Flexible multi-wall sheet

A multi-wall sheet made of a thermoplastic with a relatively high shear modulus, having a structure comprising:

• a first wall comprising a single generally flat sheet;
• a second wall comprising a single sheet generally parallel to, extending a length of, and separated from the first wall, having a transverse contour of a form incorporating a series of alternating flat and arced sections each with an apex toward the first wall and extending a length of the second wall;
• an intermediate single sheet between, generally parallel to, extending the length of the second wall, and separated from the first wall, having a transverse contour of a form similar to the second wall and having an apex of each arc generally aligned to an apex of each arc of the second wall and extending a length of the intermediate sheet;
• a plurality of ribs located between, perpendicular to, and connected to the first wall and the intermediate sheet and each rib equidistant between two adjacent arcs in the transverse contour of the intermediate sheet and extending the lengths of the first wall and intermediate sheet;
• and
• a plurality of ribs located between, perpendicular to, and connected to the second wall and the intermediate sheet and each rib equidistant between two adjacent arcs in the transverse contour of the second wall and extending the lengths of the intermediate sheet and second wall.

A multi-wall sheet made of a thermoplastic with a relatively high shear modulus, having a structure comprising:

• a first wall comprising a single generally flat sheet;
• a second wall comprising a single sheet generally parallel to, extending a length of, and separated from the first wall, having a transverse contour of a form incorporating a series of alternating flat and arced sections each with an apex toward the first wall and extending a length of the second wall;
• a plurality of intermediate single sheets between, generally parallel to, extending the lengths of, and separated from the first wall and second wall, each having a transverse contour of a form similar to the second wall and having an apex of each arc of each intermediate sheet generally aligned to an apex of each arc of the second wall and extending a length of the plurality of intermediate sheets;
• a plurality of ribs located between, perpendicular to, and connected to the first wall and an intermediate sheet adjacent the first wall and each rib equidistant between two adjacent arcs in the transverse contour of the intermediate sheet adjacent the first wall and extending the length of the first wall and intermediate sheets;
• a plurality of ribs located between, perpendicular to, and connected to adjacent intermediate sheets and each rib equidistant between two adjacent arcs in the transverse contour of each intermediate sheet and extending the length of the plurality of intermediate sheets;
• a plurality of ribs located between, perpendicular to, and connected to the second wall and an intermediate sheet adjacent the second wall and each rib equidistant between two adjacent arcs of the transverse contour of the second wall and extending the lengths of the second wall and plurality of intermediate sheets.