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Development of Refined Friction Materials

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Presentation on theme: "Development of Refined Friction Materials"— Presentation transcript:

1 Development of Refined Friction Materials
Dr. Tim Hodges NVH Manager Federal-Mogul Friction Products Group

2 Overview Key attributes of friction material NVH strategy
Principal NVH concern areas squeal judder creep-groan Summary

3 Friction Materials - Key Criteria
Physical properties compressibility thermal conductivity Performance nominal friction fade speed/temp/pressure sensitivity Wear Cost Environmental Refinement cold/thermal judder creep-groan squeal pedal feel +……………………..

4 Federal-Mogul Approach to NVH
Noise vs Formulation (FMTL + Dev’t Centres) Noise Measurement on Dynamometer c/w knuckle or full suspension Friction Material (“Excitation”) Core Development Finite Element Modelling Application Engineering Measurement of System on Noise Dynamometer and/or Vehicle Scanning Laser Vibrometer Accelerometer Data Acquisition (LMS) Brake System (“Response”)

5 Structured Dev’t of Quiet Materials

6 Noise Dynamometers Must reproduce noise from vehicle testing
Full-suspension capability (front/rear axle) Other key features: Climate control LACT & matrix-type schedules Standard objective assessment methods Low background noise required for accurate assessment Roller on some machines

7 NVH Problem Solving - Example
1.8 kHz noise problem Modal analysis shows component frequencies not related to noise frequency Laser vibrometer, noise dyno & vehicle used to provide solution Laser identifies high vibration levels on leading edge inner pad Solution - move inner pad clip by 1.5 mm Subjective/objective results: mm/s Mod 60 50 40 30 20 10

8 Creep-groan Creep-groan occurs at very low speeds, < 2rpm
Used for core development material screening Very low speed, high torque capability, allows relation of  characteristics to vibration using full-size pads

9 DTV Generation and Cold Judder
DTV generation subject to a wide range of factors (Driving style, Calliper characteristics, Friction material tribology & compressibility) Need to “screen” good/bad materials Key to control of test lies in pad/disc contact In a vehicle contact refreshed with periodic brake app’s Does not guarantee reproducible results even on dynamometer Controlled Contact Device maintains and controls pad/disc contact in ‘off brakes’ situation Compensates for wear Does not require special caliper

10 High Speed (“Hot”) Judder
Temp (C) 700 600 500 400 300 200 Speed (Km/h) Frequency (Hz) DTV measurement systems and the F-M dual wavelength pyrometer may be used together to measure the effects of hot spotting

11 Advanced NVH Modelling
Need to represent system components We have good model-experiment correlation for system level modal analyses We are continuing to develop our analytical modelling methods to give us a predictive capability

12 Summary Performance, refinement, time & cost are often conflicting compromises Structured approach required for problem identification & solution More analytical work required

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