The advanced composite materials such as graphite, Kevlar, glass and carbon with suitable resins are widely used because of their high specific strength and high specific modulus for long, power drive shaft applications (for example: propeller shaft) advanced composite materials are ideally suited.
And their elastic properties can be tailored to increase the torque they can carry as well as the rotational speed at which they operate. The propeller shafts are used in automotive, air craft and marine drive applications.
The automotive industry is exploiting composite material technology for structural component construction in order to obtain the reduction of weight without decrease in vehicle quality and reliability.
It is known that energy conservation is one of the most important objective in vehicle design and reduction of weight is one of the most effective measure to obtain this result.
In fact, there is almost a direct proportionality between the weight of a vehicle and its fuel consumption, particularly in heavy traffic areas like city driving.
Purpose of the Propeller Shaft The torque that is produced from the engine and transmission must be transferred to the rear wheels to push the vehicle forwardand reverse. The propeller shaft must provide a smooth, uninterrupted flow of power to the axles. The propeller shaft and differential are used to transfer this torque
Functions of the Propeller Shaft
1) First, it must transmit torque from the transmission to the differential gearbox.
2) During the operation, it is necessary to transmit maximum low-gear torque developed by the engine.
3) The propeller shafts must also be capable of rotating at the very fast speeds required by the vehicle.
4) The propeller shaft must also operate through constantly changing angles between the transmission, the differential and the axles. As the rear wheels roll over bumps in the road, the differential and axles move up and down. This movement changes the angle between the transmission and the differential.
5) The length of the propeller shaft must also be capable of changing while transmitting torque. Length changes are caused by axle movement due to torque reaction, road deflections, braking loads and so on. A slip joint is used to compensate for this motion. The slip joint is usually made of an internal and external spline. It is located on the front end of the propeller shaft and is connected to the transmission
The following conclusions are drawn from the present work:
1) The kevlar and High Modulus Carbon/epoxy composite propeller shafts have been designed to replace the conventional steel propeller shaft of an automobile.
2) A composite propeller shaft for rear wheel drive automobile has been designed by using kevlar and High Modulus Carbon/Epoxy composites with the objective of minimization of weight of the shaft which was subjected to the constraints such as torque transmission, torsional buckling capacities and natural bending frequency.
3) The deflection in the Hm carbon propeller shaft is approximately 2.5 times reduced than the conventional steel propeller shaft.
4) The Fundamental natural frequency of the Hm carbon/epoxy propeller shaft is reduced when compared to the conventional steel propeller shaft
5) The torsional buckling capacity of the propeller shaft increased 3 times when its made by Hm carbon material instead of conventional steel material.
6) Natural frequency using Bernoulli-Euler and Timoshenko beam theories was compared. The frequency calculated by using the Bernoulli Euler beam theory is high, because it neglects the effect of rotary inertia & transverse shear of the shaft.
7) The weight savings of the kevlar and High Modulus Carbon/Epoxy shafts were equal to 76.08 % and 78.29 % of the weight of steel shaft respectively