss consists of 109 aluminum struts assembled via 35
joints to form a regular structure of 11 cells connected in series. A complete
numerical analysis [Y. P. Guo, 3291(A) (1994)] finds that energy
equilibria among different wave types can be expected, the ratios of which are
dependent upon the distinct classes of struts making up the truss. This was
tested by simultaneous measurement of the transfer functions at various
locations along the axis of each strut considered. The truss was excited by
broadband white noise (5-kHz baseband) at one end of the truss. Wave number
processing extracts two complex wave amplitudes, each associated with traveling
waves propagating in opposite directions. Thus the spectral energy content of
the strut is known and is compared to others in the same class. In addition,
struts of other classes are measured to discuss issues related to equipartition
of energy, pass/stop bands and natural damping of complex branched structures.