78th TRB 99 Session 440

Transcription

1 ICAP 97 78th TRB 99 Session 440 Latest Developments on Tyre Road Surface Interface Stress Measurements Using the 3-D Cell (PP ) Morris De Beer () Louw Kannemeyer (SANRA Ltd)

2 (1st Reference: 8th ICAP 97- Seattle, USA ICAP 97 Stress - In - Motion (SIM)N, Transportek, South Africa

3 ICAP 97 RUTTING

4 ICAP 97 Longitudinal Flow of Asphalt

5 ICAP 97 Fatigue Cracking and aging

6 ICAP 97 SURFACE DISINTEGRATION

7 ICAP 97 TIRES

8 ICAP 97

9 ICAP 97

10 ICAP 97

11 % OF TYRE PRESSURE 25 ICAP Average: 620 kpa (1974) Average: 733 kpa (1995) TYRE INFLATION PRESSURE (kpa) FIGURE 1a Tyre inflation pressure distributions in South Africa ( )

12 Heavy vehicles: Axle Loads > kg Survey: 1995 ICAP % 9.7% 38.5% 13.8% 3.6% 33.2% R R R /80-315/80 R /80-445/65 R22.5 FIGURE 1b Distribution of heavy truck tyre types in South Africa

13 VERTICAL CONTACT STRESS (kpa) ICAP 97 Direction of travel TYRE ON HVS (or Vehicle) VRSPTA X Y Pavement Surface Computer set-up Z SMOOTH TYRE - Z DIRECTION (CREEP SPEED) (JUNE 1994) LOAD 20kN VRSPTA PIN NUMBER FIGURE 2 Schematic layout of VRSPTA system

14 VEHICLE-ROAD SURFACE PRESSURE TRANSDUCER ARRAY (VRSPTA)

15 315/80 R22.5 HVS TYRE ON VRSPTA

16 425 /65 R22.5 HVS TYRE ON VRSPTA

17 VRSPTA PIN OUTPUT (NEWTON) ICAP Data Regression VOLTAGE FIGURE 3 Laboratory calibration data of VRSPTA pins

18 17 mm 15 mm ICAP 97 Effective Area = 250,28 mm 2 Direction of tyre movement Support pins Instrumented pins FIGURE 4 Effective Diamond Shaped Area used for the contact stress calculation in VRSPTA

19 VRSPTA MEASURED LOAD (kn) Tyre Type VI TRAFFIC SPEED ( m/s) ICAP r 2 = Std. Error of Y. = 4.3 kn HVS APPLIED LOAD (kn) FIGURE 5 Accuracy of the VRSPTA relative to HVS applied load (random error)

20 ICAP 97

21 VERTICAL CONTACT STRESS, q (kpa) x ply smooth HVS Tyre ICAP AVERAGE (1974) TYRE INFLATION PRESSURE, p (kpa) FIGURE 10 Average vertical contact stress vs inflation pressure MAXIMUM 95 P 90 P 80 P 50 P

22 ICAP 97

23 ICAP 97 VRSPTA Mark III

24 CONTACT STRESS (kpa) Tyre Load = 18 kn INFLATION PRESSURE:: 420 kpa 520 kpa 620 kpa 720 kpa ICAP Tyre width: 220 mm PIN NUMBER ACROSS VRSPTA FIGURE 11 Maximum vertical stress at CONSTANT LOAD and various inflation pressures

25 CONTACT STRESS (kpa) Tyre Load = 49 kn Tyre width: 220 mm INFLATION PRESSURE: 420 kpa 520 kpa 620 kpa 720 kpa ICAP PIN NUMBER ACROSS VRSPTA FIGURE 12 Maximum vertical stress at CONSTANT LOAD and various inflation pressures

26 CONTACT STRESS (kpa) 1600 INFLATION PRESSURE = 420 kpa ICAP WHEEL LOAD: 20kN 30kN 40kN 50kN Tyre width: 220 mm PIN NUMBER ACROSS VRSPTA FIGURE 13 Maximum vertical stress at CONSTANT INFLATION PRESSURE at various loads

27 CONTACT STRESS (kpa) INFLATION PRESSURE = 620 kpa WHEEL LOAD: 20kN 30kN 40kN 50kN Tyre width: 220 mm ICAP PIN NUMBER ACROSS VRSPTA FIGURE 14 Maximum vertical stress at CONSTANT INFLATION PRESSURE and various loads

28 CONTACT STRESS (kpa) Tyre Load = 20 kn ICAP TYRE INFLATION PRESSURE: 420 kpa 520 kpa 620 kpa 720 kpa PIN NUMBER OF VRSPTA FIGURE 16 Maximum vertical stress of tyre with tread grooves at CONSTANT LOAD and various inflation pressures

29 CONTACT STRESS (kpa) ICAP INFLATION PRESSURE = 520 kpa TYRE LOAD (kn): PIN NUMBER OF VRSPTA FIGURE 17 Vertical stress of tyre with tread grooves at CONSTANT INFLATION PRESSURE and various loads

30 % CUM FREQUENCY X PLY TYRE WITH TREAD ICAP TYRE LOAD: 14 kn 17 kn 31 kn 40 kn kn INTERVAL MIDPOINT CONTACT STRESS (kpa) FIGURE 19 Cumulative frequency of maximum vertical stress

31 ICAP 97 DIRECTION OF TRAVEL MEASURED VERTICAL CONTRACT STRESS VALUES FIGURE 25d Patch area = mm 2 Typical measured tyre contact patch

32 VERTICAL CONTACT STRESS (kpa) 1200 TYRE TYPE I (HVS SMOOTH) (11.00 X 20, 14 Ply) ICAP Inflation Pressure: 400 kpa 600 kpa 800 kpa SINGLE TYRE LOAD (kn) FIGURE 26a Maximum vertical stress vs tyre load

33 VERTICAL CONTACT STRESS (kpa) TYRE TYPE II (HVS - WITH TREAD) (11.00 X 20, 14 Ply) ICAP Inflation Pressure: 800 kpa 600 kpa 400 kpa SINGLE TYRE LOAD (kn) FIGURE 26b Maximum vertical stress vs tyre load

34 VERTICAL CONTACT STRESS (kpa) TYRE TYPE III (AIRCRAFT TYRE) Inflation Pressure: 1448 kpa ICAP SINGLE TYRE LOAD (kn) FIGURE 26c Maximum vertical stress vs tyre load

35 VERTICAL CONTACT STRESS (kpa) TYRE TYPE IV (315/80 R22.5) Inflation Pressure: ICAP kpa 1000 kpa 800 kpa 600 kpa 400 kpa SINGLE TYRE LOAD (kn) FIGURE 26d Maximum vertical stress vs tyre load

36 VERTICAL CONTACT STRESS (kpa) TYRE TYPE V (425/65 R WIDE BASE) Inflation Pressure: 1200 kpa 1000 kpa 800 kpa 600 kpa 400 kpa ICAP SINGLE TYRE LOAD (kn) FIGURE 27a Maximum vertical stress vs tyre load

37 VERTICAL CONTACT STRESS (kpa) TYRE TYPE VI (425/65 R R160AZ WIDE BASE) ICAP 97 Inflation Pressure: 1200 kpa 1000 kpa 800 kpa 600 kpa 400 kpa SINGLE TYRE LOAD (kn) FIGURE 27b Maximum vertical stress vs tyre load

38 VERTICAL CONTACT STRESS (kpa) TYRE TYPE VII (425/65 R R160BZ - WIDE BASE) Inflation Pressure: 1200 kpa 1000 kpa ICAP kpa 600 kpa 400 kpa SINGLE TYRE LOAD (kn) FIGURE 27c Maximum vertical stress vs tyre load

39 ICAP 97 DEPTH (mm) ASPHALT STABILIZED LAYERS SELECTED LAYER RIVER SAND LAYER IN SITU FERRICRETE FIGURE: 28 Pavement structures evaluated with the HVS

40 Radial Distance (mm) ICAP Non-Uniform Vertical Stress Depth (mm) 0 40 Tyre Edge Lateral stress CL FIGURE: 29 Axi-symmetrical Finite Element Model used in this study

41 TYPE I CL 520 kpa (Vertical) ICAP 97 II 520 kpa (Vertical) III 520 kpa (Vertical) IV 520 kpa (Vertical) 260 kpa (Inward Shear) V 520 kpa (Vertical) 260 kpa (Outward Shear) FIGURE: 30 Load/Contact Stress Idealizations used for the analysis in this study

42 LC ICAP 97 Rib 3 Rib 1 Rib 2 Rib 4 Rib 5 TYPE VI - TYRE CENTRE (Vertical and lateral) Rib 1 Rib 2 Rib 3 Rib 4 Rib 5 TYPE VII - TYRE EDGE (Vertical and lateral

43 ICAP 97

44 ICAP 97

45 ICAP 97 Pseudo-Energy under non-uniform contact stress conditions (Symplectic Engineering Corporation, USA)

46 ICAP 97 Colour maps of Shape distortion (Symplectic Engineering Corporation)

47 ICAP 97

48 ICAP 97 VRSPTA Mark III

49 Light Passenger Vehicle: Vertical Contact Stress

50 Light Passenger Vehicle: Lateral Contact Stress

51 Light Passenger Vehicle: Longitudinal Contact Stress

52 ICAP 97

53 ICAP 97

54 ICAP 97

55 Deflectograph Truck (80kN,650 kpa): Vertical Contact Stress

56 Deflectograph Truck (80kN,650 kpa): Lateral Contact Stress

57 Deflectograph Truck (80kN,650 kpa): Longitudinal Contact Stress

58 % Cumulative Frequency 100 DEFLECTOGRAPH (OCTOBER 1998) Test 038-z ICAP kpa (Rear) 600 kpa (Front) 520 kpa (Design) Measured Tire Contact Stress (kpa) Tyre 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

59 ICAP 97 N1 Mantsole Weighbridege

60 ICAP 97

61 Maximum axle load legally allowed on South African Roads from 1996 Type of axle Single axle (steering) Single axle (nonsteering) No of tyres per axle Axle Mass (kg) 2 or (7 700) 76 2 or (7 700) 78 Single axle 4 or more (8 200) 88 Tandem axle 4 or more (16 400) 88 ICAP 97 Load per Axle (kn)* Tridem axle 4 or more (21 000) 78,3 ( ) Previous legal load limits * g = 9,8 m/s 2

62 100 kn Axle WHEEL LOAD 25 kn 25 kn 25 kn 25 kn Road Category [TRH4 (1996)] Percentile Values (%) Contact Stress (kpa) Load Radius (mm) D C B A RECOMMENDED (INTERIM) TYRE CONTACT STRESSES

63 % Cumulative Frequency 100 DEFLECTOGRAPH (OCTOBER 1998) Test 038-z ICAP kpa (Rear) 600 kpa (Front) 520 kpa (Design) Measured Tire Contact Stress (kpa) Tyre 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