Desenvolvimento de metodologia integrada para definição de objetivos de desempenho vibro-acústicos a partir do estudo de caso de Booming Noise

Abstract

The demand for comfort in the automotive industry grows with each passing year, revealing the concern of consumers with NVH (noise, vibration and harshness) aspects. The internal noise of a vehicle is associated with the vibration-acoustic performance of several individual components through the transmission paths (air-borne or structure-borne) and depends on the way the sources are integrated, which are: engine, wheels, suspension, intake, exhaust, aerodynamics, etc. In order to determine the desired internal noise level during the development phase of a project, a series of experimental methodologies and techniques must be applied to achieve performance targets for each component. The Transfer Path Analysis (TPA) technique allows to specify the contribution of each source in the internal noise composition, and could be crucial for the vehicle target setting methodology enhancement, as proposed by this work. To evaluate aspects of integration between the NVH performance objectives and coupling effects, it is aimed to elaborate a case study of the occurrence of Booming Noise in the rotation range of 3600-4200rpm, stratifying the individual contribution of each source and path, validating all hypotheses by experimental tests, in a way to identify the root cause of the problem that involves multifactorial conditions of subsystems vibration. The results show that the phenomenon occurs by the joint action of acoustic cavity mode coupling and high levels of excitation with structural sensitivity on the mounting at the right side of the engine, which is determined as the root cause of the Booming Noise. In addition, it is proposed that the investigation of the vibration-acoustic coupling occurrence be always carried out at initial stages of NVH vehicle target setting, aiming to anticipate and correct future problems, since it allowed the identification of important aspects of the vehicle physical behavior on this study