Sheet with alternate protrusions and recesses

A sheet of material having a plurality of bends forming a succession of alternate protrusions and recesses with spaces between successive protrusions on the one hand and successive recesses on the other, the walls of each such protrusion and recess containing non-rectangular elementary surfaces joining each other in an undulatory manner at the ridges of said protrusions and recesses along a single line having a plurality of points at which it changes direction to form a plurality of undulations and at each of which points border lines of at least four of said elementary surfaces converge, said surfaces being ruled in a direction extending from one ridge line to another, the sum of the angles formed on said surfaces between said border lines at each of said points being equal to 360.degree., said sheet being of such configuration that it (1) is completely developable on the plane to which it is expanded and (2) cannot be completely contracted so that each of its ruled elementary surfaces is in complete surface area contact with its next adjacent ruled elementary surface.

A sheet of material having a succession of alternate protrusions and recesses with spaces between successive protrusions on the one hand and successive recesses on the other, the walls of each such protrusion and recess being composed exclusively of non-rectangular elementary surfaces joining each other in an undulatory manner at the ridges of said protrusions and recesses along a single line having a plurality of undulations at each of which points border lines of at least four of said elementary surfaces converge, said surfaces being ruled in a direction extending from one ridge line to another, the sum of the angles formed on said surfaces between said border lines at each of said points being equal to 360.degree..

A sheet of material having a succession of alternate protrusions and recesses with spaces between successive protrusions on the one hand and successive recesses on the other, the walls of each such protrusion and recess containing non-rectangular elementary surfaces joining each other in an undulatory manner at the ridges of said protrusions and recesses along a single line having a plurality of points at which it changes direction to form a plurality of undulations and at each of which points border lines of at least four of said elementary surfaces converge, said surfaces being ruled in a direction extending from one ridge line to another, the sum of the angles formed on said surfaces between said border lines at each of said points being equal to 360.degree., said sheet being of such configuration that it (1) is completely developable on the plane to which it is expanded and (2) cannot be completely contracted so that each of its ruled elementary surfaces is in complete surface area contact with its next adjacent ruled elementary surface.

A sheet of bendable material having a succession of alternate protrusions and recesses with spaces between successive protrusions on the one hand and successive recesses on the other, the walls of each such protrusion and recess containing elementary surfaces joining each other in an undulatory manner at the ridges of said protrusions and recesses along a single line having a plurality of points at which it changes direction to form a plurality of undulations and at each of which points border lines of at least four of said elementary surfaces converge, said surfaces being ruled in a direction extending from one ridge line to another, the sum of the angles formed on said surfaces between said border lines at each of said points being equal to 360.degree., said sheet being of such configuration that it (1) is completely developable on the plane to which it is expanded and (2) cannot be completely contracted so that each of its ruled elementary surfaces is in complete surface area contact with its next adjacent ruled elementary surface.

A sheet of material having a succession of alternate protrusions and recesses with spaces between successive protrusions on the one hand and successive recesses on the other, the walls of each such protrusion and recess containing elementary surfaces joining each other in an undulatory manner at the ridges of said protrusions and recesses along a single line having a plurality of points at which it changes direction to form a plurality of undulations and at each of which points border lines of at least four of said elementary surfaces converge, said surfaces being ruled in a direction extending from one ridge line to another, the sum of the angles formed on said surfaces between said border lines at each of said points being equal to 360.degree., said sheet being of such configuration that it (1) is completely developable on the plane to which it is expanded and (2) is contractible from its planar form only to a point at which it is locked against further contraction notwithstanding the fact that less than all of the ruled elementary surfaces are in complete surface area contact with their next adjacent ruled elementary surfaces.

A sheet of material having a plurality of bends forming a succession of alternate protrusions and recesses with spaces between successive protrusions on the one hand and successive recesses on the other, the walls of each such protrusion and recess containing non-rectangular elementary surfaces joining each other in an undulatory manner at the ridges of said protrusions and recesses along a single line having a plurality of points at which it changes direction to form a plurality of undulations and at each of which points border lines of at least four of said elementary surfaces converge, said surfaces being ruled in a direction extending from one ridge line to another, the sum of the angles formed on said surfaces between said border lines at each of said points being equal to 360.degree., said sheet being of such configuration that it (1) is completely developable on the plane to which it is expanded and (2) is contractible from its planar form only to a point at which it is locked against further contraction notwithstanding the fact that less than all of the ruled elementary surfaces are in complete surface contact with their next adjacent ruled elementary surfaces.