14-11-2012, 01:15 PM
Composite Driveshaft
composite shaft 2.pdf (Size: 1.93 MB / Downloads: 138)
Introduction
A driveshaft is the connection between the transmission and the rear axle of the
car. As shown in Figure 1, power generated by the engine is transferred to the
transmission via a clutch assembly. The transmission is linked to the driveshaft by a
yoke and universal joint, or u-joint, assembly. The driveshaft transmits the power to the
rear end through another yoke and u-joint assembly. The power is then transferred by the
rig and pinion or rear differential to the rear wheels.
Purpose
To reduce to the amount of rotating mass in the drive train of a locally owned
1968 Mustang, a light weight driveshaft will be constructed. In racing, every hundredthof-
a-second counts. The race car, pitted in an unending battle against the clock, is
modified to squeeze every bit of horsepower out of it. The drag car is full of racing
equipment, but currently has a steel driveshaft. The new drive shaft should take less
energy to spin therefore more of the energy produced by the engine can be transferred to
the wheels.
In addition to increasing the efficiency, the composite shaft will be safer than a
steel driveshaft. When a steel shaft fails, it projects shrapnel in all directions. There is
also a possibility that the shaft may dig into the ground and catapult the vehicle into the
air. When a composite shaft fails, it breaks into small fiber fragments posing no danger.
Objectives
The objective of this study is to design a composite driveshaft, build it, and test
the performance of the car with the new driveshaft in place.
Design
A driveshaft is a hollow tube which transmits torque from the transmission to the
differential. The shaft has a yoke at each end which connects to the transmission and the
rear differential by the means of u-joints. A slip yoke, with internal gear teeth, slides into
the transmission and allows the shaft to travel in the axial direction of the shaft when the
rear axel moves up or down. This slip yoke allows transmittance of torque while
preventing the shaft from experiencing tensile or compressive loads. The u-joints allow
the transmittance of torque without applying bending stresses to the shaft.
Fabrication
There are several things to consider when picking a fabrication method. Time is a
major consideration. There is little time for fabrication, so the fabrication process has to
be quick. The fiber has to be laid at specific angles to give the shaft certain
characteristics. The weave patterns have to be tight and compact. Resin has to be
applied evenly. The shaft has to be wound in a way such that the yokes can be easily
attached. The easiest fabrication method for creating a hollow tube is filament winding.
Filament winding is an automated process in which a filamentary yarn in the form of tow
is wetted by resin and uniformly and regularly wound about a rotating mandrel. The
filament winder can be programmed to create specific and tightly wound patterns.
To create a composite part on the winder, a winding pattern is needed, along with a
mandrel, mold release, fiber, resin and hardener, a way to apply even pressure to the part and a
curing procedure.