Involute splines in torque transmitting joints are prone tonon-uniform contact loading along their length especially inlightweight, relatively flexible applications such as a helicoptermain rotor shaft-to-rotor hub joint. The structural stiffness andinternal load paths of the two members in the joint affect splinetooth contact pressure distribution. In such applications, in theabsence of lead corrections, the torque is transferrednon-uniformly along the length of the spline resulting in aconcentration or peaking of the tooth contact load at one end ofthe spline.
A significantly improved tooth load distributionwas achieved forsplines for the Low Maintenance Rotor (LMR) version of the CH-47Chinook helicopter main rotor shaft-to-rotor hub joint by applying,to the internally splined member, complex lead corrections whichvaried continuously along the length of the spline. The requiredlead corrections were determined analytically using finite elementmethods (FEM). Rotor hub splines with the analytically determinedlead corrections were manufactured and tested under design loadconditions. A standard CH-47 rotor shaft-to-hub joint, which uses astep lead correction between splines, was previously tested. Straingages were used to infer contact load distribution along the lengthof the splines.
Test data indicated that the complex lead corrections resultedin a nearly uniform contact load distribution along the length ofthe spline at the design torque load. The data also showed that theload distribution for the splines with the complex lead correctionswas significantly improved relative to the contact loaddistribution of the baseline splines. This work was performed underthe U.S. Army Aviation and Missile Command (AMCOM) Low MaintenanceRotor (LMR) hub development contract DAAH01-99-3-R001.
- Edition:
- 04
- Published:
- 10/01/2004
- Number of Pages:
- 16
- File Size:
- 1 file , 1.5 MB
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