Shaft assembly

A shaft assembly, comprising:

• a hollow shaft with an axis of rotation;
• and
• a hub body which is connected to the hollow shaft in a force locking manner;
• wherein the hollow shaft, viewed in cross-section, includes a circumferentially closed wall with a plurality of circumferentially distributed support portions that are in abutting contact with the hub body, and with spring portions spaced from an inner circumferential face of the hub body;
• wherein inner surface regions of the spring portions lie on a smaller radius around the axis of rotation than inner surface regions of the support portions;
• and
• wherein the hollow shaft is configured so as to have a spring rate for which the following applies:
• k
• ⁢
• 3
• =
• F
• rad
• U
• 3
• ⁢
• 4
• <
• π
• *
• l
• 3
• ⁢
• 4
• *
• E
• *
• (
• 1
• -
• π
• *
• D
• 3
• ⁢
• a
• 2
• 2
• *
• A
• -
• μ
• )
• -
• 1
• wherein:
• k3 is the spring rate,
• Frad are effective radial forces between the shaft and the hub body in an assembled condition,
• U34 is an effective interference between a largest outside diameter of the shaft and a smallest inner diameter of the hub body in an unmounted condition,
• E is a modulus of elasticity of the shaft,
• l34 is a length of a mating surface between the shaft and the hub body,
• D3a is twice a maximum radius of the shaft in the unmounted condition,
• A is a cross-sectional area of the shaft, and
• μ is a transverse contraction coefficient of the shaft.