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The improvement of motor’s power requires consequently the improvement in brake system also. The kinetic energy of moving vehicles is transformed in a big part of heat, but there is a part that can be transformed in vibration and sound pressure. One of these vibration and sound pressure complain is known as howl noise. The howl noise complain is very intense and uncomfortable for passengers and pedestrians. Today, the customers spend a lot of money in his vehicles comfort and this disorder can’t occur. This paper presents a methodology which uses Experimental Modal Analysis (EMA) and Operational Modal Analysis (OMA) to survey the dynamic behavior of suspension and brake systems at the howl noise occurrence condition.

The vibroacoustic comfort sense inside vehicles is a topic of major concern in current automotive industry. Moreover, the increase in demand of users and the competition in the automotive sector lead automakers to invest in developing more comfortable vehicles. Thus, even noises in specific usage scenarios and short time is claimed. This paper raises the cause and proposes solutions to a noise from the brake system known as "Moan Noise". This noise happens under specific conditions of use, but is easily identified by the user. Moreover, it is a random phenomenon and difficult to characterize. Thus, this study shows a methodology to survey the phenomenon under study and validation of proposals for improvement through operational techniques and experimental modal analysis.

The automotive industry currently has a big concern with the vibro-acoustic comfort. The growth of concurrence and the clients requirement becomes necessary the researches in new techniques for analysis and improvement. Hence many vibro-acoustic phenomena causes uncomfortable noises in a vehicle. One of this noises is descendant of braking system and is known as Bus Noise. This paper presents a methodology which uses Experimental Modal Analysis (EMA) and Operational Modal Analysis (OMA) to survey the dynamic behavior of suspension and brake systems at the Bus Noise occurrence condition.

The vibroacoustic comfort sense inside vehicles is a topic of major concern in current automotive industry. Moreover, the increase in demand of users and the competition in the automotive sector lead automakers to invest in developing more comfortable vehicles. Thus, even noises in specific usage scenarios and short time is claimed. This paper raises the cause and proposes solutions to a noise from the brake system known as “Moan Noise”. This noise happens under specific conditions of use, but is easily identified by the user. Moreover, it is a random phenomenon and difficult to characterize. Thus, this study shows a methodology to survey the phenomenon under study and validation of proposals for improvement through operational techniques and experimental modal analysis.

With the purpose to identify the root cause of increased levels of vibration felt at idle speed in a popular vehicle prototype a study was conducted using techniques for analysis of vibration transmission between components of a vehicle, using Mechanical Vibrations Analysis and Operational Modal Analysis, for the analysis of the operational modes was used ODS - Operational Deflection Shape technique which is possible only see the shapes related to probable modes. The experimental results were compared with results for the modal analysis by Finite Element Method (FEM). The vehicles used are identical prototypes, but with different levels of vibration. Therefore, to study there is a vehicle with satisfactory levels and a second with unsatisfactory levels. This study demonstrates the methodology used to identify the cause of the different behaviors between cars and also discuss the improvements made in the body according to the results of the numerical experimental confrontation.

The noise made from transmissions system of a vehicle is one of big worries of automobilist industry. This kind of noise also known as “Transmission Noise” is totally related to limitation of drive comfort. Actually there are different types of noise from transmission system, one of these is known as “Whine Noise”. Because of the vehicle market competitive and of the raise of customers demanding find a solution to eliminate or to decrease these unpleasant effects became an important job. In this sense, this work describes a new methodology for identification of main reasons responsible for Whine Noise in prototype of a popular passenger vehicle through the Numerical and Experimental Confront. In this study were used techniques of Operational Modal Analysis (ODS technique), Numerical Simulation, Vibration and Noise Analysis.