Citation

Henderson B, Whitty JPM, Myler P, Chirwa C. Int. J. Crashworthiness 2007; 12(6): 689-698.

Copyright

(Copyright © 2007, Informa - Taylor and Francis Group)

DOI

10.1080/13588260701789425

PMID

unavailable

Abstract

The finite element method has been used to investigate the crashworthiness of regular conventional and re-entrant cellular foams in pristine and defect forms. Defects were introduced by randomly deleting vertical ribs (cell walls), diagonal ribs and vertical-plus-diagonal ribs from the honeycomb models, which with suitable boundary conditions approximated to three-dimensional foams. Generally, the calculations show that deleting ribs leads to a reduction in magnitude of the Young's moduli and Poisson's ratios, although there are some notable exceptions. In particular, the Young's modulus and Poisson's ratio along the x-axis (perpendicular to the vertical ribs) actually increase in magnitude slightly when vertical ribs are deleted. In the case of the re-entrant honeycomb, a transition from auxetic (negative Poisson's ratio) to non-auxetic (positive Poisson's ratio) behaviour occurs at a critical threshold for diagonal rib deletion. For the conventional honeycomb, the Poisson's ratio for loading in the y-direction remains approximately constant when diagonal ribs are deleted.