Optimal design of the press fit joint for a hybrid aluminum/composite drive shaft

In this work, a one-piece hybrid drive shaft composed of aluminum and carbon/epoxy composite was designed for a rear wheel drive automobile. The aluminum yoke was joined to the hybrid shaft by the press fit joining method using a steel ring which has many small teeth to increase reliability and to reduce manufacturing cost. To obtain high strength of the press fit joint, an optimal design method for the teeth was devised with respect to number and shape of the steel teeth. The developed optimal design method predicted well the static torque capability and failure mode of the press fit joint. Then, the prototype one-piece automotive hybrid aluminum/composite drive shaft was manufactured and tested. The one-piece automotive hybrid aluminum/composite drive shaft allowed 50% mass reduction compared with the conventional two-piece steel drive shaft.