Stress redistribution system for threaded connection of a gas turbine engine spool

A system for a threaded connection, the system comprising:

• a shaft configured to rotate about an axis, the shaft configured as a hollow cylinder with an inner surface and a wall defined around the inner surface, the wall defining a section of the shaft as a tube-like structure;
• and
• a threaded fastener threadedly engaged with the shaft at a threaded connection, the threaded fastener applying a compressive load placing the shaft under a tensile load, the threaded connection extending from a loaded end adjacent a loaded interface where the compressive load is applied, to an unloaded end opposite the loaded end,
• wherein the threaded connection is defined along the axis by the nut and threads on the shaft,
• wherein the inner surface is configured with a contour so that the wall has a first thickness at the loaded end and a second thickness at the unloaded end that is different than the first thickness,
• wherein the contour forms a void along an axial length of the threaded connection and on an opposite side of the wall from the threaded connection, wherein the void is disposed axially solely within the threaded connection, wherein the wall has a varying thickness that extends from the loaded end to the unloaded end where the wall is thinner than a standard thickness of the wall outside the contour,
• wherein the wall is configured with more compliance at the loaded end as compared to at the unloaded end to reduce a stress resulting from the load at the loaded end and to redistribute the stress throughout threads of the threaded connection.

A system for a threaded connection, the system comprising:

• a shaft configured to rotate about an axis, the shaft configured as a hollow cylinder with an inner surface within the hollow cylinder and the shaft having a wall defined around the inner surface;
• and
• a fastener configured for threaded engagement onto the shaft at a threaded connection between the fastener and the shaft, the fastener configured to apply a compressive load holding the shaft under a tensile load, the threaded connection extending from a loaded end in line with a place of application of the compressive load, to an unloaded end opposite the loaded end,
• wherein the threaded connection is defined along the axis by the nut and threads on the shaft,
• wherein the inner surface is configured with a contoured cavity so that the wall has a first thickness at the loaded end and a second thickness at the unloaded end,
• wherein the first thickness is less than the second thickness so that the wall is configured with more compliance at the loaded end as compared to at the unloaded end to reduce a stress resulting from the load at the loaded end and to redistribute the stress to threads throughout the threaded connection,
• wherein the contoured cavity forms a void along an axial length of the threaded connection and on an opposite side of the wall from the threaded connection, wherein the void is disposed axially solely within the threaded connection.