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Fatigue Analysis and Validation of Fracture Split Connecting Rod for Value Engineering Using 1D and 3D Simulation Tools

Technical Paper
2016-01-1735
ISSN 0148-7191
DOI: https://doi.org/10.4271/2016-01-1735
Published March 27, 2016 by SAE International in United States
Annotation of this paper is available
 
Sector:
Automotive  
Language: English

Abstract

To compete with the current market trends there is always a need to arrive at a cost effective and light weight designs, hence the need for upgrading the existing/proven integral connecting rod to fracture split connecting rod. This technique provides gains as weight reduction and consequently reducing noise and vibration due to the decrease of the oscillating mass from the system. Using the proposed fracture split connecting rod, it is estimated that cost savings of up to 10%, reduction in weight and better fatigue performance (25% - 30%) can be achieved. For this, we have used simulation tools to reduce number of physical tests and thereby achieving considerable reduction in design and development time and cost.
High carbon alloy steel used for manufacturing fracture split connecting rod and it doesn’t require additional heat treatment after hot forging. Fracture split connecting rod is made of single forged blank and later splitted into two parts (Cap & Shank) unlike conventional type of connecting rods, in which shank and cap are separately forged and machined. In fracture split connecting rod - the requirement of additional machining of mating surface is prevented, which means a substantial savings in machining cost. Besides, a firm contact between shank and cap improves stiffness and compatibility with other crank-train moving parts - a definite merit in engine performance [2].
The present study undertakes a FEA based approach for development of fracture split connecting rod. Also it is aimed to predict the fatigue life of the connecting rod under operating loads.
Tensile & Compressive loads coming on the connecting rod were calculated from 1D Software (AVL Excite). These loads were applied on the connecting rod in four load steps i.e. Interference, Assembly loads, tensile load & compressive load using 3D Software (Ansys). Then, the stress results from stress analysis were used as an Input to the fatigue solver (FEMFAT) for evaluating fatigue strength of connecting rod. And lastly, these results were experimentally validated.