EB2013-NVH-029 ON THE IMPROVEMENT OF NVH SIMULATIONS USING UNCERTAIN FE BRAKE MODELS 1 Tison, Thierry * , 1 Massa, Franck, 1 Cazier, Olivier, 1 Heussaff, Arnaud, 1 Lallemand, Bertrand, 3 Fernandes Nunes, Ronaldo 1 LAMIH UMR CNRS 8201, France. 3 Daimler, Germany KEYWORDS – Squeal, Uncertainty, Instability analysis, Design of Experiments, FE brake disk model ABSTRACT - Numerical simulation of mechanical phenomena is under constant development due to the exponential growth of computer power. This facilitates the fast implementation of more and more fine and complex numerical studies performed at different scales. At the preliminary design stage, optimization strategies and non-deterministic methodologies are also increasingly common. This paper presents results from both experimental and numerical designs of experiments (DOE) for the study of the influence of the variability linked to the disk brake squeal. The objective is to assess the extent to which more representative information can allow the designer to evaluate solutions towards the squealing phenomenon. A key point is to define a strategy for the management of the large amount of solutions both for the complex frequency analysis and the transient analysis. Another key point is whether the criteria used for deterministic studies, will be able to aggregate all the behaviours of a family of braking systems. Methodologies are proposed to answer these questions and numerical results show the benefits of enrichment of numerical simulations for squealing phenomena detection. INTRODUCTION During cars and trains braking, instabilities generated by friction are source of undesirable squealing noise, which can reach more than 100 dB. Brake squeal noise is generally defined at frequency upper than 1 kHz and is generated by vibrations of different components of the braking system. The squeal mainly occurs during constant or park brakings. This last situation corresponds to low speed (from 0 to 30 km/h) and intermediate braking pressure (from 15 to 30 bars). Squeal, generally associated to instability by mode coupling (1, 2), is of variable nature because of its dependency to numerous endogenous and exogenous parameters of the braking system. It is directly related to friction between the disc and the pads. Environmental criteria for noise pollution being more and more strict, understanding of squeal phenomenon is a current challenge for the scientific community and industrials of the domain. Noise emanating from brake systems is a source of considerable discomfort and leads to dissatisfaction of the customers for the automotive industry or dissatisfaction of the passengers both inside and outside the trains in stations. Noise reduction at the source is the key point to reduce its impact in transportation. A complete control of the mechanisms of squeal occurrence is then required at the design phase. Although it is studied from a theoretical and a phenomenological point of view for a long time and despite a multitude of technical solutions, squeal phenomenon is difficult to control in practice. One of the most difficulties is related to its fugitive nature which can be linked to several kinds of uncertainties identified at different steps of the production of braking systems (3) and their functioning (4). Indeed, different factors may be in cause. Manufactured systems have not always the same characteristics which lead to different behaviour from brake