Dr. Prashanth Ramachandran has experience designing and analyzing mechanical systems, precision actuators, linkages, and equipment for industries such as oil/gas, electronics, automotive, and more. His analysis experience includes finite element analysis of structural and thermal systems, stability theory, and numerical techniques. He has expertise in fields like classical mechanics, heat transfer, and project management. Some of his recent projects include designing iPad battery covers, hydrocracker equipment, servo control systems, and automotive synchronizer hubs.

1. Sample of projects performed in recent years
Presented by
Dr. Prashanth Ramachandran

2. Job Portfolio
 Design –
o Mechanical system
o Precision actuators
o Hydraulic, Pneumatic (0.5” to 30” bore)
o Mechanical linkages with high D.O.F
o Steering control mechanism, Harmonic (base) excitation
o Electronics industry
o Gyroscopic mount for camera, Battery cover with spring back,
o Oil/gas equipment
o Piping design
 Analysis
o Finite Element Analysis (Structural)
o Linear
o Static, Dynamic (Harmonic, Random Response-Frequency Extraction, Buckling)
o Nonlinear
o Static (Geometry, Contact, Materials)
o Dynamic (Implicit and Explicit)
o Material Models used include; Elastic-Plastic, Hyper Elastic (Mooney-Rivlin, Arruda
Boyce)
o Finite Element Analysis (Thermal)
o Sequential/Fully Coupled Thermal-Mechanical Analysis

3. Fields of Expertise
 Classical Mechanics -
o Euler-Lagrange formulation
o Lagrange multipliers
o Principle of virtual work
o Vibration theory
o Harmonic base excitation, General excitation by Laplace transform,
Complex excitation, Dynamic absorber
 Stability Theory -
o Feedback control system with time delay
o Root-locus, Routh-Hurwitz
o Pole placement, Inverse problem, Buckling
 Numerical Technique -
o Matrix manipulation
o (SVD, LU, QR)
o Calculus of Variation (Brachistocrone problem)
o Gauss Quadrature
 Fundamental Heat Transfer -
o Steady state and forced convection
 Project Management
o Code Expertise

4. Design/Analysis/Testing
Precision Actuators
Sectional View of an Actuator

5. Reliability Testing
Problem of Least Squares
Methodology
bAx  minimizeswhich,vector xaFind n
  nm
n
x
21 ...where,  aaaA m
b
Mathematically bAx
x
min
From Euclidean Norm
    bbbAxAxAxbAxbAxbAx TTTTTT
 2
Minimizing   0bAAxA
x
bAx


 TT
22
  bAbAAAx 
 TT 1
(Vandermonde
Matrix)
FEA
Gland - Shear
Damage Percentage Life
Fatigue Strength – Retaining Ring

6. Design/Analysis
Electronics Industry
IPad 2 Battery Cover
Design Consideration
The primary motivation of this study was to design/evaluate the
‘snap’ feature for assembly of ‘tilt module’ into the ‘base’.
AISI 1022 Steel - Screw
Snap – Beryllium Copper
Al 6061-T6 – Tilt Module
Al 5052-H32 – Base
Poron - Foam
Snap Mechanism
High speed, low strain rate event with minimum energy dissipation
Dynamic, Implicit analysis
Problem unconditionally stable
Global set of equations solved rather than the kinematic
state of the problem at every advancing step
Snap
Interactions
Slave Surface
Master Surface

7. Electronics Industry
IPad Battery Cover
Analysis - ResultsA maximum stress of 28.16 MPa was observed on
the snap during the engage which is well below
the yield stress of beryllium copper (258 MPa).
A maximum contact pressure of 34.641 MPa was
observed on the snap during the engage.
The displacement profile of the entire assembly
once the snap has completely engaged in the shelf

8. Design/Analysis
Oil/Gas
Hydrocracker – Sequentially Coupled Thermal Mechanical Analysis
Design Motivation
XXXX has a gas oil hydrocracker unit at its XXX refinery, where a
catalytic converter had to be designed and analyzed.
AnalysisGeometryRegime
Vessel Detail
Top Head
Bottom Head

9. Oil/Gas
Hydrocracker – Sequentially Coupled Thermal Mechanical Analysis
Results
SA-387-GR-11-CL2 - Shell / Heads
SA-182-F11-CL2 - Nozzle Pipe
Sintered Alumina - Catalyst Bed
Guard Bed Reactor
Radial Stress
Location of
maximum stress
Temperature
Distribution
Location of
maximum stress
Axial Stress Hoop Stress
Location of
maximum stress

10. Design/Testing
RC Servo Control Motors Time Delay
Adaptive Filament Winder – 2 axis Gimbal
Design Consideration
Pay load
Fiber tension
Rotational range
Time delay of RC servo motors
2-axis accelerometer
2-axis magnetometer
Component Plate and
Camera Mount
The translational and rotational speeds had to be maintained with a high degree of accuracy as they determine the winding angle of the
fiber. This was done with 2 gyroscopes, one 2-axis accelerometer, and one 2-axis magnetometer. The RC servo motors were actuated by a
MATLAB code that took the time delay in a closed loop control system into account.
Camera Mount

11. Servo Control Motors Time Delay
Adaptive Filament Winder, Gyroscopic Mount – 2 axis Gimbal
Analytical Treatment

12. Servo Control Motors Time Delay
Adaptive Filament Winder – 2 axis Gimbal
Analytical Treatment
Equations of Motion
Characteristic Equation
by substituting
where

13. Stability Theory
Electronics Industry
IPhone 5S Display
Portrait
Landscape
45°
Why did the image (Google) not rotate by 45° when the coordinates of the phone were rotated by 45°?

14. Problem Definition
State Feedback Control
ModelSystem
uBAxx 
LawControl
F
feedbackstateFull
u x
Block diagram of state feedback control
- Time Delay Ackermann’s Formula
 APψeF n
1

 Tn
BABAABBψ 12 
 
     
0
2
2
1
1
1
 







n
n
n
n
n
n
sss
pspssP
 1000 ne
There is an inherent time delay between the measure of
state and the application of the control force.

15. Motivation
Newton’s Method




































333
222
111
fff
fff
fff
J
Problem of
e.g. Maple Solution
 
   ;,, lambdaconjugatelambdatauf
lambdaconjugate

Error , invalid derivative
    ;*2*5*3:,, lambdaconjugatelambdataulambdaconjugatelambdatauf 
3τ + 5λ + 2λ
   ;,, lambdaconjugatelambdatauf
tau

3
   ;,, lambdaconjugatelambdatauf
lambda

5 - 2λ + 4 abs (1,λ)
λ signum (λ)
 
   lambdaconjugatelambdatauf
lambdaconjugate
,,


Not differentiable w. r. t.
complex variables

16. SIMO System
 tu
 tx1
 tx2
 tu tu
 tx1
 tx2
 tu
   0vgfbKCM   TT
e  2
First Order Realization






































0
0
v
v
bfbg
00
M0
0I
CK
I0

 
TT
e
A  B 
 e H y 0( )
(or)
Non-Trivial Solution
  0det  
HBA 
 e
0y  if and only if
Transcendental Characteristic Equation
        tuttt bKxxCxM 
nnn 1
,,, 
 bKCM

17. Generalized Solution for SIMO System
Then when λ is imaginary we have
        DDNN  ˆ,ˆ
   
,
2arg
k
k
kr
irP




 ...1,0,1...r

18. Design
Automotive Industry – Synchronizer Hub
3 stage synchronizer hub – Powder metallurgy
Transmission shaft– Cold forging
Exploded view of a 3 cone synchronizer hub
Engagement ring Inner ring Intermediate ring Blocker ring Sleeve Hub Detent
Design Consideration
Inertia to be synchronized
Torque to be transmitted
Speed difference to be synchronized
Interfaces (spline data, sleeve groove, clearance of gear wheels
Installation space
Limiting Factors
Torque capacity of sleeve/hub-system and engagement ring
Capacity of friction material (sliding speed, surface pressure,
friction power)

19. Code Expertise
 ASME
o Section II-D Boiler and Pressure Vessel Code
o Section VIII Division I Boiler and Pressure Vessel Code
o Section VIII Division II Boiler and Pressure Vessel Code
o B 31.3 Code for Process Piping
o B 31.1 Code for Power Piping
o B 16.9 Butt welding Fittings
o B 16.5 Pipe Flanges and Fittings
 API
o 579 Fitness for Service
o 571 Damage Mechanisms in Fixed Equipment
o 570 Piping Inspection
o 610 Centrifugal Pumps for Petrochemical Industries
o 650 Welded Tanks for Oil Storage
o 653 Tank Inspection
o 5C5 Casing and Tubing Connections

20. Questions ??
Dr. Prashanth Ramachandran
Prashanth8.84@gmail.com
+1-(848)-702-5764