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Gears are essential parts of many precision power transmitting machines such as automobiles. The major functions of a gearbox are to transform speed and torque in a given ratio and to change the axis of rotation. Planetary gears yield several advantages over conventional parallel shaft gear systems: They produce high speed reductions in compact spaces, a greater load sharing, a higher torque to weight ratio, diminished bearing loads, and reduced noise and vibration. They are used in automobiles, helicopters, aircraft engines, heavy machinery, and a variety of other applications. Despite their advantages, the noise induced by the vibration of planetary gear systems remains a key concern. Planetary gears have received considerably less research attention than single mesh gear pairs. There is a particular scarcity of analysis of two planetary gear systems and their dynamic response. Hence, this book focuses on the study of two PGTs with different phasing (angular positions) while every individual set remains unchanged.

Vibration and noise are two interrelated terms in the field of mechanical engineering. Vibration is caused by unbalanced inertial forces and moments whereas noise is the result of such vibrations. Noisy machines have always been a matter of concern. Lesser vibration ensures manufacturing to closer tolerances, lesser wear and tear, and longer fatigue life. Hence, a quieter machine is more cost-effective in the long run. It is now well understood that a quieter machine is in every way a better machine.This book deals with such industrial and automotive noise and vibration, their measurement and control. This textbook stresses on physical concepts and the application thereof to practical problems. The author's four decades of experience in teaching, research and industrial consultancy is reflected in the choice of the solved examples and unsolved problems.The book targets senior undergraduate students in mechanical engineering as well as designers of industrial machinery and layouts. It can readily be used for self-study by practicing designers and engineers.

Large Eddy Simulation (LES) is a high-fidelity approach to the numerical simulation of turbulent flows. Recent developments have shown LES to be able to predict aerodynamic noise generation and propagation as well as the turbulent flow, by means of either a hybrid or a direct approach. This book is based on the results of two French/German research groups working on LES simulations in complex geometries and noise generation in turbulent flows. The results provide insights into modern prediction approaches for turbulent flows and noise generation mechanisms as well as their use for novel noise reduction concepts.

This leading noise resource is specifically written for those with a technical interest in noise and for anyone who desires an improved general understanding of the subject. It addresses noise-related issues within the workplace and those arising in the community. Topics include: room noise criteria; speech and signal detection; community noise of hearing loss due to the noise exposure; prediction; and standards and regulations. Each of its 18 chapters have been peer-reviewed and contain numerous citations to the current literature, complemented by the expansive appendix on references for good practice.