A paper summarizes a continuing program of vibro-acoustic testing of two aircraft fuselage structures: (1) a 12-ft (3.7-m)-long generic aluminum test-bed cylinder that contains stiffening rings and stringers and (2) the 40-ft (12.2-m)-long fuselage of a 10-passenger turboprop airplane, made of honeycomb core and graphite/epoxy face sheets. Each structure is mounted on compliant supports that permit approximately free vibration and is instrumented with more than 200 accelerometers, which are positioned according to predictions of the first 100 vibrational modes. Subsequent acoustic tests will focus on measurement of interior noise fields created by exterior mechanical and acoustic sources.

This work was done by Richard S. Pappa and Ralph D. Buehrle of Langley Research Center and Jocelyn I. Pritchard of the Vehicle Technology Directorate of the U. S. Army Research Laboratory. L-17851