Sandwich construction element with an open core structure composed of close packed tetrahedra

A sandwich construction element, comprising:

• a first element with a face, extending in a longitudinal direction with a thickness and a height being smaller than the longitudinal length;
• a second element with a face, extending in the same longitudinal direction as the first element with a thickness and a height being smaller than the longitudinal length, wherein the second element is facing the face of the first element;
• and
• an open core structure arranged between, and operatively connected to the first element and the second element, wherein the open core structure comprises a plurality of close packed tetrahedron structures, wherein the tetrahedron structures are asymmetric and are arranged to form one or more unit cells defining a box shaped volume, the box shaped volume having perpendicular sides;
• wherein the open core structure comprises at least two flat elements arranged between the first element and the second element, wherein the at least two flat elements are arranged between the faces of the first element and the second element, and facing each other with a first distance between the two elements;
• wherein the one or more unit cells are arranged between two of the at least two flat elements;
• wherein each unit cell comprises two parallelograms arranged in an overlapping intersecting relation along a diagonal of the two parallelograms, with an angle between the two parallelograms;
• wherein each of the parallelograms comprises a slit along the diagonal of the parallelogram extending inwardly from a corner of the parallelogram to at least the center of the parallelogram;
• and
• wherein the slit receives a corresponding parallelogram with a slit such that the two parallelograms are joined along the diagonal of each parallelogram.