Engineering Integrity Society What s that horrible road noise? It s the tyres S d!

Transcription

1 Engineering Integrity Society What s that horrible road noise? It s the tyres S d! 4-5 November 15 NEC, Birmingham

2 Understanding how tire construction affects contact patch acceleration and noise Radiated Noise - 67 pitches 72 pitches 79pitches

3 SPL distribution over the Tyre s Acoustic Cavity 80kph Tyre\level Pitches ( ) /rate 80kph Cavity Mode 1 (235Hz)* rpm Cavity Mode 2 (463Hz)* rpm Cavity Mode 3 (687Hz)* Lin rpm Cavity Mode 4 (921Hz)* rpm Cavity Mode 5 (1148Hz)* rpm Cavity Mode 6 (1386Hz)* rpm (67) (72) (79) *The two rpm s are quoted to emphasise the variability of the tone amplitudes. In general terms at 80kph the 1 st three cavity modes are suppressed by A weighting while the higher modes are amplified. Increasing the significance of the higher modes. 3 23/11/2015 3

4 Correlation exists between the higher levels of internal cavity modes and the total radiated noise (Therefore avoiding strong coupling between the tyres structural and cavity modes makes sense) Light colour CW, Dark colour CCW Reds = (79 pitches) Greens = (72 pitches) Blues = (67 pitches) >80kph The 67 pitch (blue/cyan) is the quietest in the critical 70-90kph region. 4 23/11/2015 4

5 Winter tyre 225/65 R17 1 nylon + 2 steel belts on tread 2 Polyester for sidewall TCM-Microphone Pa TCA-Accelerometer ms -2 RPM 761 = 100kph Modulation of the acoustic cavity modes is high. Contact patch acceleration increases smoothly with speed and shows some modulation. Power up and coast down is at a uniform rate.

6 Overlay of microphone and accelerometer signals highlights the differences Microphone Pa Accelerometer ms -2 The acceleration is peaking at 650 ms -2 and the primary cavity resonance at 300Pa Winter tyre 225/65 R17 1 nylon + 2 steel belts on tread 2 Polyester for sidewall

7 What do these signal sound like? Car winter Tyre (play Noise) 4x4 winter Tyre (Play Noise)

8 Car tyre 205/60R16 1 nylon + 2 steel belts on tread 1 Rayon for sidewall 4x4 Tyre 225/65R17 1 nylon + 2 steel belts on tread 2 Polyester for sidewall

9 4x4 tyre Looking at two full rotations at 101kph Microphone Pa Accelerometer ms -2 At 101kph the contact patch duration and the primary mode period ate equal

10 4x4 tyre Looking at a full rotations at 52kph Microphone Pa Accelerometer ms -2 At 397rpm=52kph The contact patch duration does not map onto the primary cavity resonance Winter tyre 225/65 R17 1 nylon + 2 steel belts on tread 2 Polyester for sidewall

11 Winter tyre 225/65 R17 1 nylon + 2 steel belts on tread 2 Polyester for sidewall Tyre Cavity Microphone Pressure Levels ref 2E -5 Pa

12 Winter tyre 225/65 R17 1 nylon + 2 steel belts on tread 2 Polyester for sidewall Tyre Cavity acceleration levels ref 1 ms -2

13 Winter tyre 225/65 R17 1 nylon + 2 steel belts on tread 2 Polyester for sidewall Radiated noise levels ref 2E -5 Pa

14 4x4 Winter tyre 225/65 R17 1 nylon + 2 steel belts on tread 2 Polyester for sidewall The dips in the wheel rotation order amplitude do correspond with the gaps in the acoustic cavity modes at lower frequencies but not at the higher; is this significant? Mode Hz Dip Hz

15 59.4Hz Tyre and rim in anti-phase

16 105Hz Tyre and rim in torsion anti-phase

17 119Hz

18 1080Hz

19 1620Hz

20 2240Hz

21 Winter tyre 225/65 R17 1 nylon + 2 steel belts on tread 2 Polyester for sidewall Cavity Mic. response Cavity Accel. response

22 Winter tyre 225/65 R17 1 nylon + 2 steel belts on tread 2 Polyester for sidewall Cavity Accel. response Radiated noise ext. mic

23 Comparison of different sidewall construction Radiated noise Both Peaking 5Pa Acceleration Peaking Car 4x ms -2 RPM Profile Peaking Car 4x Winter car 205/60 R16 1 nylon+2 steel; sidewall 1 x Rayon Winter 4x4 225/65 R17 1 nylon+2 steel; sidewall 2x polyester

24 Superposition of acceleration data Winter car Winter 4x4

25 Coasting down approximately 65kph Winter car 576rpm Winter 4x4 528rpm

26 Coasting down at approximately 70kph Winter car 618rpm Winter 4x4 576rpm

27 Coasting down approximately 80kph Winter car 674rpm Winter 4x4 618rpm

28 Coasting down approximately 90kph Winter car 784rpm Winter 4x4 716rpm

29 Zooming in at approximately 90kph Winter car 784rpm Winter 4x4 716rpm

30 Powered at 100kph Winter car 831rpm Winter 4x4 The 4x4 tyre peak acceleration is 50% of the car tyre. The post contact patch wave is also at least 50% lower as well;. This wave is almost certainly driven by the tread blocks releasing from the contact patch.

31 Superposing the summer tyre centre tread and shoulder rib =Centre Tread = Shoulder Rib = Winter 4x4 = Winter car At approx. 85kph

32 Temperature degrees C Deflection = Energy Dissipation* We are interested in the heat generated as the tyre rolls. Using infra red technology the inner surface of the tyre can be scanned and the temperature transmitted. Time in 10 second blocks over a total of 15 minutes *Not in a perfect elastomer but tyres are not perfect elastomers

33 Thank you for listening - Questions please Contact information: Alan Bennetts Tel +44(0) alan@baysystems.ltd.uk Neil Crookes Tel +44(0) NCrookes@coopertire.com

34 Order of Magnitude Calculations They are both large section tyres 60 & 65 % section They were both loaded at standard rig test loads (set for the tyre type) The deflection of the contact patch peak, taken from the accelerometer data, indicates for the car tyre a deflection of order of 14mm and the post contact patch wave amplitude of order 1mm. For the 4x4 tyre the numbers will be around 7mm for the contact patch deflection but the wave deflection will be < 0.1mm Conclusions Keeping the carcass construction the same the amplitude of the waves travelling in the liner and by implication affecting the stability of the tread is affected by an order of magnitude by either or the sidewall tread design or the inflation pressure.

35 Is accelerometer data repeatable? Two coast down runs Separated by 5 minutes. The second run (Green) is slightly higher.

36 The waveforms are identical for the two runs separated by 5 minutes.

37 Future Events EIS 30 th Anniversary Event 6 November 2015, Solihull Introduction to Practical Fatigue Testing 25 November 2015, Instron, High Wycombe Instrumentation, Analysis and Testing Exhibition 15 March 2016, Silverstone 4 th Durability and Fatigue Advances in Wind, Wave and Tidal Energy 28 January 2016, BAWA, Filton Fatigue July 2017, Downing College, Cambridge For further information please contact the EIS Secretariat or visit our website.

38 Contact Website: Tel: +44 (0) Visit us on stand J23