Connecting Rod

CONNECTING ROD

NILESH SINGH VIKASH KUMAR  YASHDEEP  Y ASHDEEP SARASW SARASWA AT

INTRODUCTION FUNCTIONS FORCE ANALYSIS SELECTION DESIGN

OF MATERIAL

PROCEDURE

manufacturing

INTRODUCTION The

connecting rod or conrod connects the piston to the crank or crankshaft, in a reciprocating piston engine. Converts

linear motion into rotating motion

FUNCTIONS 

Transmit either a push or a pull for  charge(fuel+air) inlet or exhaust Rotate

the crank through both halves of a revolution, i.e. piston pushing and piston pulling Transmits

reciprocating motion into

rotary Transfers

lubricant oil from crank pin to piston pin providing a splash of oil.

FORCE ANALYSIS GAS PRESSURE  Act

at the time of  expansion. Force

acting on piston gets transferred on small end of  connecting rod. Vital

for design of cross section & eye of connecting rod.

FORCE ANALYSIS INERTIA FORCES  Act

after the completion of  exhaust due to vacuum generation. Suction

takes place due to these forces. Vital

for design of big end cap & bolts.

Failure of connecting rod BUCKLING IT TAKES PLACE WHEN THERE IS A CONSIDERABLE LENGTH IN PROPORTION IT`S BREADTH.

WHIPPING STRESS the transverse component of force acting on connecting rod tries to bend the conrod in the `s` shape.

Selection of material 

Medium carbon steel(carbon: .35%-.45%) for  industrial engines  Alloy

Steel(Nickel chromium / Chromium molybdenum) for automobile /aircraft engines.

Design procedure Design

for cross section of connecting rod

Design

for big & small end bearings

Design

for big end cap & bolts

Design for cross section of connecting rod 1. Consideration of buckling To make it`s strengthful both in xx Axis & YY Axis Equally I section is preferred. 2.Dimensions of cross-section



Pressure acting on connecting rod= Area of piston x Max. pressure acting on piston Determination of `t` Using Rankine`s formula. Dimensions of I section Thickness:t Width:4t Height:5t

Design for big & small end bearings For small end bearing : Max. Pressure acting = Area of piston x Max. Pressure acting on piston Pc=dp  x lp x (pb)p  l/d =1.5-2

For big end bearing : Max. Pressure acting = Area of piston x Max. Pressure acting on piston Pc=dc  x lc x (pb)c  l/d =1.25-1.5

Design for big end cap & bolts Role

of inertia force acting after exhaust

For  For Bolts: Pi :Inertia force[refer databook] (Pi)=  2(πd.d) σt /4

For Cap: Considering the load to be avg. of  Point load & U. Distributed load.

M b=     6 

manufacturing I. Drop Forging II. Outer surfaces left Unfinished