This content is not included in your SAE MOBILUS subscription, or you are not logged in.
Brake Dynamometer Test Variability - Analysis of Root Causes
ISSN: 0148-7191, e-ISSN: 2688-3627
Published October 10, 2010 by SAE International in United States
This content contains downloadable datasetsAnnotation ability available
Modern project management including brake testing includes the exchange of reliable results from different sources and different locations. The ISO TC22/SWG2-Brake Lining Committee established a task force led by Ford Motor Co. to determine and analyze root causes for variability during dynamometer brake performance testing. The overall goal was to provide guidelines on how to reduce variability and how to improve correlation between dynamometer and vehicle test results. This collaborative accuracy study used the ISO 26867 Friction behavior assessment for automotive brake systems. Future efforts of the ISO task force will address NVH and vehicle-level tests.
This paper corresponds to the first two phases of the project regarding performance brake dynamometer testing and presents results, findings and conclusions regarding repeatability (within-lab) and reproducibility (between-labs) from different laboratories and different brake dynamometers. The new EKB 3008 data exchange format was used by participating facilities to share test results using spreadsheet applications, help automate the evaluations, and simplify the different comparisons performed for this project. This on one of the first practical applications for the EKB 3008 format with several software platforms involved.
In order to minimize variations caused by test parts, components (brake discs, brake pads, calipers and vehicle knuckles) were carefully selected, prepared, and measured prior to testing. Special attention was given to: test procedure implementation, critical braking and testing conditions, dynamometer setup and controls, data collection, data processing and test evaluation routines. Statistical analysis (Minitab® and ISO Statistical Methods) were used to separate variability caused by test parts and caused by the test setup. Based on the findings, the paper presents guidelines for improving repeatability (within-lab) and reproducibility (between-labs) during regular testing activities.
Compared to vehicle testing, variability root-cause investigation using brake dynamometers is more efficient (less sources of variation and less use of testing and engineering resources) and under more controlled conditions. Findings from this variability study will support future improvement efforts for several laboratory and vehicle performance and NVH test procedure and techniques.
|Journal Article||Brake Dynamometer Test Variability Part 2- Description of the Influencing Factors|
|Ground Vehicle Standard||Air Brake Actuator Test Performance Requirements - Truck and Bus|
|Ground Vehicle Standard||Air Brake Actuator Test Procedure, Truck-Tractor, Bus, and Trailers|
CitationGrochowicz, J., Wollenweber, K., Agudelo, C., and Abendroth, H., "Brake Dynamometer Test Variability - Analysis of Root Causes," SAE Technical Paper 2010-01-1697, 2010, https://doi.org/10.4271/2010-01-1697.
Data Sets - Support Documents
|[Unnamed Dataset 1]|
- ISO International Standard, “Road vehicles-Brake lining friction materials-Friction behavior assessment for automotive brake systems,” ISO 26867:2009.
- Abendroth, H., Haverkamp, M., Hoffrichter, W., Blaschke, P. et al, “Current and New Approaches for Brake Noise Evaluation and Rating,” SAE Int. J. Passeng. Cars - Mech. Syst. 2(2):32-45, 2009, doi:10.4271/2009-01-3037.
- Bender, A., Haesler, K., Thomas, C., and Grochowicz, J., “Development of Universal Brake Test Data Exchange Format and Evaluation Format,” SAE Technical Paper 2010-01-1698, 2010, doi:10.4271/2010-01-1698.
- Minitab Inc., Minitab (Version 15), Statistical Software, State College, PA, 2007.
- Dohle, A., Elvenkemper, A., Lange, J., and Degenstein, T., “The µ Value”-Friction Level Determination in Brake Systems,” XXVI International µ-Symposium. Fortschritt-Berichte VDI Nr. 620.
- Dohle, A. and Fritzen, C-P., “Investigation of model based friction coefficient measurement (part I),” Institution of Mechanical Engineers Braking 2009, CHANDOS PUBLISHING, 2009.
- ISO International Standard, “Road vehicles-Brake lining-Compressive strain test method,” ISO 6310:2009.
- ISO International Standard, “Accuracy (trueness and precision) of measurement methods and results-Part 1: General principles and definitions,” ISO 5725-1:1994
- Schmitt, O. and Duncan, T., “Method for Extracting Full Spectrum of Friction Materials Performance (Fingerprinting) using the SAE J2681,” SAE Technical Paper 2004-01-2768, 2004, doi:10.4271/2004-01-2768.
- SAE International Surface Vehicle Recommended Practice, “Dynamometer Global Brake Effectiveness,” SAE Standard J2522, Issued Jun. 2003.
- SAE International Surface Vehicle Recommended Practice, “Disc and Drum Brake Dynamometer Squeal Noise Matrix,” SAE Standard J2521, Rev. Jan. 2006.
- ISO International Standard, “Road vehicles-Brake lining friction materials-Product definition and quality assurance,” ISO 15484:2008
- ISO International Standard, “Accuracy (trueness and precision) of measurement methods and results-Part 2: Basic method for the determination of repeatability and reproducibility of a standard measurement method,” ISO 5725-2:1994
- ISO International Standard, “Accuracy (trueness and precision) of measurement methods and results-Part 6: Use in practice of accuracy values,” ISO 5725-6:1994
- ISO International Standard, “Accuracy (trueness and precision) of measurement methods and results -- Part 5: Alternative methods for the determination of the precision of a standard measurement method,” ISO 5725-5:1998
- JCGM Joint Committee for Guides in Metrology, “Evaluation of measurement data-An introduction to the “Guide to the expression of uncertainty in measurement” and related documents,” JCGM 104:2009
- Degenstein, T. and Winner, H. “New methods of force and temperature measurement on a wheel brake during the braking process,” XXVII International µ-Symposium. Fortschritt-Berichte VDI Nr. 657.
- Fieldhouse, D. and Ashraf, N. “Observation of the disc/pad interface pressure distribution during variable braking conditions and its influence on brake noise,” XXVII International µ-Symposium. Fortschritt-Berichte VDI Nr. 657.
- Sanders, P.G., Dalka, T., and Hartsock, D., “Friction Material Compressibility as a Function of Pressure, Temperature, and Frequency,” SAE Technical Paper 2008-01-2574, 2008, doi:10.4271/2008-01-2574.
- Tekscan, Inc., I-Scan® Pressure Measurement System, South Boston, MA, 2008.
- Yuan, Y. and Halloran, P., “Calculation of Average Coefficient of Friction During Braking,” SAE Technical Paper 1999-01-3410.
- Sardá, A., Haag, M., Winner, H., and Semsch, M., “Experimental Investigation of Hot Spots and Thermal Judder,” SAE Technical Paper 2008-01-2544.
- Eisengräber, R., Grochowicz, J., Schuster, M., Augsburg, K. et al., “Comparison of Different Methods for the Determination of the Friction Temperature of Disc Brakes,” SAE Technical Paper 1999-01-0138, 1999, doi:10.4271/1999-01-0138.
- Dada, A.R., “Hayes High Airflow Design Rotor for Improved Thermal Cooling and Coning,” SAE Technical Paper 982248, 1998, doi:10.4271/982248.
- Bröring, M., “Evaluation and Simulation of Brake Tests with Implementation on a Brake Dynamometer (Auswertung und Simulation von Bremsentests sowie deren Implementierung auf einem Dynamometer),” Diploma thesis, Cologne, 2009.
- Krishnapur, K. and Luo, J., “Brake Squeal Rig and LACT Vehicle Test Correlation Improvement - Focus on Thermal Conditioning,” SAE Technical Paper 2004-01-2791, 2004, doi:10.4271/2004-01-2791.
- Körner, M., Decker, F., Dreyer, M., and Radespiel, R., “Examination of the brake disc air flow on a wind tunnel model of the VW Phaeton with transparent front wheel,” XXVII International µ-Symposium. Fortschritt-Berichte VDI Nr. 657.
- Schuetz, T., “Cooling Analysis of a Passenger Car Disk Brake,” SAE Technical Paper 2009-01-3049, 2009, doi:10.4271/2009-01-3049.
- Matozo, L.T., Soares, M.R.F., and Al-Qureshi, H.A., “The Effect of Environmental Humidity and Temperature on Friction Level and Squeal Noise Propensity for Disc Brake Friction Materials,” SAE Technical Paper 2008-01-2534, 2008, doi:10.4271/2008-01-2534.
- Evans, C. and O'Rourke, M., “The Effects of Humidity on Friction Material Performance,” presented at SAE 2004 Brake Colloquium & Exhibition, USA, October 10-13, 2004.
- SAE International Surface Vehicle Standard, “Dynamometer Effectiveness Characterization Test for Passenger Car and Light Truck Brake Friction Products,” J2430, Issued Aug. 1999.