3d printing-based 3d re-entrant negative poisson's ratio prefabricated composite protective structure and preparation method thereof

A three-dimensional (3D) printing-based 3D re-entrant negative Poisson's ratio prefabricated composite protective structure, comprising:

• multiple 3D double-branch re-entrant hexagonal unit cells, steel screws, and a lightweight foam material;
• wherein each of the multiple 3D double-branch re-entrant hexagonal unit cells is formed by rotating one of two double-branch re-entrant hexagonal units 90 degrees along a long axis direction thereof and then arranging the double-branch re-entrant hexagonal units orthogonally;
• wherein basic geometric parameters of the 3D double-branch re-entrant hexagonal unit cell comprise:
• a horizontal side length h, a unit outer cell wall length l1, a unit inner cell wall length l2, an angle θ1 between an outer inclined wall of the 3D double-branch re-entrant hexagonal unit cell and a vertical line, an angle θ2 between an inner inclined wall of the 3D double-branch re-entrant hexagonal unit cell and the vertical line, a wall thickness t of the 3D double-branch re-entrant hexagonal unit cell, a height y of the 3D double-branch re-entrant hexagonal unit cell, and a length x of the 3D double-branch re-entrant hexagonal unit cell;
• wherein the height y of the 3D double-branch re-entrant hexagonal unit cell, and the length x of the 3D double-branch re-entrant hexagonal unit cell are calculated according to the following formulas:
• x
• =
• 2
• ⁢
• (
• h
• -
• l
• 2
• -
• sin
• ⁢
• θ
• 2
• )
• y
• =
• 2
• ⁢
• l
• 1
• -
• cos
• ⁢
• θ
• 1
• ;
• and
• wherein holes are defined at middle positions of vertical side branch inclined ribs of the 3D double-branch re-entrant hexagonal unit cell, the holes are configured for the steel screws to pass therethrough to fix the 3D double-branch re-entrant hexagonal unit cell with the other 3D double-branch re-entrant hexagonal unit cells adjacent to the 3D double-branch re-entrant hexagonal unit cell, and the lightweight foam material is uniformly dispersed within the multiple 3D double-branch re-entrant hexagonal unit cells.