Punit Kumar is professor at NIT KKR.

1. Associate Professor (Present Permanent Position)
Mechanical Engineering Department
National Institute of Technology, Kurukshetra
Currently working as:
Professor (On Lien)
Malaviya National Institute of Technology Jaipur
Dr. Punit Kumar

2. RESEARCH AREA
TRIBOLOGY – ELASTOHYDRODYNAMIC LUBRICATION
PHD THESIS TITLE
SURFACE ROUGHNESS EFFECTS IN MIXED RHEOLOGICAL
THERMO-EHL ROLLING/SLIDING LINE CONTACTS
X
-2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0
P
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8

3. 3
EHL LINE CONTACT MODEL FOR
SHEAR-THINNING FLUIDS USING
GENERALIZED NEWTONIAN
(EXACT) APPROACH

4. LINE CONTACTS – TEHL Model….
Rheological Model : Carreau Viscosity
 
 
2
1
2
1
2
1
2 1
/






















n
cr
G









1

Where, is first Newtonian Viscosity at low shear rates,
2
 is the second Newtonian viscosity at high shear
rates
y
u 

 /

 is the shear rate ,
n is the power law index,
M
R
Gcr

 .
 is the critical stress

5. Generalized Reynolds Equation
where and
2
4







W
U
K
  
o
u
u
u
S 1
2 

dY
F 

1
0
0
1

dY
Y
F 

1
0
1 .

dY
F
F
Y
Y
F  









1
0 0
1
2

LINE CONTACTS –TEHL Model…
  
























0
1
2
3
2
1
2 F
F
H
X
S
K
H
X
K
X
P
F
H
X












6. LINE CONTACTS – TEHL Model
Boundary conditions
Inlet : P=0 at X = Xin
Outlet : P = dP/dX = 0 at X= Xo
Film thickness equation
v
where
  v
X
H
X
H o 


2
2
= Elastic deformation

7. Load Balance Equation : w
pdx
x
xin
 
0
Where,
w=Applied Load per unit length
Density-pressure relationship:












 

p
p
9
9
0
10
7
.
1
1
10
6
.
0
1


Where,
0
 =Density at atmospheric pressure
LINE CONTACTS – TEHL Model…

8. Viscosity-Pressure Relationship:
Barus relationship :
 
p


 exp
0

Roelands Equation:
   
 
 
z
o p
9
0 10
1
.
5
1
1
67
.
9
ln
exp 






 


Where,
0
 =Viscosity at ambient pressure
Where,
 
67
.
9
ln
10
1
.
5 0
9


 


z
 =Pressure viscosity coefficient
LINE CONTACTS – TEHL Model..

9. RESEARCH@LSU (USA)
Developed a new thermal EHL model considering realistic
shear-thinning behavior.
Developed an EHL model for point contacts and derived
correlation formulas for shear-thinning correction factors
Achieved good agreement between numerical results and
experimental film thickness data pertaining to shear-thinning
lubricants
Presented the first-ever full EHL line and point contact
simulations using “Actual” Ree-Eyring model
 Developed the first-ever equation for EHL traction coefficient
 Investigated and quantified the effect of starvation on EHL
traction coefficient and film thickness for Carreau-type shear-
thinning lubricants

10. INTERNATIONAL COLLABORATION
Investigated the effect of scale and load EHL film thickness
for lubricants with varying extents of shear-thinning behavior
Developed EHL film thickness equations for lubricants with
linear pressure-viscosity relationship
Investigated anharmonic variation of EHL film thickness due
to harmonically varying rolling speed considering fragility
effect in Transient-Thermal-EHL line contact simulations
Investigated the role of lubricant properties and
mathematical models on the thermal EHL characteristics.

11. INTERNATIONAL COLLABORATIONS
Investigated the effect of scale on EHL film thickness for lubricants
with varying extents of shear-thinning behavior
Rolling speed, m/s
0.001 0.01 0.1 1
Central
film
thickness,
nm
10
100
1000
Experiments (35 mm ball)
Experiments (25.4 mm ball)
Experiments (9 mm ball)
Experiments (5.5 mm ball)
EHL point contact simulations
Hamrock-Dowson
Mineral oil at 40C
35 mm
25.4 mm
9mm
5.5 mm
Rolling speed, m/s
0.001 0.01 0.1 1
Central
film
thickness,
nm
10
100
1000
10000
Experiments (35 mm ball)
Experiments (25.4 mm ball)
Experiments (9mm ball)
Experiments (5.5 mm ball)
EHL point contact simulations
Hamrock-Dowson
PAO mixture at 50C
35 mm
25.4 mm
9 mm
5.5 mm
35 mm
25.4 mm
9 mm
5.5 mm
Rolling speed, m/s
0.001 0.01 0.1 1
Central
film
thickness,
nm
10
100
1000
10000
Experiments (35 mm ball)
Experiments (25.4 mm ball)
Experiments (9 mm ball)
Experiments (5.5 mm ball)
EHL point contact simulations
Hamrock-Dowson
Gear oil at 50C
35 mm
25.4 mm
9 mm
5.5 mm
35 mm
25.4 mm
9 mm
5.5 mm
Published in Tribology
Letters , Springer

12. INTERNATIONAL COLLABORATIONS
Investigated the effect of load on EHL film thickness for lubricants
with varying extents of shear-thinning behavior
x (m)
-200 -150 -100 -50 0
Inlet
zone
shear
stress
(MPa)
0
1
2
3
4
12 N
85 N
LF5346
Rolling speed (m/s)
0.01 0.1 1
Central
film
thickness
(nm)
10
100
1000
Experiments (12 N)
Experiments (85 N)
Experiments (195 N)
EHL Point Contact Simulations
Newtonian
195 N
85 N
12 N
12 N
85 N
195 N
PG460
Rolling speed (m/s)
0.01 0.1 1
Central
film
thickness
(nm)
10
100
1000
Experiments (12 N)
Experiments (85 N)
Experiments (195 N)
EHL Point Contact Simulations
Newtonian
195 N
85 N
12 N
SR600
Rolling speed (m/s)
0.01 0.1 1
Central
film
thickness
(nm)
10
100
1000
Experiments (12 N)
Experiments (85 N)
Experiments (195 N)
EHL Point Contact Simulations
Newtonian
195 N
85 N
12 N
hc ∝ pH
-l
Oil l
SR600 0.19
PG460 0.28
LF5346 0.31
Published in Tribology Letters , Springer

13. 13
INTERNATIONAL COLLABORATIONS
Line Contacts
646
.
0
198
.
0
197
.
0
732269
.
4 U
W
G
R
h
B
c 

0.598 0.178 0.11
1.858
c
x
h
U G W
R


Point Contacts
Rolling speed (m/s)
0.01 0.1 1
Central
film
thickness
(nm)
1
10
100
1000
DMP - Measured
DMP - Simulated
DMP - Correlation Eq. (12)
S40 - Measured
S40 - Simulated
W=5.2x10-4
U
10-13 10-12 10-11 10-10
h
min
/R
10-7
10-6
10-5
10-4
Curve-fitted
Simulated
Dowson Higginson Eq
(B=20GPa
-1
)
(B=20GPa
-1
)
(B=8GPa
-1
)
(B=2GPa
-1
)
Developed EHL film thickness equations for lubricants with linear
pressure-viscosity relationship
Published in Tribology International, Elsevier

14. INTERNATIONAL COLLABORATIONS
Investigated anharmonic variation of EHL film thickness due to
harmonically varying rolling speed considering fragility effect in
Transient-Thermal-EHL line contact simulations
PAO at 50 Hz
R=0.0095 m, E=290 GPa
Time (ms)
0 5 10 15 20
Central
film
thickness
(nm)
120
140
160
180
200
220
240
Entrainment
velocity
(m/s)
0.05
0.10
0.15
0.20
0.25
Central film thickness
Entrainment velocity
5P4E at 50 Hz
R=0.0095 m, E=290 GPa
Time (ms)
0 5 10 15 20
Central
film
thickness
(nm)
160
180
200
220
240
260
280
Entrainment
velocity
(m/s)
0.05
0.10
0.15
0.20
0.25
Central film thickness
Entrainment velocity
Published in IMechE J. of Tribology

15. RESEARCH SUPERVISION
Developed design equations to calculate EHL film thickness:
For shear-thinning lubricants (Line & Point contacts)
For linear piezo-viscous oils (Line contacts)
For pressurized ambient conditions
For lubricants with second Newtonian shear-thinning
Compared time-dependent EHL film thickness behaviors
pertaining to oils with different rheology for:
Spur gears & Film collapse due to sudden arrest of motion
Repeated impact load
Accelerated motion
New EHL model with limiting shear stress & interfacial wall slip
Introduced the concept of inlet zone bump for better
performance

16. Sponsored Projects
Sponsoring
Agency &
Status
Description / Title of Project
Czech Ministry of
Education
(Completed)
Indo-Czech Project on Joint Internal
Cooperation in S&T
Naval Research
Board
(Approved)
Design, Fabrication and Testing of
Active Magnetic Bearings
ARMREB, DRDO
(Sanctioned-
Reapplied-Under
Review)
Synthesis and Characterization of
Ceramic-Metal FGM Armors With
Improved Ballistic Performance

17. 17
IPR – Design Reg. No. 253848
(Patent Office, Govt. of India)
Step Escalating Wheeled Assistance (SEWA)
A wheel chair to assist people with locomotive disabilities
while climbing steps or overcoming obstacles on uneven
roads.

18.  To work on the design and development of:
 Active Magnetic Bearings
 Artificially textured surfaces for EHL applications
 Artificial human joints with improved tribological
performance.
 Magnetic levitation based manufacturing systems
 New armor materials
 Autonomous stair-climbing wheelchair
 To establish an Advanced Research Centre aimed
at development of indigenous capabilities in
important S&T areas wherein we depend on
imported technologies
FUTURE PLANS

19. TEACHING EXPERIENCE
 Courses Taught
•Advanced Mechanics of Solids (PG)
•Computer Aided Design – Geometric Modeling (UG + PG)
•Tribology (UG)
•Robotics (UG + PG)
•Material Science (UG)
•Concepts of Engineering Design (PG)
 Teaching Innovations
•Developed simulation codes for visualization
•Learning through Group Discussions
•Assignments of Short Term Projects

20. ADMINISTRATIVE EXPERIENCE
 Institute Level
•Professor-in-Charge, Hiking & Trekking Club
•Member, Innovation Club
 Department Level
•Professor-in-Charge, Tribology Lab
•Professor-in-Charge, Computer Lab
•Convener, Information Committee
•Member, Departmental Research Committee
•Convener, Departmental Purchase Committee (MNIT Jaipur)

21. OTHER PROFESSIONAL ACTIVITIES
 Reviewed several research papers for journals published by
ASME, STLE and Elsevier
 Organized a self-financed Short Term Course on “CFD
Applications in Tribology”
 Delivered an expert lecture on “Application of CFD in
Hydrodynamic Lubrication” at UIET, Kurukshetra University
in 2014
 Delivered an expert lecture on “Modeling of EHL Considering
Realistic Conditions” in 2015
 Life Member, Tribology Society of India
 Life Member, Institution of Engineers (India)

22. Thank You