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Methodology to determine the clutch facing sensitivity regarding judder in the vehicle. Vehicle “Judder” is identified as low frequency and high amplitude vibrations that, depending on their intensity, can cause uncomfortable driving. Today the judder test is performed in a sensitive car concerning judder, however it takes long time due to the need of assemble the complete clutch set (disc, clutch cover, flywheel) for each test. Therefore, the aim of this work is to develop a methodology for the classification of facing sensitivity regarding judder. However in subscale bench test, because the idea is not only to reduce test time, but also to speed-up the facing material development. The preliminary results are very promising due to a good correlation between subscale tests and the vehicle.

The necessity to improve the reliability of clutch facing in burst resistance characteristic was checked on a specific part number due to a high customer specification for burst resistance. It was decided to use multivariable analyses tools such as Tree Clustering diagram analysis, Principal Component's analysis to explore some of the process variables and to find correlation to burst resistance. Eight variables of the process were investigated and according to the analysis two variables showed a correlation to the burst resistance. A very interesting detail of these variables was hidden in the process and very difficult to vision in the correlation with the burst characteristics however one variable was positive and the other negative in correlation to the burst test results.

There is a large variation in the results of the durability of friction facings in field applications and in most cases there is very little information about the conditions in which the vehicle operated and therefore it was decided to developed a test procedure capable of containing all the different conditions of a vehicle. For this works statistical applications such as DOE (Experimental Design for Experiment) were used to help in planning and to obtain of equations of the tests results and Weibull curves for statistical analysis and comparison of failure mode. By this mean, it was possible to determine a correlation of the results on wear between the bench test and mileage covered on vehicle up to total wear. Therefore it is new possible to estimate the durability of friction facing on vehicles based on bench tests and also obtain knowledge about the behave of the material relative to energy and working temperature.