BRRC Belgium abergiersbrrcbe Luc Goubert BRRC Belgium lgoubertbrrcbe Cedric Vuye Artesis Belgium cedricvuyeartesisbe Overview 1 Introduction 2 Trailer measurements 3 Coast down measur ID: 854828
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1 Anneleen Bergiers BRRC, Belgium a.be
Anneleen Bergiers BRRC, Belgium a.bergiers@brrc.be Luc Goubert BRRC, Belgium l.goubert@brrc.be Cedric Vuye Artesis , Belgium cedric.vuye@artesis.be Overview 1. Introduction 2. Trailer measurements 3. Coast down measurements 4. One - third - octave band texture levels 5. Conclusions 2 Overview 1. Introduction 2. Trailer mea
2 surements 3. Coast down measurements
surements 3. Coast down measurements 4. One - third - octave band texture levels 5. Conclusions 3 1 . Introduction Rolling resistance (RR) Energy consumption CO 2 emission Influence of road surface? Rolling Resistance Coefficient: dimensionless ratio of RR force to wheel load C r = F r / F z where the forces F r
3 and F z are magnitudes and not vecto
and F z are magnitudes and not vectors 4 1 . Introduction Trailer measurements ⢠Quarter - car with car suspension ⢠Tyre load 2000 N ⢠Force R counteracting rolling of wheel causes backward motion over angle θ ⢠Sensors: ⢠Inclination θ wheel carrier - frame trailer ⢠Inclination μ frame tra
4 iler - horizontal plane ⢠Incli
iler - horizontal plane ⢠Inclination α trailer - towing vehicle static condition ⢠Tyre temperature: external infrared sensor at sidewall near shoulder tyre ⢠Speed ⢠Acceleration 5 1 . Introduction Coast down measurements ⢠R udimentary measurements ⢠No specialized measuring equipment ⢠Each vehicle was c
5 oasted with transmission disengaged un
oasted with transmission disengaged until standstill ⢠D istance travelled was measured ⢠A lot of parameters are still influencing the measurements: e.g. vehicle RR and aerodynamical resistance 6 1 . Introduction Texture measurements Dynamic laser profilometer BRRC: ⢠78 kHz sample frequency ⢠laser beam 0.2 mm diameter
6 ⢠40 km/h when measuring in steps of
⢠40 km/h when measuring in steps of 0.2 mm ⢠vertical measuring range 64 mm ⢠16 - bit system ⢠vertical resolution 1 μm 7 Overview 1. Introduction 2. Trailer measurements 3. Coast down measurements 4. One - third - octave band texture levels 5. Conclusions 8 2. Trailer measurements Short time repeatability
7 ⢠9 test tracks ⢠5 days in betwee
⢠9 test tracks ⢠5 days in between ⢠Temperature correction: C r (T) = C r (T 0 ) * e ( (T 0 - T) / T 1 ) where T 0 = 30 ° C, T 1 = 50 ° C [ Descornet ] ⢠All outliers were included in graphs and analyses ⢠Good repeatability (slope approaches 1) ⢠Reasonable correlation 9 2. Trailer measurements L
8 ong time repeatability ⢠Part I:
ong time repeatability ⢠Part I: ⢠2 measurement campaigns ⢠10 test sections ⢠2 different groups of researchers ⢠8 â 11 months ⢠Good repeatability (slope approaches 1) ⢠Correlation not so good ⢠Possible reasons: ⢠2 different groups of researchers, communication errors ⢠Wear road surface ⢠Calibration e
9 rrors students 10 2. Trailer m
rrors students 10 2. Trailer measurements Long time repeatability ⢠Part II: ⢠2 measurement campaigns ⢠other test sections (same as short term repeatability) ⢠same group of researchers ⢠3 months ⢠Repeatability is good (slope of approaches 1) ⢠Correlation is reasonable 11 2. Trailer measurements
10 Tyre load ⢠loads : 1285 N, 1416 N,
Tyre load ⢠loads : 1285 N, 1416 N, 1547 N, 1678 N, 1809 N and 1939 N ⢠2 directions of street : east and west ⢠influence load on RR force is linear ⢠C r constant and more or less independent of the load ⢠applying temperature correction yields better correlation 12 2. Trailer measurements Tyre inflation pr
11 essure ⢠1.2 bar - 3.2 bar (in
essure ⢠1.2 bar - 3.2 bar (in steps of 0.5 bar) ⢠tyre inflation pressure decrease = C r increase ⢠1 bar difference = approx. 0.004 raising or lowering of C r (15 - 20 %) ⢠tyre inflation pressure very important factor for RR ⢠tyre inflation pressure increases with temperature - � good warm - up proc
12 edure 13 2. Trailer measurements
edure 13 2. Trailer measurements Wind shielding ⢠removable wooden windscreen ⢠measurements with old and new tyre at 30 , 50 and 70 km/h ⢠eastern wind during measurements with new tyre ⢠generally C r higher without windscreen ⢠windscreen absolutely necessary for measurements , but windscreen all around tyre and
13 to ground level would even be better
to ground level would even be better -40.00% -20.00% 0.00% 20.00% 40.00% 60.00% 80.00% 30 50 70 30 50 70 30 50 70 30 50 70 east west east west new tyre old tyre Relative difference with/without windscreen Speed [km/h] 14 2. Trailer measurements Speed ⢠measurements with old and new tyre at 30 , 50 and 70 km/h with/without windscr
14 een ⢠generally C r increases whe
een ⢠generally C r increases when speed increases (except for one measurement without windscreen) ⢠m ore recent research [MIRIAM]: larger windscreen (encapsulating whole tyre) advisable to eliminate wind influence at higher speed 0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0 20 40 60 80 C r Speed [km/h] New tyre, windscreen
15 W New tyre, windscreen E New tyre, witho
W New tyre, windscreen E New tyre, without windscreen W New tyre, without windscreen E Old tyre, windscreen W Old tyre, windscreen E Old tyre, without windscreen W Old tyre, without windscreen E 15 2. Trailer measurements Tyre type ⢠old tyre: slick Michelin SB - 15/63 - 14X, about 30 years old ⢠new tyre: Michelin Energy Saver 195/70 R14 9
16 1T ⢠C r values new tyre lower
1T ⢠C r values new tyre lower than old tyre ⢠not only road surface important share on RR, also tyre ⢠well thought selection of tyre can provide lower CO2 emission old tyre new tyre 16 Overview 1. Introduction 2. Trailer measurements 3. Coast down measurements 4. One - third - octave band texture levels 5. Conclusio
17 ns 17 3. Coast down measurements
ns 17 3. Coast down measurements ⢠Always same driver, fuel tank filled up before start ⢠Tyre pressure â cold condition ⢠A t least 10 km to warm up tyres ⢠Length test sections 100 to 200 m ⢠I nitial speed 20 km/h vehicle A and 25 km/h vehicle B ⢠Clutch pedal pushed, coasted from start point until
18 standstill, distance measured ⢠To
standstill, distance measured ⢠To eliminate influence slope , measurements in 2 directions � because of safety on opposite driving lane ⢠3 coast down measurements in each direction ⢠Dry weather conditions and low wind ⢠Ambient air temperature: 5.6 - 20.5 ° C � no temperature corrections 18 3. Coast down
19 measurements Vehicle A Vehi
measurements Vehicle A Vehicle B Vehicle type Audi A3 S - Line (2003) Peugeot 307 (2005) Vehicle weight (driver included) 1480 kg 1400 kg Picture of vehicle Tyre Inflation 2.5 bar 2.4 bar Tyre type Triangle 225/45ZR17 Michelin 205/55R16 Tread depth tyre 6.0 mm 4.8 mm Picture of tyre 19 3. C
20 oast down measurements y = 0.6077
oast down measurements y = 0.6077x + 105.65 R² = 0.26 y = 2,9911x - 115,44 R² = 0,47 y = - 1,0354x + 268,32 R² = 0,28 0 25 50 75 100 125 150 175 200 225 250 0 25 50 75 100 125 150 175 Distance vehicle B [m] Distance vehicle A [m] Direction 1 Direction 2 Average All sections y = 0,501x + 107,33 R² = 0,42 y = 3,9906x - 197,92 R
21 ² = 0,50 y = - 1,2204x + 275,97 R²
² = 0,50 y = - 1,2204x + 275,97 R² = 0,59 0 25 50 75 100 125 150 175 200 225 250 0 25 50 75 100 125 150 175 Distance vehicle B [m] Distance vehicle A [m] Direction 1 Direction 2 Average Only sections with homogeneous texture in both directions Corrrelation between measurements 2 vehicles 20 3. Coast down measurements Corrrelati
22 on between coast down and trail
on between coast down and trailer measurements y = 268,49x + 87,78 R² = 0,236 y = - 1.299,53x + 191,37 R² = 0,91 0 20 40 60 80 100 120 140 160 180 200 0.00 0.01 0.02 0.03 0.04 0.05 Coast down measurements - Distance [m] Trailer measurements - C r Vehicle A Vehicle B ⢠6 test sections in common ⢠Vehicle B shows good correla
23 tion (25 km/h) ⢠Low correlation veh
tion (25 km/h) ⢠Low correlation vehicle A (20 km/h) ⢠Explanation: ⢠vehicle A less accurate because of lower initial speed? ⢠first measurements, operators not yet used to measurement method? 21 Overview 1. Introduction 2. Trailer measurements 3. Coast down measurements 4. One - third - octave band texture levels 5. Con
24 clusions 22 4. One - third - octave
clusions 22 4. One - third - octave band texture levels Texture measurements (trailer, De Bie â Hofmans) 0 10 20 30 40 50 60 70 Texture level [dB re. 1 µm] Wavelength [m] Heiveldekens K. Astridlaan Lodderstraat Rijksweg Rumstsestraat Scheldeweg Schoonaardestraat Tolhuisstraat Tervurenlaan E Tervurenlaan W 23 4. One - third - octave ban
25 d texture levels Texture measur
d texture levels Texture measurements ( coast down, Aerts â Cools) 0 10 20 30 40 50 60 70 Texture level [dB re. 1 µm] Wavelength [m] Hooiendonkstraat Nekkerhal 1 Nekkerhal 2 Nekkerhal 3 Roekstraat Steenweg op Heindonk Corluylei Prinsendreef Stijn Streuvelslaan Van Den Nestelaan 24 4. One - third - octave band texture levels 0.000
26 0.100 0.200 0.300 0.400 0.500 0.600 0.7
0.100 0.200 0.300 0.400 0.500 0.600 0.700 0.800 0.01 0.02 0.04 0.08 0.15873 0.31746 0.5 R² Wavelength [m] R² De Bie- Hofmans R² Descornet R² Dotsenko- Helsen R² Aerts-Cools (Vehicle A) R² Aerts-Cools (Vehicle B) ⢠Low correlations De Bie â Hofmans: change of tyre, new sensors⦠calibrations issues ⢠Contact area length of car tyre is
27 0.15 m; maxima graphs Dotsenko - Hel
0.15 m; maxima graphs Dotsenko - Helsen and Aerts - Cools (B) are situated around 0.16 m wavelength 25 Overview 1. Introduction 2. Trailer measurements 3. Coast down measurements 4. One - third - octave band texture levels 5. Conclusions 26 5. Conclusions ⢠Long and short time repeatability reasonable ⢠Influence of lo
28 ad on RR force linear; C r constant
ad on RR force linear; C r constant and more or less independent of load ⢠Tyre inflation pressure large influence ; 1 bar difference = approx. 0.004 raising or lowering of C r (15 - 20 %) ⢠Wind shielding necessary - � more accurate results at higher speeds 27 5. Conclusions ⢠C r increases slightly when s
29 peed increases; more research needed
peed increases; more research needed larger windscreen ⢠Selection of tyre â lower CO 2 emission ⢠Calibration very delicate, high influence ⢠Rudimentary coast down plausible RR results ⢠Very good correlations RR â megatexture (coast down, Dotsenko - Helsen , Descornet ) 28 Thank you for your attention!