A process for designing and manufacturing precision-folded, high strength, fatigue-resistant
structures and a sheet therefore. The techniques include methods for precision
bending of a sheet of material (41, 241, 341, 441, 541) along a bend line
(45, 245, 345, 445,543) and a sheet of material formed with bending strap-defining
structures, such as slits or grooves (43, 243, 343, 443, 542), are disclosed.
Methods include steps of designing and then separately forming longitudinally extending
slits or grooves (43, 243, 343, 443, 542) through the sheet of material
in axially spaced relation to produce precise bending of the sheet (41, 241,
341, 441, 541) when bent along the bend line (45, 245, 345, 445, 543).
The bending straps have a configuration and orientation which increases their strength
and fatigue resistance, and most preferably slits or arcs are used which causes
edges (257, 457) to be engaged and supported on faces (255, 455)
of the sheet material on opposite sides of the slits or arcs. The edge-to-face
contact produces bending along a virtual fulcrum position in superimposed relation
to the bend line (45, 245, 345, 445, 543). Several slit embodiments (43,
243, 343, 443, 542) suitable for producing edge-to-face engagement support
and precise bending are disclosed, as is the use of the slit sheets to produce
various three-dimensional structures and to enhance various design and fabrication techniques.