Parameter	Definition
t 1	Rib thickness
L 1	Rib length
t 2	The thickness of the upper and lower walls
L 2	The distance between the ribs and the center of the unit cell
t 3	The thickness of the side walls
L 3	The length of the upper and lower walls
L4	The length of the connecting surface between the side wall and the upper and lower walls
h	The distance from the center of the cell to the upper and lower sides and the distance from the wall
t	The wall thickness of the unit cell structure
L	The length of the side wall
θ	The angle between the side wall and the vertical line
${\epsilon }_x$	The deformation of the sandwich structure in the x direction when the sandwich structure is compressed
${\epsilon }_y$	The deformation of the sandwich structure in the y direction when the sandwich structure is compressed
$v_{xy}^{*}$	The Poisson’s ratio of the sandwich structure
As	The area occupied by the wall plate of the unit cell
Aɑ	The effective total area of the unit cell
$E_x^{*},E_y^{*}$	The equivalent Young’s modulus of the sandwich structure in the x and y directions
Ex	The Young’s modulus of the structure material of the unit cell
$G_{xy}^{*}$	The equivalent shear modulus of the sandwich structure
ρ	The relative density of the re-entrant NPR sandwich structure
wi	The sound power of incident sound waves
wt	The transmitted sound wave sound power
STL	The sound transmission loss
A	Overall length of tensile test piece
B	Width of ends of tensile test piece
C	Length of narrow portion of tensile test piece
D	Width of narrow portion of tensile test piece
E	Transition radius outside of tensile test piece
F	Transition radius inside of tensile test piece
t*	Tensile test piece thickness of tensile test piece