An impact resistant structure is described which comprises a substantially sinusoidally shaped elastically collapsible open-celled fluted layer disposed between but not bonded to constraining layers, whereby in an impact event, the flutes are free to move between the constraining layers and stress concentrations in the collapsing flutes immediately beneath the impacting object are minimized by the absorption of impact forces by neighboring flutes that resiliently collapse in an accordion-like fashion, and return substantially to the original shape after impact without permanent damage to the structure.
The present application claims the benefit of the filing date of Provision Application Ser. No. 06/122,699 filed Mar. 3, 1999, the entire contents of which Provisional Application are incorporated by reference herein.
A print medium that is expandable and collapsible comprises two sheets separated by at least one collapsible brace. The collapsible brace includes a first wall attached to one of the sheets and a second wall that swings in relation to the first wall. The swinging motion of the second wall in one direction expands a distance between the two sheets, while a swinging motion of the second wall in the opposite direction collapses the distance between the two sheets. At least one sheet of the paper may include an ink receiving layer. When the collapsible brace is expanded, the print medium becomes a substantially rigid structure.
