Fatigue life enhancement of dovetail connector slots and noncircular openings

摘要

A pair of openings (14) are drilled in a workpiece (12) at locations spaced inwardly from an edge (76) of the workpiece (12). Each opening is cold-expanded by the passage of a mandrel (46') only, or a mandrel (46) and split sleeve (58), to create an annular zone of residual compressive stresses (72) in the workpiece material immediately surrounding the openings (14'). Then the workpiece (12) is cut along lines extending from the edge (76) inwardly to central regions of the cold-expanded openings (14'). The workpiece material between the two openings (14') and the two cuts (74) is removed. The edge portions (72) of the material in the vicinity of the cuts (74) and the openings (14') are machined to a final desired size and shape, to define connector slots (84) having cold- expanded round regions bounding the slots (84).