FINITE ELEMENT PREDICTIONS OF VIBRATION DAMPING INHONEYCOMB SANDWICH PANELS

摘要

The knowledge of the overall damping level and itssources in satellite structures and the suitable method tomodel it constitute a necessary step for reliable dynamicpredictions. As a first step of a damping characterization,the damping of honeycomb structural panels, which hasbeen identified as a main contributor to global damping,has been considered.This work presents the results of a collaboration betweenALCATEL SPACE and the Department of MechanicalEngineering of Bristol University. The inherent vibrationdamping mechanism in shear-stiff sandwich panels,including those with both aluminum and CFRP skins, isfirstly considered on a theoretical point of view thatreflects Bristol University damping experience. It is shownhow one may predict the theoretical modal properties ofthe sandwich panel from the stiffness and dampingproperties of its constituent components using basiclaminate theory, a first order shear deformation theory anda simple discretization method. A finite elementtranscription of this approach is also presented. It is shownto what extent this method can be implemented usingMSC/NASTRAN software functionality to predict theoverall damping value of a sandwich honeycomb panel foreach specific mode.In a second part, the MSC/NASTRAN predicted modalcharacteristics (frequency and damping) are comparedwith the experimentally obtained values for two specimensof typical aluminum core honeycomb panels (aluminumand CFRP skins) used by ALCATEL SPACE as structuralpanels. It has been shown through these results that themethod (theoretical and finite element) is satisfactory andpromising.