Academic literature on the topic 'NVH'

This master thesis is focused on the diagnostics of vibrations and noise of an internal combustion engine. The work also includes a summary of the current state of knowledge in which the quantities used, transmission paths, measuring devices and the possibilities of performing frequency analysis are analysed. As part of the technical experiment on which this work is based, vibrations and noise on the tractor engine are measured. The obtained data are then further processed using the BK Connect program. Subsequently, a frequency analysis is performed, specifically an order analysis. The conclusion of the analysis consists of an evaluation of individual orders that cause excitation that occur in the investigated motor.

This master’s thesis deals with determination of NVH parameters of the gearbox housing for electric vehicle. The introduction part is focused on the theoretical knowledge of this issue. Subsequently, the deviations of geometry on the gearbox were measure by 3D scan method. The next part of thesis is focused on the modal analysis, which is solved by numerical approach and followed by experimental verification. During the numerical calculation solving, the influence of the screw preloading on the modal properties of the structure, was also taken into account. Numerical harmonic analysis was then performed and the results were compared with the experimental approach. The conclusion is devoted to material damping and comparison of the individual results.

This master’s thesis deals with determination of NVH parameters of the gearbox housing. Introductory part is focused on the necessary theoretical knowledge. Subsequently, it contains the modal analysis with the computational and experimental approach, which are being compared to each other. In the case of the computational approach, analysis of the influence of bolt pretension on the modal properties is also involved. The thesis continues with the harmonic analysis with the computational and experimental approach, including their mutual comparison. Based on these analyses, design modifications for improvement of the NVH parameters are designed at the end of the thesis, which are being compared to each other and to the original geometry, using the computational approach.

The aim of this thesis is examination and verification of numeric model for solving acoustics and vibration problems. Specifically, we are speaking about cast iron plate machined from gearbox. Main objectives of this work is set of experimental and numerical analysis at this simplified part with follow-up numerical model, where same analyses examining not only structure, but especially acoustic space around were performed. Due to this we were able to compare data between experimental and numerical analyses and to be able to prove or disprove functionality and limitation of numerical model.

This Diploma Thesis is dedicated to solve the source of noise, observed during braking processes on tested vehicle, called Gouki noise and has been worked out in corporation with Federal Mogul company. The aim of this work to create test methology, which allows to experimentally detect the source of undesirable noise and eventually suggest next steps in its prevention.

Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2007.<br>Noise, Vibrations and Harshness (NVH) characteristics are becoming ever more significant in today’s vehicle manufacturing industry. Similar to good vibration and harshness characteristics, the perception of a vehicle’s quality is enhanced by a well sounding vehicle interior. This study’s main aim was to develop objective equations to directly optimise interior sound quality of light commercial vehicles ( ½ ton LCVs) on the South African market. The effects the noise of the engine, the wind and road/tyre interaction during steady-state conditions have on the interior sound quality of eleven comparable vehicles was investigated with the aid of a binaural head. Steady-state condition in this content refers to the fact that vehicles were tested at constant speeds, no acceleration involved. A strong emphasis was laid on the influence road noise has on the interior sound quality of LCVs. Other objectives for the thesis were, to provide a method to benchmark the interior SQ of LCVs and to develop target values for objective metrics for these vehicles. Establishing a comprehensive literature survey formed another objective of this study. It seeks to provide a summary of the modern SQ analysis procedure and the findings of a number of studies. The survey also presents an opportunity to compare this thesis’s results with previous studies. A last objective was to develop a list of possible hardware modifications that would improve the vehicle interior sound quality, influenced by different noise sources. A strong correlation between vehicle and engine speed and Zwicker loudness as well as Aure sharpness was found, for all test conditions. The road surface roughness was observed to also have a strong influence on the objective metrics of vehicle interior SQ. Loudness was found to be around 25% higher and sharpness around 5.6% lower in vehicles driving on rough tar roads than on smooth roads. Good correlations between a newly developed metric (the SPF), an equation in Zwicker loudness and Aure sharpness, and subjective ratings was obtained for a number of test conditions. Four objective equations, as well as target values for loudness and sharpness have been developed to objectively optimise the sound quality of LCVs. Benchmarking interior sound quality utilising the developed equations, will ensure continuous improvements in the SQ sector for future LCVs.

Este trabalho visa o desenvolvimento de um modelo em elementos finitos de elementos de dissipação vibratória de base betuminosa, chamados comumente de deadeners. O modelo baseia-se no algoritmo comercial MSC/NASTRAN e é correlacionado e verificado com base em dados experimentais de laboratório. O resultado final deste projeto é um modelo para os deadeners que pode ser utilizado em modelos de elementos finitos de veículos completos, facilitando assim a definição da melhor localização dos mesmos no veículo bem como a otimização de seu uso. O modelo tem melhor resultado em termos de amplitude para frequências abaixo de 200Hz, porém apresenta tendências de superestimar o efeito do amortecimento nos picos de ressonância<br>This project aims the development of a finite element model of vibration dissipating elements of bituminous base, commonly called \"deadeners. The proposed model is based on the finite element commercial algorithm MSC/NASTRAN and is correlated and verified on experimental data from laboratory. The end result of this project is a model for \"deadeners\" which can be used in finite element models of complete vehicles, thus facilitating better definition of their location in the vehicle as well as the optimization of its use. The model has a better result in terms of amplitude for frequencies below 200 Hz, but shows a tendency to overestimate the effects of damping at the resonance peaks

Thesis (S.M.)--Massachusetts Institute of Technology, System Design and Management Program, 2008.<br>Includes bibliographical references (p. 134-137).<br>This research is comprised of a detailed study of attribute management processes at a North American Automotive OEM (NA OEM) that has just introduced a new product development system intended to drastically reduce product cycle time and expedite product time to market. In specifics, the product development processes and organization that manage the delivery of a vehicle system design that meets or exceeds customer expectations for noise, vibration and harshness (NVH) are studied. Systems engineering principles, methods and tools are applied to the current processes to assess if process lead time, resources and product quality improvement can be realized. The systems engineering Design Structure Matrix (DSM) method for product development process modeling is applied to the current process used to manage the highly cross functional vehicle attribute known as second order NVH. Second Order NVH represents a vehicle system attribute that is owned by a single subsystem, yet controlled by design parameters owned by many other subsystems. The DSM method enables the NA OEM PD organization to understand the current process of managing this highly cross functional attribute and serves as a powerful tool for process restructuring. Process data is collected such that the DSM process model can be input into a simulation program which predicts stochastic process lead time for the current process and tests the impact of process restructuring ideas. This research also studies the methods and tools used at NA OEM to facilitate vehicle attribute trade-off, decomposition and cascade to the subsystem and component level. Then, a systems engineering approach is suggested to improve the attribute engineering knowledge base which could enable improved attribute trade-off, decomposition and cascade.<br>by Michelle Lorraine Sacka.<br>S.M.