1 / 18

Experimental and Computational Studies of Contact Mechanics for Tire Longitudinal Response

Experimental and Computational Studies of Contact Mechanics for Tire Longitudinal Response. Jacob Kidney, Neel Mani, Vladimir Roth, John Turner, & Tom Branca Bridgestone Americas Tire Operations Product Development Group Akron, OH . 30 th Tire Society Conference Akron, Ohio

hovan
Download Presentation

Experimental and Computational Studies of Contact Mechanics for Tire Longitudinal Response

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Experimental and Computational Studies of Contact Mechanics for Tire Longitudinal Response Jacob Kidney, Neel Mani, Vladimir Roth, John Turner, & Tom Branca Bridgestone Americas Tire Operations Product Development Group Akron, OH 30th Tire Society Conference Akron, Ohio September 14, 2011

  2. Motivation for Interest in Dry Braking Performance • OEM’s are requiring improved Stopping Distance performance • ABS systems are now standard safety features, and the potential for improvement is enhanced • European & Asian countries have active NCAP programs to Test & Improve Dry Stopping Distance for Safety • Consumers Union & IIHS generate and publish U.S. vehicle ratings and include Stopping Distance as a measure of Safety • SAE Committee has developed a standardized stopping distance test procedure

  3. Tread Belt Belt Tread z Ω VBelt x Vbelt VGround Shear zx(Vg /Vb) GROUND Vground Drive Free Rolling Brake Drive-Brake Force Generation & Slip Zone Evolution 1D Concept “Brush” Model Friction limit =  Drive Drive Drive Free Rolling Slip Zone Evolution Shear Stress Shear Stress Brake Brake Brake Friction limit =  • Vg/Vb is the Basic Mechanism of Tread Shear Development • Tread Shears until it Reaches Friction Limit • Slip Zones Evolve from the Rear of Footprint

  4. Contact Behavior – Free-Rolling & Braking Conditions Free Rolling Moderate Braking (SR=6%)

  5. FREE ROLLING Slip Zone Evolution & Mu-Slip Curve - Brush Model 0 Driving STICK SLIP STICK SLIP STICK SLIP Braking 0 FREE ROLLING INCREASING BRAKE TORQUE Concept Model 0 0/σ0 Driving Increasing Free Rolling Torque Ramp Braking 0/0 Stress Shape Controlled by Slip Zone Evolution 0 Slip Rate at Peak is Altered as well Shape of the mu-Slip Curve is Affected by Slip Zone Evolution (Rate of Fx generation diminishes as Slip Zone Increases)

  6. Slip Zone Growth – Effects on µ-Slip Shape Experimental Measurement FEA Prediction µ vs Slip Rate µ vs Slip Rate 1.2 1.2 1.0 Drive Torque 1.0 Drive Torque 0.8 0.8 0.6 0.6 0.4 0.4 Brake Torque re-plotted in Drive Quadrant Brake Torque re-plotted in Drive Quadrant 0.2 0.2 µ (Fx/Fz) µ (Fx/Fz) 0 0 -0.2 -0.2 -0.4 -0.4 Brake Torque -0.6 -0.6 -0.8 -0.8 Brake Torque -1.0 -1.0 -1.2 -1.2 -15.0 -12.5 -10.0 -7.5 -5.0 -2.5 0 2.5 5.0 7.5 10.0 12.5 15.0 -15.0 -12.5 -10.0 -7.5 -5.0 -2.5 0 2.5 5.0 7.5 10.0 12.5 15.0 Slip Rate (%) Slip Rate (%) Rolling Tire Simulator SST Braking & Cornering

  7. zx/zz Brake Torque - FEA Drive Torque - FEA SLIP Example of Contrasting Slip Zone Growth Rates Experimental Measurement FEA Prediction Travel TRAILING EDGE LEADING EDGE SLIP ZONE ZONE Brake Torque – Concept Model INCREASING TORQUE zx/zz SLIP STICK STICK SLIP STICK SLIP SLIP ZONE Drive Torque – Concept Model • Drive & Brake mu-Slip Curves Differ due to Slip Zone Evolution

  8. Slip Zone Evolution for All-Season Tire Under Braking FRONT REAR Rolling Direction Slip Zone Growth zz LOW HIGH SR = 0% SR = 2% SR = 4% SR = 6% SR = 8%

  9. Fundamental Studies of Lift-Off Increased Braking Free Rolling Heavy Braking Medium Braking “Summer” Contrasting Lift-Off “All Season” “Winter”

  10. Coef. of Friction Contact Pressure Friction – Impact of Pressure Dependence Free-Rolling Braking Lug Lift Z Lug LIFT-OFF WHEN Z=0 Braking Shear Lug Lift-Off Reduces Contact Area and Increases Dry Stopping Distance. WHY?? Coef. of Friction is Pressure Sensitive 140 250 375 280 500 420 Pressure (kPa) 625 Velocity (mm/sec) 560 750 700 Reduced Area Increased z Reduced COF Increased DSD

  11. Impact of Friction Law on Braking Performance Sliding Direction Apply Load Un-Deformed Lug Mu vs Distance – Comparison between Friction Laws Constant COF 18% Decrease Mu (Fx/Fz) COF Variable COF Pressure Distance

  12. Impact of Sipes on Braking Performance Mu vs Distance – Siping Impact Solid Lug 19% Decrease Mu (Fx/Fz) 2-Sipe Lug Solid Lug Contact Pressure (kPa) - 1900 - 330 - 300 - 270 - 240 - 210 - 180 - 150 - 120 - 90 - 60 - 30 - 0 2-Sipe Lug 2-Sipe Lug Distance Lug Sliding (Mesh) Contact Pressure while Sliding Lift-Off Zones Lift-Off Zone Solid Lug 2-Sipe Lug Solid Lug 2-Sipe Lug

  13. Impact of Contact Stress on Braking Performance Mu vs Distance – Impact of Contact Stress 6% Drop 6% Drop Mu drops with increased Fz Mu (Fx/Fz) Fz = 225 N Fz = 300 N Fz = 375 N Distance Fz = 225 N Fz = 300 N Fz = 375 N Contact Pressure (kPa) Increased Pressure @ Leading Edge Moderate Pressure @ Leading Edge Very High Pressure @ Leading Edge - 360 - 330 - 300 - 270 - 240 - 210 - 180 - 150 - 120 - 90 - 60 - 30 - 0

  14. Implications for ABS Braking Performance 46.0 45.7 Stopping Distance Performance 45.4 45.1 44.8 44.5 DSD (m) 44.2 43.9 43.6 43.3 43.0 42.7 52.1 51.8 51.5 51.2 50.9 • If several different tire sets are tested on multiple vehicles, Stopping Distance rank order will likely change. • A tire-vehicle interaction is involved that influences performance. 50.6 DSD (m) 50.3 50.0 49.7 49.4 49.1 48.8

  15. Implications for ABS Braking Performance Mu-Slip Curves for Various Tires Stopping Distance for Various Tires Tire A Tire B Tire C Mu (Fx/Fz) Stopping Distance Tire A Tire B Tire C Slip Rate Tire Slip Rate vs Time SR Cycling with Phase Lag LF SR RF SR Fz5 Fz4 Fz3 Fz2 Mu (Fx/Fz) Slip Rate Fz1 Tire Mu-Slip Curves & ABS Cycling Slip Rate Time (sec)

  16. Implications for ABS Braking Performance Mu-Slip Curves for Various Tires • Peak Is Constant • Slope & Curvature Varied • CONSIDER A “SLIP RATE-BASED” ABS CONTROLLER Mu (Fx/Fz) ABS Operating Range (SR-Based ABS Controller) Tire A Tire B Tire C 0% 2% 4% 6% 8% 10% 12% 14% 16% 18% 20% 22% 24% 26% Slip Rate

  17. Implications for ABS Braking Performance Mu-Slip Curves for Various Tires • Peak Is Constant • Slope & Curvature Varied • CONSIDER A “SLIP RATE-BASED” ABS CONTROLLER ABS Operating Efficiency is Influenced by the Shape of the mu-Slip Curve Mu (Fx/Fz) ABS Operating Range (SR-Based ABS Controller) Tire A Tire B Tire C 0% 2% 4% 6% 8% 10% 12% 14% 16% 18% 20% 22% 24% 26% Slip Rate

  18. Implications for ABS Braking Performance Base Mu-Slip Curves for Different Tires Tire A • Peak Is Constant • Slope & Curvature Varied • CONSIDER A “PEAK-SEEKING” ABS CONTROLLER Tire B Mu (Fx/Fz) ABS Operating Efficiency is Influenced by the Shape of the mu-Slip Curve Slip Rate Mu-Slip Curves for Different Tires Mu-Slip Behavior for Different Tires during an ABS Simulation Steady ABS Operation Transient Tire A Tire B Braking Force, Fx Braking Force, Fx Penalty for Excessive Pressure Release PERFORMANCE LOSS BETTER PERFORMANCE Tire A Tire B Slip Rate Time

More Related