Torque transmitting shaft

A torque transmitting shaft comprising:

• a first member extending along an axis, the first member having an inner surface extending between a first end and a second end, the inner surface defining a plurality of first engagement elements disposed proximate the first end;
• and
• a second member extending along the axis and received within the first member, the second member having a first end portion, a second end portion, and an intermediate portion extending between the first end portion and the second end portion, the first end portion having a first spline portion, each member of the first spline portion is received within corresponding engagement elements of the plurality of first engagement elements;
• an engagement part disposed between the first plurality of engagement elements and the first spline portion;
• a first torsional stiffness rate is provided by the second member while a first torque is applied to the second member and while there is a tangential clearance between the first spline portion and the plurality of first engagement elements;
• a second torsional stiffness rate is provided by at least one of the first member and the second member while a second torque is applied to the second member and while there is no tangential clearance between the member of the first spline portion and an engagement element of the plurality of first engagement elements, whereat the member of the first spline portion is engaged with engagement elements of the plurality of first engagement elements, and
• a third torsional stiffness rate is provided by at least one of the first member and the second member while a third torque is applied to the second member, whereat the engagement part is partially compressed, whereat the tangential clearance remains between the member of the first spline portion and the engagement element of the plurality of first engagement elements.