stress - in - motion (sim) technology in south africaasphalt.csir.co.za/sim/sim web/2001-cost...
TRANSCRIPT
COST 347 Meeting:27th June 2001
Cologne, Germany
Stress - In - Motion (SIM) Technology
in South Africa
Morris De Beer, CSIR Transportek,
South Africa
Layout of Presentation:Layout of Presentation:
• Background: South African Pavements
• Heavy Vehicle Simulator (HVS) and Stress-In-Motion (SIM) Equipment
• 3D SIM Results
• Conclusions
EXTENT OF PROVINCIAL EXTENT OF PROVINCIAL (RURAL) ROADS(RURAL) ROADS
Extent of the non-urban provincial road
network in SA is 580 000 km;
300 000 km of gravel roads;
57 000 km surfaced (paved) roads;
Note: 6 713 km National Roads;
Note: Current value of all provincial roads is R 205 bn (23 % of GDP);
Only 31 % in good to very good condition;
Approximately 40 % poor to very poor condition;
Therefore, immediate risk to loose R 80 bn of provincial road infrastructure – condition worsening by the day –loosing approx. R 10 bn annually - loose ALL provincial roads in 10 – 15 years !;
Deep rural connectors or access roads more a socio-economic issue.
CONDITION OF PROVINCIAL CONDITION OF PROVINCIAL (RURAL) ROADS (RURAL) ROADS
Stress - In - Motion(SIM)
Technology in South Africa
UNDERSTANDING TRAFFIC LOADING ON ROAD PAVEMENTS
EXAMPLES..
Sub-grade Failures….
Fatigue Cracking and aging
Delamination..
Potholes & Patching…
TyreSTyreSTyreS
TyreSTyreS
TyreS
TyreSTyreS
TyreS
TYRE MAINTENANCE ??
~ 20 %
Increase
in
20 Years
Truck Tyre Inflation Pressure in South Africa:
I believe that part of the problem is that :
“In Pavement Engineering, worldwide today,the representation of pneumatictyre/pavement contact stresses isoversimplified by using a circular discof uniformly distributed pressure,equal or less than the tyre inflationpressure”...Strong indications suggests that thismay be far from real - world conditions….
HVS Mark IV+
ACCELERATED PAVEMENT TESTING – 1999 INTERNATIONAL CONFERENCE
Vehicular Load Modes
ACCELERATED PAVEMENT TESTING – 1999 INTERNATIONAL CONFERENCE
/
NEW HVS MkIV (PLUS): TYPICAL DYNAMIC LOAD
HISTORY
50
55
60
65
70
75
10800 11800 12800 13800 14800 15800 16800
Load cycle 1 Load cycle 2
Turn-aroundarea
Turn-aroundarea
Turn-aroundarea
AverageLoad
Time [ms]
Dynamic Load (HVS Mk IV Plus)
ACCELERATED PAVEMENT TESTING – 1999 INTERNATIONAL CONFERENCE
Moving Dynamic Load
ACCELERATED PAVEMENT TESTING – 1999 INTERNATIONAL CONFERENCE
Uni-directional Load
ACCELERATED PAVEMENT TESTING – 1999 INTERNATIONAL CONFERENCE
Permanent Surface Deformation
ACCELERATED PAVEMENT TESTING – 1999 INTERNATIONAL CONFERENCE
1
1
.
0
11.00 - R22.5 RADIAL HVS TYRES (AFTER CULLINAN ROAD 2388 TESTS)
-Z
+Z
+X
-Y
+Y
-X
-X'
+X'+Y'
-Y'CONTACT
AREA
SIM-TYRE.PPT
Area of Interest :
315/80 R22.5 HVS Tyre ON VRSPTA
Direction
of
Traffic
Instrumented
Pins
356 mm
755 mm
pattern1.wmf
TOP VIEW OF THE VRSPTA MK II
TYREPATCH
TYREPATCH
TYREPATCH
425 /65 R22.5 HVS Tyre ON SIM SYSTEM:
EXAMPLE OF FOOTPRINT TO FOLLOW…..
CONTACT STRESS DATA (BOLD TYRE): Extreme LoadingVertical Stress Lateral Stress Longitudinal Stress
TYRE “FINGER PRINTING”: (HVS : SIM : 11R22.5 TYRE)
INFLATION PRESSURE
LOAD
4 PAD SIM “FIELD” SYSTEM
VRSPTA Mark III
4 PAD SIM SYSTEM – most advanced
Deflectograph Truck (80kN, 650 kPa):
Vertical Contact Stress
Deflectograph Truck (80kN,650 kPa):
Lateral Contact Stress
Deflectograph Truck (80kN,650 kPa):
Longitudinal Contact Stress
DEFLECTOGRAPH (OCTOBER 1998)
Test 038-z
0 200 400 600 800 1000 12000
20
40
60
80
100
Measured Tire Contact Stress (kPa)
% C
um
ula
tive F
req
uen
cy
Front Left Front Right Rear Left OuterRear Left InnerRear Right OuterRear Right Inner
Inflation Pressure 600 kPa 600 kPa 690 kPa 690 kPa 690 kPa 690 kPa
Tyre
520 kPa (Design)
600 kPa (Front)
690 kPa (Rear)
MANTSOLE TRAFFIC CONTROLL CENTRE
(TCC) ON NATIONAL ROAD NR 1 (N1)
Full Axle SIM
North
WEIGH- BRIDGE SITE FOR SIM AT MANTSOLE ON THE N1
MANTSOLE TCC
0
200
400
600
800
1000
1200
Pin numbers
Str
ess
(kP
a)
1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10 8 6 4 2
AXLE 5Vertical Maximum Contact Stress (kPa)
001-z
DMB 453 GPLeft Outer
Tyre
Left Inner
Tyre
Right Inner
Tyre
Right Outer
Tyre
COMPUTER ANALYSES
OF ROAD PAVEMENT
STRUCTURES
SYMPLISTIC ANALYSIS: MULTI-
LAYER - LINEAR - ELASTIC THEORY;
COMPLEX: FINITE ELEMENT
METHOD + NON – LINEAR - ELASTIC
THEORIES;
0
40
200
1 300
0 100600 1 300
Non-Uniform Vertical Stress
Tyre EdgeCCLL
Depth (mm)
Radial Distance (mm)
Lateral stress
FIGURE: 29
Axi-symmetrical Finite Element Model
used in this study
Colour maps of Shape distortion
(Symplectic Engineering Corporation)
REAL-TYREMODELED TYRE
100 kN Axle
25 kN 25 kN 25 kN 25 kNWHEELLOAD
RECOMMENDED (INTERIM) TYRE CONTACT STRESSES
Road
Category
[TRH4 (1996)]
Percentile
Values (%)
Contact
Stress
(kPa)
Load
Radius
(mm)
D 50 660 110
C 80 865 96
B 90 975 90
A 95 985 90
CONCLUSIONS AND RECOMMEDATIONS…..
1. SIM Technology resulted in improved pneumatic tyre/pavement contact stress definitions;
2. Tyres to be “finger printed” for pavement design;
3. Potential for more rational pavement design, performance and analysis methods;
4. Potential savings of ECUmillions, if effectively employed…
5. Safety: Need to test at higher speeds-including car tyres – Europe ? (TNO Automotive) - Gerotek !?;
6. Need for tyre test track of International standard ?;
7. Institute of tyre/pavement technology ??;
8. International Co-operation ?.
I Thank You all !!