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Licensed Unlicensed Requires Authentication Published by De Gruyter June 11, 2013

The compressive response of carbon fiber composite pyramidal truss sandwich cores

K. Finnegan , G. Kooistra , H. N. G. Wadley and V. S. Deshpande

Abstract

Pyramidal truss sandwich cores with relative densities in the range 1 – 10 % have been made from carbon fiber reinforced polymer laminates using a snap-fitting method. The measured quasi-static uniaxial compressive strength increased with increasing from 1 to 11 MPa over the relative density range investigated here. A robust face-sheet/truss joint design was developed to suppress truss – face sheet node fracture. Core failure then occurred by either (i) Euler buckling () or (ii) delamination failure () of the struts. Micro-buckling failure of the struts was not observed in the experiments reported here. Analytical models for the collapse of the composite cores by Euler bucking, delamination failure and micro-buckling of the struts have been developed. Good agreement between the measurements and predictions based on the Euler buckling and delamination failure of the struts is obtained. The micro-buckling analysis indicates this mechanism of failure is not activated until delamination is suppressed. The measurements and predictions reported here indicate that composite cellular materials with a pyramidal micro-structure reside in a gap in the strength versus density material property space, providing new opportunities for lightweight, high strength structural design.


* Correspondence address, H. N. G. Wadley Department of Materials Science and Engineering 395 McCormick Road Wilsdorf Hall, P.O. Box 400745 Charlottesville, VVA 22904 Tel.: +1 434/982 5671 Fax: +1 434/9825677 E-mail:

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Published Online: 2013-06-11
Published in Print: 2007-12-01

© 2007, Carl Hanser Verlag, München

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