Method of manufacturing expanded reinforcing sheet material

A method of reinforcing an article having a substantially smooth surface, the method comprising,

• initially forming a laminated sheet structure by bonding a layer of a foamable adhesive material between two sheets of structural material,
• forming a series of laterally spaced lines of slits through said laminated sheet structure with the slits in each line being spaced from one another and being offset longitudinally with respect to the slits in adjacent lines of slits to form a plurality of elongated strands interconnected at their ends by integrally formed joints,
• simultaneously expanding the two structural sheets and the layer of foamable adhesive material of said laminated sheet structure by spreading said slits to form a pattern of generally diamond-shaped openings each defined by a plurality of the elongated strands and joints, each strand and joint including a segment of each of said two sheets of structural material disposed in spaced relation and having opposed, substantially parallel generally flat surfaces joined by said foamable adhesive with the joined surfaces being disposed at an acute angle to the plane of the expanded laminate structure,
• positioning the expanded laminated structure in contact with the substantially smooth surface of the article to be reinforced, and
• maintaining the expanded laminated structure in contact with the smooth surface while activating the foamable adhesive material to enlarge its volume sufficiently to extrude a portion of the foamable material from between the opposed surfaces of the joints and strands to form a bond between the expanded laminated structure and the substantially smooth surface.