The driveshaft is the power transmission shaft between the transmission and the defferential gear box in the real wheel driving automotive. A two-piece steel driveshaft have three universal joint, a spline and a shaft support bearing. The steel driveshaft with the two short section have a sufficiently high first natural frequency to rule out the whirling vibrations by the resonance. The requirements of the driveshaft design must support a torque load in excess of 1300 Nm have the first natural frequency in the excess of 6500 rpm.
The one-piece composite/aluminum driveshaft have a cocured composite/aluminum shaft with two universal joint and a spline. High specific modulus of composite material make it possible that the one-piece driveshaft have high first natural frequency and high strength aluminum tube(255 MPa) support a torque load. The light composite/aluminum structure make the mass of one-piece driveshaft a half of that of the two-piece driveshaft and reduce the use of a universal joint and a shaft support bearing.
The one-piece composite/aluminum driveshaft have the first natural frequency of 9000 rpm (Data from FFT analyzer, Design value : 9730 rpm )and the maximum torque transmission capability of 2600 Nm.
Cocure method that joint composite and aluminum cause the residual thermal stress at the interface of the two material induced the wide difference of C.T.E. between composite and aluminum. The method for the minimization of the residual thermal stress at the interface is proposed that is to compress the aluminum tube before curing composite. The finite element method and the fatigue test of the smaller specimen verify the effect of that method.
Serration connect the one-piece composite/aluminum tube with the universal joints. Serration is preferable to welding in the case of using composite material vulnerable by heat.
The whirling tester is manufactured that is composed by motor, bearing units and frequency converter for the control of the rotating velocity. The whirling test is conducted that the one-piece composite/aluminum driveshaft safely rotate to 3500 rpm.
The fatigue tester is produced that is constituted by single acting cylinder, pneumatic control units, load cell and electrial circuit for the sequencial control. The fatigue test is performed that the one-piece composite/aluminum driveshaft safely drive to $10^7$ cycle in the condition of maximum torque 365 Nm ( Torque application frequency : 6 Hz )
