Runflat tire and it s impact on BiAx Testing

Transcription

1 13 th Users Conference on BiAxial Fatigue Testing November 08 th, 2017 Runflat tire and it s impact on BiAx Testing Dipl. Ing. Said Allouch Fraunhofer-Institut für Betriebsfestigkeit und Systemzuverlässigkeit LBF

2 Relevance of tires With regard to vehicle dynamics the tire is the basic load transfer element The usage of the tire in the biax testing make this technology near to the reality development in the field of tire technology do show a clear trend towards runflat Runflat different build up different behavior regarding the durability Page 2

3 Possible impacts of Tires Test External wheel loads on the road Internal wheel stresses on the road/lbf flat track Internal wheel stresses during testing Page 3

4 Differences of physical characteristics Run Flat vs. Standard Tire vertical stiffness The vertical stiffness of run flat tires is 33% higher than the stiffness of standard tires The lower the vertical stiffness of a tire, the lower the occurring vertical loads Jeschor, M.: Ein neues Verfahren zur Bewertung von Runflat-Reifen ein Beitrag auf dem Weg zum reserveradlosen PKW; Diss. TU Dresden, 2005 Page 4

5 Differences of physical characteristics Run Flat vs. Standard Tire lateral stiffness The lateral stiffness of run flat tires is higher than the lateral stiffness of standard tires which cause better handling properties This difference has also an effect on the external loads and the transmission of the loads into the wheel Jeschor, M.: Ein neues Verfahren zur Bewertung von Runflat-Reifen ein Beitrag auf dem Weg zum reserveradlosen PKW; Diss. TU Dresden, 2005 Page 5

6 Chosen tires of the investigation tire Bridgestone Turanza Bridgestone Turanza MOE abbreviation MOE Bridgestone Turanza RFT Michelin Primacy 3 ZP RFT MP Tire size 225/45 R17 Wheel size 7.0 x 17 Page 6

7 Impact on external loads Used test vehicle Opel Astra J 103 kw Tire size 225/45 R17 Wheel size 7.0 x 17 Static load = 500 kg 7x17 RoaDynET = 66,4mm Lochkreis: 5x112 Zentrierung: 57 mm Radbolzen M14x1,5 mit 90 Kegel Max. Länge ab Konus Beginn 53mm Min. Länge ab Konus Beginn 40mm Beste Länge ab Konus 45-50mm Bereifung: 215/50 R17 Page 7

8 Impact on external loads Measurement tracks (Dudenhofen) Durability Cornering Rough road Page 8

9 Impact on external loads Tire positions during RLDA MOE A RFT MP MOE MP B RFT MP RFT C MOE RFT D MP MOE 4 different wheel positions were measured with the same tire and manoever the wheels swaped places in clockwise rotation Air pressure of all tires: 2,7 bar Tire temperature: comparable on each measurement Bolting torque (wheel bolt) : 120 Nm Page 9

10 Impact on external loads Tire positions during RLDA MOE A RFT MP MOE MP B RFT MP RFT C MOE RFT D MP MOE Page 10

11 Fh [kn] Fv [kn] Impact on external loads Results (rough road) 150% 130% 100% 50% 125% 120% 115% 0% -50% 110% 105% 100% -100% 95% -150% -200% MOE RFT MP 90% 85% 80% MOE RFT MP Page 11

12 Fh [kn] Fv [kn] Impact on external loads Results (cornering) 110% 140% 105% 130% 100% 120% 95% 110% 90% 100% 85% 90% 80% MOE RFT MP 80% MOE RFT MP Page 12

13 Lateral force [kn] Impact on external loads Results (lateral forces spectra comparison) Range pair Page 13

14 Vertical force [kn] Impact on external loads Results (vertical forces spectra comparison) Range pair Page 14

15 Impact of the runflat tire on the internal stresses LBF Flat track roll rig Fv [kn] Fh [kn] Static load 5,0 0 Straight driving incl. rough road 13,90 +/-3,50 Cornering 9,04 6,66 Page 15

16 Amplitude [MPa] Amplitude [MPa] Amplitude [MPa] Impact of the runflat tire on the internal stresses Results I inner rim flange 17% 13% inner spoke transition to the rim 18% 14% under static load straight driving cornering 0 under static load straight driving cornering % 10% under static load straight driving cornering inner mid of spoke Page 16

17 Amplitude [MPa] Amplitude [MPa] Amplitude [MPa] Impact of the runflat tire on the internal stresses Results II inner spoke transition to the bolting area under static load straight driving cornering % 7% outer rim flange 17% under static load straight driving cornering 5 0 bolting area under static load straight driving cornering 21% 7% Page 17

18 Impact of the runflat tire on the internal stresses LBF ZWARP machine Load file: LBF standard Tire inflation pressure: 4 MPa Measurement of 1 loop -> extrapolation to 10,000 km Page 18

19 normalized RFS values Impact of the runflat tire on the internal stresses RFS results 110% RFS values comparison 105% 100% 95% 90% MOE RFT MP 85% 80% inner rim flange inner spoke transition to the rim inner mid of spoke inner spoke transition to the bolting area bolting area outer rim flange Page 19

20 Conclusions All parts of the process chain were investigated External loads: Runflat tires have an impact on lateral and horizontal wheel loads -> RLDA needs to be performed with RFT Internal stresses (LBF flat track roll rig): Runflat tires cause higher internal stresses by straight -> ESA needs to be performed with RFT Internal stresses (LBF ZWARP): Runflat tires cause small impact on local stresses -> Test is recommended to be performed with RFT Different RFT were investigated, they performed different, a general impact was not given Page 20

21 Contact Fraunhofer Institute for Structural Durability and System Reliability LBF Group Validation Wheel Related Components Bartningstrasse 47, Darmstadt, Germany Telefon: , Fax: Said Allouch Application specialist passenger cars Page 21