$E_1^{*}$	Young’s modulus of honeycomb panel in X1 direction, N/mm2
$E_2^{*}$	Young’s modulus of honeycomb panel in X2 direction, N/mm2
E S	Young’s modulus of honeycomb cell wall material, N/mm2
E*	Young’s modulus of regular hexagonal honeycomb panel, N/mm2
E tan	tangent modulus of honeycomb cell wall material, N/mm2
t	cell wall thickness, mm
l	length of single cell wall, mm
h	length of double cell wall, mm
b	honeycomb panel thickness, mm
θ	internal angle of the cell walls, degree
${\nu }_{12}^{*}$	Poisson’s ratio of honeycomb panel in X1 direction
${\nu }_{21}^{*}$	Poisson’s ratio of honeycomb panel in X2 direction
ν*	Poisson’s ratio of regular hexagonal honeycomb panel
ν	Poisson’s ratio of honeycomb cell wall material
$G_{12}^{*}$	Shear modulus of honeycomb panel in X1–X2 plane, N/mm2
${({\sigma }_{pl}^{*})}_1$	plateau stress of honeycomb panel in X1 direction, N/mm2
${({\sigma }_{pl}^{*})}_2$	plateau stress of honeycomb panel in X2 direction, N/mm2
${\sigma }_{pl}^{*}$	plateau stress of regular hexagonal honeycomb panel, N/mm2
${\sigma }_{ys}^{*}$	yield strength of honeycomb cell wall material, N/mm2
${\sigma }_{\max }^{*}$	first maximum compressive strength of honeycomb panel, N/mm2
${\sigma }_{130}^{*}$	plateau end (1.3 times the plateau stress), N/mm2
EA	energy absorption of honeycomb panel, J
REAE	relative energy absorption efficiency, %
L 0	original length of honeycomb panel, mm
F	force (load), N
ε	strain
ε 50%	50% strain
ε ple	plateau end strain
e	reinforcement tube thickness, mm
ρ	density of honeycomb cell wall material, g/cm3
V	velocity of moving top rigid plate, mm/s
f	frictional coefficient