On the influence of multiple contact conditions on brake squeal

This study focuses on squeal noise prediction for an automotive brake system. For this purpose, a stability study of a finite element model of the brake system is carried out. For the determination of the squeal propensity of a brake system via finite element models, the commonly used approach consists in considering only a friction coefficient at the pad-disc interface. However, numerous other contacts exist in a brake system. In the present study, the influence of several contacts between the caliper, the bracket, the pad and the piston is studied. It turns out that the consideration of these numerous contacts has a real impact on the stability results and can not therefore be neglected. Indeed, a high dispersion of results for the system’s eigenvalues indicating strong modifications of the stability behavior and thus of the squeal propensity is observed when different contact conditions are considered. This study insights the necessity to take into account of all contact conditions during the design process of brake systems

Prediction and analysis of quasi-periodic solution for friction-induced vibration of an industrial brake system with the Generalized Modal Amplitude Stability Analysis

Brake squeal is a major issue for car manufacturers as it is the reason for the return of many vehicles to customer services, representing high costs for the companies. To meet customer’s expectations, squeal must be accurately predicted during the design process. In the context of the automotive industry, squeal usually refers to friction-induced vibrations that generate noise. The main methodology employed nowadays for friction-induced vibrations prediction of industrial systems is the well-known complex eigenvalue analysis (CEA) despite its limitations. The latter suffers from an under- or over-predictive aspect and the vibration amplitudes cannot be estimated. A recent approach, called the generalised modal amplitude stability analysis (GMASA), has been developed as a complementary approach of the CEA to identify the modes involved in the nonlinear dynamic response of systems subjected to friction-induced vibrations and to approximate the quasi-periodic oscillations. The objective of this paper is to predict the nonlinear dynamic response of a full industrial automotive brake system. The GMASA is employed to predict its nonlinear dynamic response. It is demonstrated that when the CEA predicts a single unstable mode, two are actually involved in the nonlinear dynamic response. The quasi-periodic oscillations are analysed, as well as the evolution of the contact conditions at the pad/disc interface and exhibits the presence of micro-impacts

Mise en place d’une technique numérique pour l’estimation de vibrations non-linéaires auto-entretenues avec frottement: Application à la prédiction du crissement de frein automobile

International audienceCe papier présente une approche non-linéaire permettant d'approximer le comportement vibratoire non-linéaire dans le cas où plusieurs instabilités sont impliquées dans la réponse du système. Cette méthode dénommée MASA (Modal Amplitude Stability Analysis) est complémentaire de l'ana-lyse aux valeurs propres complexes. Dans un premier temps, les aspects théoriques de la méthode sont présentés. Puis, le modèle éléments finis du frein servant d'illustration est présenté. Enfin, la méthode non-linéaire est appliquée sur le modèle afin de prédire la réponse dynamique de celui-ci

Generalized Modal Amplitude Stability Analysis for the prediction of the nonlinear dynamic response of mechanical systems subjected to friction-induced vibrations

International audienceThe numerical prediction of the dynamic behaviour of mechanical systems subjected to friction-induced vibrations is still a tedious problem. Different methodologies exist nowadays to study it.The first one is the complex eigenvalue analysis, which is widely used by the scientists and the industrials to predict the appearance of instabilities despite its disadvantages. Other methodologies, namely temporal integration and frequential approaches, have been developed to determine the transient and/or the steady-state response toassess the history of the dynamic response, and so to identify the unstable modes involved in the nonlinear dynamic response as well as the vibration levels. However, because of their complex implementation, their high numerical cost and sometimes the strong assumptions made on the form of the solutions, these methods are not widely and currently used in industry. To cope with the limitations of the CEA, namely the over- or under-predictability and the lack of information about modal participations in the nonlinear dynamic response, developing complementary tools is necessary. Thus, this paper is devoted to the extension and generalization of a nonlinear approach, called the modal amplitude stability analysis, to the multi-instability case. The method, called the Generalized Modal Amplitude Stability Analysis (GMASA), allows to identify the evolutions and contributions of unstable modes involved in the nonlinear self-sustaining vibration response and to estimate the limit cycles. The method is applied on a phenomenological system for which it is easy to provide an understanding of the unstable mode(s) contribution to the nonlinear dynamic response of the system and for which the calculations can be performed with reasonable computational times. Thus, the efficiency and validity of the GMASA approach are investigated by comparing the GMASA results with those of the reference results based on temporal approach

Kriging Surrogate Models for Predicting the Complex Eigenvalues of Mechanical Systems Subjected to Friction-Induced Vibration

International audienceThis study focuses on the kriging based metamodeling for the prediction of parameter-dependent mode coupling instabilities.The high cost of the currently used parameter-dependent Complex Eigenvalue Analysis (CEA) has induced a growing need foralternative methods. Hence, this study investigates capabilities of kriging metamodels to be a suitable alternative. For this aim,kriging metamodels are proposed to predict the stability behavior of a four-degree-of-freedom mechanical system submitted tofriction-induced vibrations. This system is considered under two configurations defining two stability behaviors with coalescencepatterns of different complexities. Efficiency of kriging is then assessed on both configurations. In this framework, the proposedkriging surrogate approach includes a mode tracking method based on the Modal Assurance Criterion (MAC) in order to followthe physical modes of the mechanical system. Based on the numerical simulations, it is demonstrated by a comparison with thereference parameter-dependent CEA that the proposed kriging surrogate model can provide efficient and reliable predictions ofmode coupling instabilities with different complex patterns

Squeal analysis based on the effect and determination of the most influential contacts between the different components of an automotive brake system

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Mise en place d’une technique numérique pour l’estimation de vibrations non-linéaires auto-entretenues avec frottement: Application à la prédiction du crissement de frein automobile

International audienceCe papier présente une approche non-linéaire permettant d'approximer le comportement vibratoire non-linéaire dans le cas où plusieurs instabilités sont impliquées dans la réponse du système. Cette méthode dénommée MASA (Modal Amplitude Stability Analysis) est complémentaire de l'ana-lyse aux valeurs propres complexes. Dans un premier temps, les aspects théoriques de la méthode sont présentés. Puis, le modèle éléments finis du frein servant d'illustration est présenté. Enfin, la méthode non-linéaire est appliquée sur le modèle afin de prédire la réponse dynamique de celui-ci

Influence des conditions de contact sur le crissement de frein

International audienceUne étude du crissement de frein est proposée par une analyse de stabilité du système. Le modèle éléments finis utilisé correspond à un frein automobile. Généralement, les seules interfaces frottantes considérées pour l’étude du crissement correspondent à l’interface disque-plaquettes. Dans ce papier, l’influence de divers contacts au niveau de l’étrier , de la plaquette et du piston sont étudiés. Une grande variabilité des résultats est observée en fonction d es états de contacts présents ou non dans le frein