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

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Presentation on theme: "Development of Refined Friction Materials Dr. Tim Hodges NVH Manager Federal-Mogul Friction Products Group."— 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 Friction Material (“Excitation”) Brake System (“Response”) Finite Element Modelling Measurement of System on Noise Dynamometer and/or Vehicle Scanning Laser Vibrometer Accelerometer Data Acquisition (LMS) Noise vs Formulation (FMTL + Dev’t Centres) Noise Measurement on Dynamometer c/w knuckle or full suspension Core Development Application Engineering

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

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 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 Temp (C)

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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