Size and Shape Optimization of a Two Wheeler Connecting Rod by Structural Analysis

Connecting rod is the intermediate link between the piston and the crank and is responsible to transmit the push and pull from the piston pin to crank pin, thus converting the reciprocating motion of the piston to rotary motion of the crank. Connecting rod in automotives should be lighter and lighter, should consume less fuel. In the case of four stroke engines, during compression and power strokes the connecting rod is subjected to compressive loads and during the last part of the exhaust and the beginning of the suction strokes, to tensile loads. Since the compressive forces are much higher than the tensile force, therefore the cross-section of the connecting rod is analyzed and optimized based on the compressive load. In this work two wheeler connecting rod is selected, solid edge software is used for the modelling and ANSYS software is used for the analysis to find the stresses developed in connecting rod under static loading with compression at pin end and constraints at the crank end and these stress values are used to perform shape optimization. Size optimization is performed by reducing the web thickness of the connecting rod to optimize the size and the further analysis is carried out to find stress distribution, based on that shape optimization is done by considering shape finder as a design variable, maximum stress as a constraint and mass reduction as an objective of the connecting rod.