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Mohammad “Mehran” Motamedi, Chuang Su, Michael Craft, Saied Taheri and Corina Sandu

Center for Tire Research (CenTiRe)

Mechanical Engineering Department Virginia Tech

Development of a Laboratory Based

Dynamic Friction Tester

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Content

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• Background/Introduction

• Need and Industrial Relevance

• Objectives

• Computer-Aided Design

• Velocity and Slip Control, and Force Measurement

• Fabricate dominant wavelengths onto disks

• Applications

• Summary

• References

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Background/Introduction

• Friction between tire and road

• Pavement texture – Tire/Road Interactions

• Road Surface Texture Wavelengths:

– Micro-texture

– Macro-texture

• Friction Components:

– Adhesion

– Hysteresis

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Addressing issues faced by tire designers:

Ability to predict the pavement surface characteristics (e.g., rolling resistance, friction and tire wear) as they relate to the tire interaction in terms of the pavement surface features (e.g., texture, roughness).

• Outdoor testing: Weather conditions.

Time -- Money -- Human resources.

• Indoor Testing: Reduced cost

Controlled laboratory environment

Improved data accuracy and reproducibility.

Ease of data accessability and processing

Need and Industrial Relevance

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Objectives

• Develop a laboratory based rubber friction test equipment.

• Investigate frictional effect of texture wavelengths with respect to slip ratio.

• Validate the multi-scale rubber/road contact model using rubber samples from compounds that make up the tire.

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Computer-Aided Design

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Machine Shop Drawings: Dimensions and Tolerances, Material, and Weldments

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Velocity and Slip Control

• AKM42H Sevomotor AKD-P00606 Servodrive VT075-007-0-RM075-40 Gearheard

• AKM44J Sevomotor AKD-P01206 Servodrive VT010-025-0-RM100-40 Gearhead

AKD Drive configuration and programming software.

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Force Measurement and Data Acquisition

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• Spectral Analysis

• Dominant wavelengths onto disks.

• Investigate the contributions of macro- and micro-texture constituents.

• Model the rubber-surface contact and adhesion on multiple scales.

Dominant Wavelengths of Pavement Texture

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Surfaces with decomposed characteristics: Rapid Prototyping

• Methods – Inkjet-based 3D printing systems

– Ridges etched away on silicon wafer

– Selective Laser Sintering

– Stereolithography

• Trade-off – Size, Resolution, Precision and Reliability, Material

Properties, HDT, Cost

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Applications

Multi-Scale Correlations

• Friction stems from the contribution of several scales of macro- and micro-texture. – Measure friction for each scale in the lab.

– Calculate the mean friction for each surface at each scale.

– The friction coefficient of the profile: A linear combination of the scale friction coefficients by scale.

– Maximize the correlation between the measured friction and the calculated friction.

– The scales that account for friction.

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Applications

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Anti-Lock Braking Systems

• Slip Ratio

– Maintained at the tire’s maximum longitudinal force and bounded as close to this region as possible.

• Brake Cylinder Pressure

– Preventing wheel lock • Maximize braking potential

– Minimize stopping distance

– Provide some degree of lateral stability to the vehicle.

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Applications

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Icy Road

• Climate control

– Chamber

– Temperature sensor and humidity sensor

– Control unit

• Sprinkle water to the disk

• Adjust temperature to below zero and generate ice

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Summary

• Need, industrial relevance and objectives

• Design the Dynamic Friction Tester

• Velocity and slip control and force measurement

• Surfaces with desired features

• Applications in ABS braking, test on icy road and multi-scale correlations

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Acknowledgements

Industry Advisory Board of the Center for Tire Research (CenTiRe) for financial support.

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References • American Society for Testing and Materials, “Measuring Surface Friction Properties Using the British

Pendulum Tester,” ASTM Standard Test Method E- 303-93 (2003), Book of ASTM Standards, Volume 04.03, Philadelphia, PA, 2005.

• Bredell, L.J., Johnson, L.B., Kuhlmann-Wilsdorf, Jr. D., “Teaming measurements of the coefficient of friction and of contact resistance as a tool for the investigation of sliding interfaces”, Wear, 120 (1987) 161 – 173.

• American Society for Testing and Materials, “Measuring Pavement Surface Frictional Properties Using the Dynamic Friction Tester,” ASTM Standard Test Method E 1911-98 (2002), Book of ASTM Standards, Volume 04.03, Philadelphia, PA, 2005.

• Berres, R., “High-speed linear friction testing”, Tire Technology International, July 2011, pp. 22-24

• Berritta, R., Cossalter, V., Doria, A., & Ruffo, N. (2002, June). Identification of motorcycle tire properties by means of a testing machine. In Proc. 2002 SEM Annual Conference and Exposition on Experimental and Applied Mechanics (pp. 116-119).

• American Society for Testing and Materials, “Skid Resistant of Paved Surfaces Using a Full-Scale Tire,” ASTM Standard Test Method E 274-97, Book of ASTM Standards, Volume 04.03, Philadelphia, PA, 2005.

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Thank you

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