18-10-2012, 05:18 PM
Design and manufacture of an automotive hybrid aluminum
Design and manufacture of an automotive.pdf (Size: 1.35 MB / Downloads: 67)
Introduction
An automotive drive shaft transmits power from the
engine to the differential gear of a rear wheel drive vehicle
as shown in Fig. 1 [1]. The torque capability of the
drive shaft for passenger cars should be larger than 3500
Nm and the fundamental bending natural frequency
should be higher than 9200 rpm to avoid whirling vibration
[2]. Since the fundamental bending natural frequency
of a one-piece drive shafts made of steel or
aluminum is normally lower than 5700 rpm when the
length of the drive shaft is around 1.5 m [2], the steel
drive shaft is usually manufactured in two pieces to
increase the fundamental bending natural frequency
because the bending natural frequency of a shaft is inversely
proportional to the square of beam length and
proportional to the square root of specific modulus.
Design of the aluminum/composite drive shaft
The aluminum/composite drive shaft should satisfy
three design specifications such as static torque capability,
buckling torque capability and bending natural
frequency. The major role of the aluminum tube is to
sustain an applied torque while the role of the carbon
fiber epoxy composite is to increase bending natural
frequency. The carbon fiber epoxy prepreg was USN150
manufactured by SK Chemicals (Korea), whose properties
are similar to T300/5208. Tables 1 and 2 show the
mechanical properties of the carbon fiber epoxy composite
and the aluminum tube (6061-T6), respectively.
Conclusion
In this paper, a one-piece hybrid aluminum/composite
drive shaft for a rear wheel drive automobile was
developed with a new manufacturing method. The
composite materials were stacked on the inner surface of
the aluminum tube and co-cured to prevent the hybrid
shaft from being damaged by external impact and
moisture. The optimal stacking sequence for the composite
stacked on the inner surface of the aluminum tube
was determined considering the thermal residual stress
induced during co-curing operation. A press fit joining
method between the steel yoke with protrusions on its
surface and the aluminum tube was developed to increase
the reliability of joining and to reduce manufacturing
cost. The mass of the manufactured hybrid
aluminum/composite drive shaft was 3.3 kg, which was
only 25% of the conventional steel drive shaft. The static
torque capability and the fundamental natural frequency
were 4320 Nm and 9390 rpm, which exceeded
the design requirements.