STRESSES IN A SPLINELESS DRIVE FOR AERO-ENGINES

This paper describes an alternative to splines for connecting turbine discs to shafts. The trilobe shape consists of six smoothly blending 6 0 degrees circular arcs of two alternating radii; it is between a circ le (both radii equal) and a triangle (smaller radius zero, larger radi us infinite). Frozen-stress, photoelastic models of a realistic disc a nd a tubular shaft have been designed, made and loaded centrifugally, under static torsion and under combined torsion and rotation. The resu lts show that the greatest centrifugal stresses in the disc occur in t he bore at the tips of the trilobe and the greatest contact stresses o ccur near the transition from the larger to the smaller radius. The ce ntrifugal stress concentrations due to the trilobe were small. Bore de formation and backlash due to differential centrifugal expansion were measured and found to be acceptable for a similar ceramic or nickel al loy disc.