02-08-2013, 02:51 PM
GENETIC ALGORITHM BASED OPTIMUM DESIGN OF COMPOSITE DRIVE SHAFT
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ABSTRACT
In this work, an attempt has been made to optimize design parameters of a composite drive
shaft, which replaces a conventional steel shaft in an automobile power-train, using Genetic
Algorithm (GA). The parameters such as ply thickness, number of plies and stacking sequence
were optimized for E-Glass/Epoxy and Boron/Epoxy shafts using GA with the objective of
weight minimization of the composite shaft which is subjected to constraints such as torque
transmission, torsional buckling load and fundamental natural frequency. The weight reduction
can be achieved considerably. The stresses distributed along shaft thickness were analyzed and
found to be within allowable limits.
INTRODUCTION
Substituting composite structures for conventional metallic structures has many advantages
because of higher specific stiffness and strength of composite materials. Advanced composite
materials seem ideally suited for long, power drive shaft applications. Their elastic properties
can be tailored to increase the torque and the rotational speed at which they operate. The
advanced composite materials such as Boron, Graphite, Carbon, Kevlar and Glass with suitable
resins are widely used because of their high specific strength (strength/density) and high
specific modulus (modulus/density)1. Polymer matrix composites were proposed for light
weight shafts in drivelines for automotive3, 4 industries. A GA based on natural genetics has
been used for this work5. The fairly new GA was and applied for the design optimization of
steel and composite leaf springs in the previous study by authors6, 7. Most of the automobiles
employs shafts in drive-trains and weight reduction of drive shaft by optimization of design
parameters is highly desirable if it can be achieved without cost increase and loss of quality and
reliability.
DESIGN OBJECTIVES
The torque transmission capability of the drive shaft for passenger cars, small trucks, and vans
should be larger than 3,500 Nm and fundamental natural bending frequency of the shaft should
be higher than 6,500 rpm to avoid whirling vibration. The outer diameter (do) restricted to100
mm due to space limitations and here it is taken as 90 mm. The drive shaft was designed
optimally to the specified design requirements5.
CONCLUDING REMARKS
A procedure to design a composite drive shaft is suggested.
Drive shaft made up of E-Glass/ Epoxy and Boron/Epoxy multilayered composites have
been designed.
The designed drive shafts are optimized using GA for better stacking sequence, better
torque
transmission capacity and bending vibration characteristics.
The usage of composite materials and optimization techniques has resulted in
considerable
amount of weight saving in the range of 48% to 86% when compared to steel shaft.
These results are encouraging and suggest that GA can be used effectively and
efficiently in
other complex and realistic designs often encountered in engineering applications.
The stresses and strains along the thickness of the shaft are found to be within allowable
limit.