2. EXPERIMENTAL & ANALYTICAL INVETIGATION OF THE PISTON SECONDARY MOTION
IN A DIESEL ENGINE
Software Used – ADAMS-Engine
Abstract
Piston secondary motion is a well known phenomenon in internal combustion engines which cause
friction and noise. This motion is caused from the clearance between the piston and the cylinder liner
and the force components on the piston causes piston lateral motion as well as rotational motion about
the piston pin axis. This motion is known as piston secondary motion which causes friction as well as
noise. As the piston moves from TDC towards BDC during the expansion stroke, the side force on the
piston changes the direction and increases the force magnitude due to the rise of combustion pressure.
This accelerates the piston laterally across the cylinder and the piston skirt impacts against the liner.
Several approaches were followed to minimize the piston secondary motion by varying the engine
geometry and operational parameters. Understanding the piston dynamics and secondary motion will
greatly help reduce the engine friction.
In this work, a previously developed analytical model has been validated for the piston secondary
motion under variable speed and load conditions to understand the piston motion. The simulation
model was developed for dry pattern with no lubrication (rigid body) and temperature parameter. The
piston secondary motion was measured using telemetric system and gap sensors for various load cases
and these results were compared with the simulated data. Further to provide more substantiation for
the model and to illustrate its effectiveness in engine analysis, a series of parametric studies were
performed on a variety of characteristics of the engine performance. The results show that some of
these parameters have profound effects on the frictional and impact forces at the piston-skirt/liner
interface.
ADAMS/Engine Assembly Model Telemetry Layout
Comparison of Piston Travel in Different Strokes Under Full Load Condition @ 1400 RPM
3. PISTON SKIRT DEFORMATION STUDY USING FEA
Software Used – Catia V5.
Abstract
For a vehicle engine, the piston is the essential part that bears heavy mechanical and thermal loads;
therefore it has very many influences on the reliability and durability of an engine. So the piston
greatly hinders the increase of power of an engine. Piston dynamics and friction are two important
characteristics determining the performance and the efficiency of an internal combustion engine. In
this project an approach to the behavioral analysis of the piston skirt is presented that is based mainly
on the Finite Element Method representation. The Finite Element Method was used to predict the
deformation of the piston skirt and also the stress distribution across the piston.
Piston Model Boundary Condition
Displacement & Stress Contour for Piston Deformation @ 3.8 Mpa Gas Pressure, 410 RPM
Displacement & Stress Contour for Piston Deformation @ 6 Mpa Gas Pressure, 1580 RPM
4. FATIGUE LIFE OF SOLDER BALLS IN A FLIPCHIP PACKAGE
Software Used – Hypermesh, Abaqus.
Abstract
In the development of packaging of electronics the main aim is to increase the packaging density,
improve the performance while still maintaining or even improving the reliability of the circuits. The
concept of flip-chip process where the semiconductor chip is assembled face down onto circuit board
is ideal for size considerations, because there is no extra area needed for contacting on the sides of the
component. The performance in high frequency applications is superior to other interconnection
methods, because the length of the connection path is minimized. Also reliability is better than with
packaged components due to decreased number of connections. In flip-chip joining there is only one
level of connections between the chip and the circuit board.
The objective of this work is to investigate the reliability of the flip chip package under completely
filled case and incomplete case in which the underfill is partially and completely removed. A nonlinear
finite element technique, in which the viscoplastic material properties (strain rate-dependent) of solder
balls and underfill are considered, is adapted to simulate the corresponding “cleaning” and “non-
cleaning” samples to assess the impact on solder interconnect reliability. The results of the analysis
reveals that the incomplete model decreases the mechanical stability and shortens the life time of the
flip chip package.
Flip-Chip Hypermeh Model with Complete Underfill Material & No Underfill.
Model with Underfill Model with no Underfill
Step
Plastic Strain Displacement (mm) Plastic Strain Displacement (mm)
1 .0193 .0241 .093 .0227
2 .0239 .024 .109 .0227
3 .0214 .00101 .0843 .00234
4 .0206 .000926 .0811 .00224
5 .0208 .024 .1 .0226
Comparing the result Parameters for the models with Underfill & no Underfill.
16 24.5
14
Max. Von Mises Stress (MPa)
24
mm)
12
23.5
-3
10
Displacement (10
8 23
6
22.5
4
22
2
0 21.5
11980 10438 9362 3000 118
Fatigue Life (Cycle)
Von Mises Stress Displacement
Life Cycle of Flipchip with & without Underfill. Stress & Displacement based on Underfill.
5. CRANKSHAFT DESIGN FOR V8 ENGINE
Software Used – Catia V5.
Abstract
The crankshaft for a V8 engine was designed using the fundamentals of engine dynamics & vibrations.
This project was accomplished as a requirement for a course work which involved in depth designing
from the fundamentals. After designing the base model it is refined with counterweights and balanced.
Finally, the torsional vibration and the critical speed of the crankshaft are determined.
Crankshaft & Flywheel Assembly with added counterweights.
First Natural Mode Second Natural Mode
1.2 1
1
0.5
0.8
R ela tive A m plitude
R ela tive A m plitude
0
0.6 0 1 2 3 4 5 6
0.4
-0.5
0.2
-1
0
0 1 2 3 4 5 6
-0.2 -1.5
Mass Number Mass Number
First & Second Natural Modes for the Masses in Crankshaft Flywheel Assembly.
To calculate the dynamic magnifier,
N cyl
r
1 θ 1
D = (48....58)
N cyl
∑ θz
z =1 1
D = (48....58) × 4.898 = 59......71
4
The amplitude of the vibration of the first mass is expressed as
Θ1 = 60 × 0.000622 = 0.03678rad
Θ1 = D Θ1 st
Θ 1 = 2 .1 °
The maximum value of the torque produced by torsional vibration at resonance may be estimated by
N cyl
r
θ
M max k
= D Mk ∑ z
z =1 θ1
M max 8
= 60 × 22.4797 × 4.97 = 6606.33Nm
6. OPTIMIZATION OF CALIPER HOUSING USIGN FEA
Software Used – Catia V5.
Abstract
In automobile design, structural analysis is the most important engineering process in developing a
high quality vehicle where the computer simulations have greatly enhanced safety, reliability and
comfort of today’s automobiles. Optimization has become critically important area of application in
the automotive industry. Structural optimization coupled with analysis is instrumental in driving the
design process so that the design targets are met in a timely fashion where the design targets include
minimization of vehicle weight.
In this present work a disc brake caliper has been analyzed and the regions of material removal have
been identified using FEA. The regions with least stress and deflection are identified and taken off
from the component iteratively and analyzed using CATIA. The modified caliper with weight
optimization by 20% has been validated for real working condition by standard validation. By virtue
of this redesign, material saving and hence cost savings have been achieved.
Rib Ventilation
hole
Lug
Cylinder
Carrier Bolt
Existing & Proposed Caliper Housing Model.
Displacement & Stress Contour for Existing Caliper Housing Deformation at 70 bar Brake Pressure.
Displacement & Stress Contour for Proposed Caliper Housing Deformation at 70 bar Brake Pressure.
7. COASTDOWN ANALYSIS FOR EXTREME WIND CONDITION
Software Used – Matlab, Simulink.
Abstract
The coastdown analysis is a technique for measuring real world drag that enables us to improve the
vehicle performance and efficiency. The results out of this technique are more realistic than other
methods, since product improvements which reduce road load such as improved tyre construction or
reduced aerodynamic drag are properly represented. This may seem to be an ideal way to infer the
aerodynamic drag since the actual road vehicle is in its natural environment. It is also not straight
forward as it is necessary to separate the aerodynamic resistance from the rolling resistance (the tyre
being the primary source).
Although the coastdown technique is not new, obtaining adequate test repeatability requires correction
of observed road loads to standard conditions. Previously there were many assumptions to perform a
coastdown and a few of them are:
1. Wind speed is steady.
2. Wind speed is less than car speed.
3. Aerodynamic yaw angles remain small.
This project is upgraded with features including headwind and crosswind components on an extremely
windy condition which play a very important role in absorbing most of the kinetic energy of the
vehicle during the coasting freely in newutral. To define the aerodynamic drag and rolling coefficients,
utmost care is taken from the inception of anemometer calibration. Also a huge role is played by the
simulated coastdown for analyzing the procedure. A new drag model is introduced for optimizing the
real data coefficients and the sensitivity analysis is achieved with the variation of the optimized
coefficients.
8. CHASSIS TORSIONAL STIFFNESS MEASUREMENT ON FORMULA SAE CAR
Software used – Nastran.
Abstract
Finite element analysis is a very powerful engineering design tool that enables engineers and designers
to simulate structural behavior, make design change and distinguish the effects of these changes. FEA
is in effect a computer simulation of the whole process in which a physical prototype is built and
tested, and then rebuilt and retested until an acceptable design in created. Clearly, this physical process
can be costly and time consuming when compared with running a computer simulation. However,
FEA is not meant to replace prototype testing, merely to complement it. Testing is a means of
validating the computer model. In certain cases it can be impossible to accurately model a complex
real life situation.
This work deals with the investigation of torsional stiffness of a chassis frame structure for a Formula
SAE car. The stiffness matrix is framed for the particular beam with fundamentals of frame element
theory. The cutting edge of Nastran in used to design the chassis frame and it is observed for the
deflections experienced for the loads applied in a particular section of the chassis.
