Investigation of the Mechanics of Rail Seat

ovariesracialUrban and Civil

Nov 25, 2013 (3 years and 6 months ago)

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Ryan
G.
Kernes
,
Amogh

A.
Shurpali
, J. Riley Edwards,


Marcus S.
Dersch
, David A. Lange, and Christopher P.L.
Barkan

International Concrete Crosstie & Fastening System Symposium

Urbana, IL

6
-
8 June 2012

Investigation of the Mechanics of Rail Seat
Deterioration (RSD) and Methods to Improve the
Abrasion Resistance of Concrete Sleepers

Slide
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Investigating Rail Seat Deterioration

Outline


Objectives


Rail seat deterioration
(RSD) background


Large scale abrasion test


Evaluation of frictional
properties


Small scale abrasion
resistance test


Results


Conclusions and future work

Slide
3

Investigating Rail Seat Deterioration

Objectives


Understand the mechanics of
the most critical failure modes


Investigate parameters that
affect abrasion mechanism


Characterize frictional forces
between rail seat and rail pad


Propose methods of mitigating
the critical failure modes


Quantify abrasion resistance
of various concrete mix
designs, curing conditions,
and surface treatments

Slide
4

Investigating Rail Seat Deterioration

Rail Seat Deterioration (RSD)


Degradation of concrete material
under rail and pad


Increases maintenance costs


Shortens service life of the
concrete crosstie


Leads to track
geometry
defects



Feasible mechanisms:


Abrasion


Crushing


Freeze
-
thaw damage


Hydro
-
abrasive erosion


Hydraulic pressure cracking

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5

Investigating Rail Seat Deterioration

Abrasion Mechanism of RSD


Abrasion is a progressive failure mechanism that occurs when:


Frictional forces act between two surfaces in contact


Relative movement occurs between the surfaces


Harder surface cuts or ploughs into softer surface



Progression of abrasion at the rail seat

1.
Cyclic motion of rail base induces shear forces

2.
Shear forces overcome static friction

3.
Pad slips relative to concrete

4.
Strain is imparted on concrete matrix



Abrasion
involves 3
-
body
wear: two
interacting surfaces (rail pad
and rail seat)
and abrasive
slurry (water and fines)


Slide
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Investigating Rail Seat Deterioration

Large Scale Abrasion
Resistance
Test
Experimental Setup

Vertical
Actuator

Horizontal
Actuator

Abrasion Pad

Concrete
Specimen

Slide
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Investigating Rail Seat Deterioration

Large Scale Abrasion Resistance Test Results


Consistently able to cause deterioration of concrete due to abrasion


Concrete deterioration initiates near pad edges and propagates inward


Heat build up in pad materials at local contact points leads to softening
and adhesion to concrete surface


Difficulty in correlating severity of abrasion to input variables


Contact angle and pressure distribution


Heterogeneity of concrete surface

Slide
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Investigating Rail Seat Deterioration

Experimental Evaluation of Friction


Magnitude of static frictional force is directly related to
the normal force between the two bodies by the

coefficient of friction (μ)


Experimental
frictional coefficient measured during
test calculated
by:

μ
=
|
𝑭
|/
𝑷


where F is the force required to initiate lateral
sliding under vertical normal load
P


400
loading cycles to simulate single
unit train
pass


5,000 pound normal vertical
load (420 psi),
1/8” lateral
displacement, 3 cycles/second, no abrasive fines or
water added


Slide
9

Investigating Rail Seat Deterioration

Mean Coefficient of Friction per Loading Cycle

Polyurethane

Nylon 6/6

Slide
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Investigating Rail Seat Deterioration

Effect of Environmental Conditions on Nylon 6/6








Sand
Water
No
No
No
Yes
Yes
Yes
Slide
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Investigating Rail Seat Deterioration

Effect of Environmental Conditions on

Concrete Abrasion

Polished surface with no sand

Abrasion initiated with sand

Slide
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Investigating Rail Seat Deterioration

Effect of Increasing Normal Load on Nylon 6/6

5 kips

3 kips

10 kips

Slide
13

Investigating Rail Seat Deterioration

Small Scale Abrasion Resistance Test
(SSART): Test Setup


In general, similar to other
standard abrasion tests


Consists
of
powered
rotating
steel wheel with 3
lapping rings


Lapping
rings permitted
to rotate about their
own
axis


Vertical load applied
using the dead weights


Abrasive sand and
water dispensed
during testing

Slide
14

Investigating Rail Seat Deterioration

Test Protocol


Each test can evaluate 3 specimens


Multiple tests are run to evaluate
more than 3 specimens


Specimen dimensions:
4 inch (diameter),1 inch (thickness)


Duration: 120 minutes


W
ear depth measurements taken
every 20 minutes


Speed: 60
revolutions per minute


Abrasive fine: Ottawa 20
-
30 sand


Before

After

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Investigating Rail Seat Deterioration

Test Variables


Admixtures


Silica fume: 5%,10%


Fly ash: 15%, 30%



Curing
Condition


Moist


Submerged


Oven dry


Air






Surface Treatment


UV epoxy


Polyurethane


Grinding


Fiber
Reinforced Concrete (FRC)


Polyurethane


Steel





Slide
16

Investigating Rail Seat Deterioration

Effect of Mineral Admixtures

Slide
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Investigating Rail Seat Deterioration

Effect of Fiber Reinforcement

Slide
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Investigating Rail Seat Deterioration

Effect of Curing
C
onditions

Slide
19

Investigating Rail Seat Deterioration

Comparison of Techniques to Increase Abrasion
Resistance

Slide
20

Investigating Rail Seat Deterioration

Additional Tests Conducted


Objective: to obtain specimens batched by industry concrete
crosstie suppliers


Silica fume and epoxy coated specimens tested


Saw
-
cut surface of control specimens considered analogous to
ground surface and tested






















Grinding

Epoxy coating

Slide
21

Investigating Rail Seat Deterioration

Effect of Surface Treatments

Slide
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Investigating Rail Seat Deterioration

Conclusions


Large scale testing:


Confirmation
of abrasion as a feasible RSD
mechanism


Frictional
coefficient is affected by temperature, water, sand,
normal force


SSART:


Successfully compared 13 approaches to improving abrasion
resistance of rail seat through material improvements


Improve abrasion resistance of concrete with:


Optimal amounts of fly ash


Proper curing condition


Addition of steel fibers


Grinding cement paste



Slide
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Investigating Rail Seat Deterioration

Future Work



Determining the optimal frictional properties at each interface of
multi
-
layer
rail pads
(top, bottom, and between layers) could:


Reduce movement at critical interfaces


Influence load path and location of slip


Delay the onset of abrasive
wear and extend rail seat life


Extend
to other fastening system components


SSART:


Perform image analysis to characterize the role of coarse
aggregate in abrasion resistance


Study the effect of air
entrainment
and quality of aggregates on
abrasion resistance of rail seat


Use of Statistical Analysis Software (SAS) to model abrasive
wear
of concrete specimens


Optimize concrete mix design
and surface treatments to
mitigate
abrasion




Slide
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Investigating Rail Seat Deterioration

Acknowledgements


Funding for this research has been provided by


Association of American Railroads Technology Scanning Program


NEXTRANS Region V Transportation Center


Eisenhower Graduate Fellowship


For providing direction, advice, and resources:


Amsted Rail
-

Amsted RPS: Jose
Mediavilla
, Dave
Bowman, Brent Wilson,


BNSF Railway:
John
Bosshart
, Tom
Brueske
, Hank Lees


AREMA Committee 30: Winfred

Boesterling
,

Pelle

Duong, Kevin Hicks, Tim Johns,
Steve Mattson, Jim Parsley, Michael
Steidl
, Fabian Weber, John
Zeman


TTCI: Dave Davis, Richard
Reiff


Pandrol

Track Systems: Bob Coats, Scott
Tripple


UIUC: Tim
Prunkard
, Mauricio Gutierrez, Don Marrow,
Darold

Marrow


For assisting with the research and lab work:


Josh Brickman, Ryan Feeney
, Kris
Gustafson, Steven
Jastrzebski
, Andrew

Kimmle
, Calvin Nutt, Chris Rapp,
Amogh

Shurpali
, Emily
Van
Dam, Michael
Wnek

Slide
25

Investigating Rail Seat Deterioration

Questions

Ryan
Kernes

Research Engineer

Rail Transportation and Engineering Center
-

RailTEC

email
: rkernes2@illinois.edu



Amogh

A.
Shurpali

Graduate Research Assistant

Rail Transportation and Engineering Center
-

RailTEC

email
:
ashurpa2@illinois.edu