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The present ratio of test procedures between road and dynamometer measurements is discussed, with reference to a new generation of brake test and measurement equipment. The new concept regards both dynamometer and road testing as one integrated unit. The full capability of recently developed inertia dynamometers can only be exploited through the use of in-vehicle data recorded by a new data acquisition system. An unique insight into brake comfort problems is gained by the use of new opto-electronic measurement procedures in combination with dynamometer testing, e. g. image derotation and thermal imaging.

The complexity of brake NVH work is analyzed, demonstrating that current approaches and problem solving strategies are inadequate. A survey is given of existing NVH test procedures. State of the art, respectively advanced NVH tools are described. The idea of an “Integrated Development & Test Concept” is presented as a vision for future development and test work. Part of it is the new concept of an “Integrated NVH Diagnostic and Problem Solving System”

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 ISO TC22/SWG2 - Brake Lining Committee established a task force to determine and analyze root causes for variability during dynamometer brake performance testing. SAE paper 2010-01-1697 “Brake Dynamometer Test Variability - Analysis of Root Causes” [1] presents the findings from the phases 1 and 2 of the “Test Variability Project.” The task force was created to address the issue of test variability and to establish possible ways to improve test-to-test and lab-to-lab correlation. This paper presents the findings from phase 3 of this effort-description of factors influencing test variability based on DOE study. This phase concentrated on both qualitative and quantitative description of the factors influencing friction coefficient measurements during dynamometer testing.

Brake noise dynamometers are fundamental engineering tools for the systematic and efficient investigations of noise. However, the data obtained from a dynamometer must correlate with the noise achievable on a corresponding vehicle to be of true value in an investigation. The factors that can influence correlation between both vehicle and dynamometer tests are examined. In particular, correlation based on the following: techniques for noise data acquisition, evaluation and testing variations of the brake system under load and time such as aging and wear effects differences in the test procedure brake application parameters variability of individual brake system components in terms of technical release and part-to-part variation. Problems and approaches for correlating dynamometer and vehicle brake test results are described. Test results for the correlation dynamometer - vehicle are also shown.

The efforts of the ISO “Test Variability Task Force” have been aimed at improving the understanding and at reducing brake dynamometer test variability during performance testing. In addition, dynamometer test results have been compared and correlated to vehicle testing. Even though there is already a vast amount of anecdotal evidence confirming the fact that different procedures generate different friction coefficients on the same brake corner, the availability of supporting data to the industry has been elusive up to this point. To overcome this issue, this paper focuses on assessing friction levels, friction coefficient sensitivity, and repeatability under ECE, GB, ISO, JASO, and SAE laboratory friction evaluation tests.