Abstract: A structural element made of a high impact sheet material, a resilient, semi-flexible core material, and a plurality of independent, preformed parallely-spaced rib members extending substantially across the width of said sheet material and fixedly attached thereto by an adhesive with said sheet material being flat, said plurality of rib members having adjacent, confronting side surfaces substantially parallel to one another, the forces created by bending of the structural element producing fractional detachment between at least some of said rib members and said sheet material being controlled by the width and height of said rib members and the distance between adjacent rib members and thereby determining the limit of bending of said structural element, thereby enabling a smooth surface of said high impact sheet material by preventing ripples and ridge lines therein with the bending of said structural element.

Abstract: A structural element for initial, substantially flat attachment to the surfaces of high impact sheet materials, and adapted for attachment to curved surfaces, includes: a first resilient, semi-flexible, sheet material having a given length and width; a second, flexible sheet material of substantially the same width as the first sheet material; a plurality of parallely-spaced, independent preformed rib members sandwiched between the first and second sheet material and each rib member extending substantially across the width of the first and second sheet material and fixedly attached to both the first and second sheet material by an adhesive with the first and second sheet material being flat, the width and height of the preformed rib members and the distance between adjacent rib members determining the limit of bending of the first or second sheet material; and at least one of the first and second sheet material being shearable, thereby enabling areas and the degree of bending within the areas of the first and