Fatigue-resistance sheet slitting method and resulting sheet

A sheet of material formed for bending along a bend line comprising:

• a sheet of material having a plurality of bend-inducing structures configured and positioned to produce bending along the bend line, at least one bend-inducing structure having arcuate return portions extending from opposite ends of the bend-inducing structure;
• wherein the arcuate return portions return along the bend-inducing structure toward the other return portion;
• and
• wherein the arcuate return portions curve back toward the bend line at distal ends of the return portions.

A method of increasing the fatigue resistance of a structure formed by bending a sheet of material along a bend line having a plurality of bend-inducing structures, the method comprising:

• forming the sheet of material with the plurality of bend-inducing structures to produce bending of the sheet of material along the bend line;
• bending the sheet of material along the bend line to produce a three-dimensional bent structure;
• and
• during the forming step, forming at least one of the bend-inducing structures with opposite ends curving away from the bend line and arcuate return portions;
• wherein the arcuate return portions curve away from the opposite ends and back along the slit toward the other return portion;
• and
• wherein the return portions curve back toward the bend line at distal ends of the return portions.