Eurocopter Deutschland Gmbh

Ottmar Haider

Horst Bansemir

Markus Bauer

Albert Gietl

Christian Ritzer

Walter Gembler

A sandwich composite panel (,) provides a load bearing structural member as well as noise protection, especially for a helicopter fuselage cell or cabin. The panel (,) includes an inner honey-comb core (,) made up of hollow cell bodies (,) extending trans-versely and sandwiched between first and second cover skins (,) of fiber composite material. In order to achieve a low weight, a simple manufacturing, and good noise absorption, at least one of the cover skins (,) adapted to face the main source of noise (H) is made up of an open mesh fiber composite net (,) and a flexible cover film (,) applied on the outer surface of this fiber composite net (,). The net (,) has a smaller mesh size than the inner cross-sectional size of the hollow cell bodies (,).

Noise attenuating sandwich composite panel

A solar generator for use in satellites or spacecraft includes a plurality of solar cells mounted on a support structure panel. The support structure panel includes a honeycomb cell structure core (4) sandwiched between a bottom cover skin (5) and a top cover skin (2). Vibration damping elements (11) are incorporated and bonded into the honeycomb core, and vibration damping film strips (10) are adhesively bonded onto an outer surface of at least one of the outer cover skins. The damping elements (11) respectively include a damping ring (13) made of an elastomeric material, between inner and outer structural rings (14, 12), whereby the outer ring is bonded to the honeycomb core and the inner ring provides a mounting location. The damping film strips are positioned at locations of maximum vibrational excitation in the panel due to noise pressure loading. The damping elements damp vibrations in the range from 30 Hz to 100 Hz, and the damping film strips damp noise pressure loads in the frequency range from 150 Hz to 500 Hz.

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Unterhaching, Germany

Ottmar Haider