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In-plane dynamic crushing of regular hexagonal honeycombs made of a material with elastic-linear strain hardening property. (A) Schematic of the finite element model. (B) Normalized plastic energy dissipation versus the crushing strain for two different normalized velocities
This and the next image are from:
D. Mousanezhad (1), R. Ghosh (1), A. Ajdari (2), A.M.S. Hamouda (3), H. Nayeb-Hashemi (1) and A. Vaziri (1)
(1) Department of Mechanical and Industrial Engineering, Northeastern University, Boston, MA, USA
(2) Department of Mechanical Engineering, Northwestern University, Evanston, IL, USA
(3) Mechanical and Industrial Engineering Department, Qatar University, Doha, Qatar
“Impact resistance and energy absorption of regular and functionally graded hexagonal honeycombs with cell wall material strain hardening”, International Journal of Mechanical Sciences, Vol. 89, pp 413-422, December 2014, https://doi.org/10.1016/j.ijmecsci.2014.10.012
ABSTRACT: This paper highlights the effects of cell wall material strain hardening and density functional gradation (FG) on in-plane constant-velocity dynamic crushing response and impact behavior of hexagonal honeycombs. Results show that cell wall material strain hardening influences the distinct deformation modes induced by crushing velocity generally observed in regular hexagonal honeycombs. This is seen by a delay in the onset of localized deformation up until intermediate crushing velocities after which localization becomes dominant smearing out differences brought about by cell wall material strain hardening (plasticity convergence). In addition, during the impact loading on regular honeycombs, it was found that increasing the cell wall material strain hardening decreases the rate of gain of maximum crushing strain with increments in initial kinetic energy of impact. On the other hand, introducing FG brings about new deformation patterns due to changes in material distribution and preferential cell wall collapse of the weaker members. Interestingly, although the dynamic localization effect at higher crushing velocities observed earlier was not found to be particularly affected by FG, gradient convergence (i.e. smearing out the effects of FG due to higher velocities analogous to plasticity convergence) was not observed. On the contrary, gradient convergence emerged at higher impacting velocities primarily brought about by a combination of initial deformation localization and its subsequent advancement into FG region ahead. The kinetic energy threshold for the emergence of this gradient convergence effect was found to be considerably delayed by cell wall material strain hardening.
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