Vibroacoustics

Advanced Computational Vibroacoustics presents an advanced computational method for the prediction of sound and structural vibrations, in low- and medium-frequency ranges - complex structural acoustics and fluid-structure interaction systems encountered in aerospace, automotive, railway, naval, and energy-production industries. The formulations are presented within a unified computational strategy and are adapted for the present and future generation of massively parallel computers. A reduced-order computational model is constructed using the finite element method for the damped structure and the dissipative internal acoustic fluid (gas or liquid with or without free surface) and using an appropriate symmetric boundary-element method for the external acoustic fluid (gas or liquid). This book allows direct access to computational methods that have been adapted for the future evolution of general commercial software. Written for the global market, it is an invaluable resource for academic researchers, graduate students, and practising engineers.

This text provides the foundation material for solving problems in vibroacoustics. These include the prediction of structural vibration levels and sound pressure levels in enclosed spaces resulting from known force or acoustic pressure excitations and the prediction of sound levels radiated by vibrating structures. The book also provides an excellent theoretical basis for understanding the processes involved in software that predicts structural vibration levels and structural sound radiation resulting from force excitation of the structure, as well as sound levels in enclosed spaces resulting from vibration of part of the enclosing structure or resulting from acoustic sources within the enclosure. The book is written in an easy to understand style with detailed explanations of important concepts. It begins with fundamental concepts in vibroacoustics and provides a framework for problem solution in both low and high frequency ranges. It forms a primer for students, and for those already well versed in vibroacoustics, the book provides an extremely useful reference. It offers a unified treatment of both acoustics and vibration fundamentals to provide a basis for solving problems involving structural vibration, sound radiation from vibrating structures, sound in enclosed spaces, and propagation of sound and vibration.

The subject of vibro-acoustics is important for the design of machine elements and structures, to minimize sound generated by them. For better machine designing, it is necessary for machine designers (mechanical engineers) to have a thorough knowledge of vibro-acoustics. Furthermore, since the design cycles of machines have become shorter, designers will have to design quiet machines at the drawing-board stage rather than applying "band-aid" techniques after the machine has been built. Although there is common ground in the treatment of acoustics, the subject of vibration is not very fortunate. Those interested in low-frequency vibration are generally concerned with the modal approach of using natural frequencies and mode shapes, whereas those interested in vibro-acoustics in medium and high frequencies are generally concerned with the wave approach. Since both modal and wave approaches have their advantages, it is a good idea to study both together to get the best out of them. This is useful for a better understanding the physics of vibro-acoustics. Written for students and professionals interested in gaining knowledge, this book systematically integrates the relevant aspects of vibro-acoustics from various viewpoints.

This text provides the foundation material for solving problems in vibroacoustics. These include the prediction of structural vibration levels and sound pressure levels in enclosed spaces resulting from known force or acoustic pressure excitations and the prediction of sound levels radiated by vibrating structures. The book also provides an excellent theoretical basis for understanding the processes involved in software that predicts structural vibration levels and structural sound radiation resulting from force excitation of the structure, as well as sound levels in enclosed spaces resulting from vibration of part of the enclosing structure or resulting from acoustic sources within the enclosure. The book is written in an easy to understand style with detailed explanations of important concepts. It begins with fundamental concepts in vibroacoustics and provides a framework for problem solution in both low and high frequency ranges. It forms a primer for students, and for those already well versed in vibroacoustics, the book provides an extremely useful reference. It offers a unified treatment of both acoustics and vibration fundamentals to provide a basis for solving problems involving structural vibration, sound radiation from vibrating structures, sound in enclosed spaces, and propagation of sound and vibration.

The book describes analytical methods (based primarily on classical modal synthesis), the Finite Element Method (FEM), Boundary Element Method (BEM), Statistical Energy Analysis (SEA), Energy Finite Element Analysis (EFEA), Hybrid Methods (FEM-SEA and Transfer Path Analysis), and Wave-Based Methods. The book also includes procedures for designing noise and vibration control treatments, optimizing structures for reduced vibration and noise, and estimating the uncertainties in analysis results. Written by several well-known authors, each chapter includes theoretical formulations, along with practical applications to actual structural-acoustic systems. Readers will learn how to use vibroacoustic analysis methods in product design and development; how to perform transient, frequency (deterministic and random), and statistical vibroacoustic analyses; and how to choose appropriate structural and acoustic computational methods for their applications. The book can be used as a general reference for practicing engineers, or as a text for a technical short course or graduate course.

This book is a printed edition of the Special Issue "Advances in Vibroacoustics and Aeroacustics of Aerospace and Automotive Systems" that was published in Applied Sciences

VIBROACOUSTIC SIMULATION Learn to master the full range of vibroacoustic simulation using both SEA and hybrid FEM/SEA methods Vibroacoustic simulation is the discipline of modelling and predicting the acoustic waves and vibration of particular objects, systems, or structures. This is done through finite element methods (FEM) or statistical energy analysis (SEA) to cover the full frequency range. In the mid-frequency range, both methods must be combined into a hybrid FEM/SEA approach. By doing so, engineers can model full frequency vibroacoustic simulations in complex technical systems used in aircraft, trains, cars, ships, and satellites. Indeed, hybrid approaches are increasingly used in the automotive, aerospace, and rail industries. Previously covered primarily in scientific journals, Vibroacoustic Simulation provides a practical approach that helps readers master the full frequency range of vibroacoustic simulation. Through a systematic approach, the book illustrates why both FEM and SEA are necessary in acoustic engineering and how both can be used in combination through hybrid methodologies. Striking a crucial balance between complex theories and practical applications, the text provides real-world examples of vibroacoustic simulation, such as fuselage simulation, interior-noise prediction for electric and combustion vehicles, train profiles, and more, to help elucidate the concepts described within. Vibroacoustic Simulation also features: A balance of complex theories with the nuts and bolts of real-world applications Detailed worked examples of junction equations Case studies from companies like Audi and Airbus that illustrate how the methods discussed have been applied in real-world projects A companion website that provides corresponding Python codes for all examples, allowing readers to work through the examples on their own Vibroacoustic Simulation is a useful reference for acoustic and mechanical engineers working in the automotive, aerospace, defense, or rail industries, as well as researchers and graduate students studying acoustics.

The subject of vibro-acoustics is important for the design of machine elements and structures, to minimize sound generated by them. For better machine designing, it is necessary for machine designers (mechanical engineers) to have a thorough knowledge of vibro-acoustics. Furthermore, since the design cycles of machines have become shorter, designers will have to design quiet machines at the drawing-board stage rather than applying "band-aid" techniques after the machine has been built. Although there is common ground in the treatment of acoustics, the subject of vibration is not very fortunate. Those interested in low-frequency vibration are generally concerned with the modal approach of using natural frequencies and mode shapes, whereas those interested in vibro-acoustics in medium and high frequencies are generally concerned with the wave approach. Since both modal and wave approaches have their advantages, it is a good idea to study both together to get the best out of them. This is useful for a better understanding the physics of vibro-acoustics. Written for students and professionals interested in gaining knowledge, this book systematically integrates the relevant aspects of vibro-acoustics from various viewpoints.