chamfer 23 immediately below the coolest portion of the hub 21 thereby forcing the axial stress to be the greatest at an off center position thereby decreasing its magnitude this is shown in fig3 where the area of greatest stress indicated at u201c x u201d is shifted to a forwardly off center position optimum shape angle size and dimensions of the chamfer are determined empirically by implementing a design change and then reviewing the effect of the change through computer analysis to observe the resulting stresses rather than by a purely analytical method the design process is adapted to balance the decrease in axial stress with an accompanying increase in hoop stress caused by lowering the cross sectional area of the disk hub 21 in a preferred version the chamfer 23 intersects the non chamfered portion of the hub surface 22 at the same axial location as the center of maximum axial tensile stress the chamfer 23 is preferably planar as shown with radiused fore and aft transitions and may be between about 0 and 50 degrees prior art disk hubs in a specific general electric gas turbine engine were rated at 11 000 cold start cycles incorporation of the chamfer as shown and described above into a computer.