US Patent 7939158 Double walled structural reinforcement

A double walled reinforcement structure and method for making a double walled reinforcement structure having a plurality of longitudinally extending and nested structural members. Each structural member comprises a first cell having a first cross-section and a second cell having a second cross-section. The second cell is positioned within the first cell and the second cell contacts the first cell in a plurality of locations to provide mutual support of the cells in a manner increasing the tensile and compressive strength of the structure.