Download or read book Vibro Acoustics of Lightweight Sandwich Structures written by Tianjian Lu and published by Springer. This book was released on 2014-07-08 with total page 350 pages. Available in PDF, EPUB and Kindle. Book excerpt: Vibro-Acoustics of Lightweight Sandwich Structures introduces the study of the coupled vibration and acoustic behavior of lightweight sandwich structures in response to harmonic force and sound pressure. This book focuses on the theoretical modeling and experimental investigation of lightweight sandwich structures in order to provide a predictive framework for vibro-acoustic characteristics of typical engineering structures. Furthermore, by developing solution tools, it concentrates on the influence of key systematic parameters leading to effective guidance for optimal structure design toward lightweight, high-stiffness and superior sound insulation capability. This book is intended for researchers, scientists, engineers and graduate students in mechanical engineering especially in structural mechanics, mechanics and acoustics. Fengxian Xin and Tianjian Lu both work at the School of Aerospace, Xi’an Jiaotong University.

Download or read book Stability and Vibrations of Thin Walled Composite Structures written by Haim Abramovich and published by Woodhead Publishing. This book was released on 2017-05-29 with total page 772 pages. Available in PDF, EPUB and Kindle. Book excerpt: Stability and Vibrations of Thin-Walled Composite Structures presents engineering and academic knowledge on the stability (buckling and post buckling) and vibrations of thin walled composite structures like columns, plates, and stringer stiffened plates and shells, which form the basic structures of the aeronautical and space sectors. Currently, this knowledge is dispersed in several books and manuscripts, covering all aspects of composite materials. The book enables both engineers and academics to locate valuable, up-to-date knowledge on buckling and vibrations, be it analytical or experimental, and use it for calculations or comparisons. The book is also useful as a textbook for advanced-level graduate courses. - Presents a unified, systematic, detailed and comprehensive overview of the topic - Contains contributions from leading experts in the field - Includes a dedicated section on testing and experimental results

Download or read book Vibro Acoustics Volume 2 written by Anders Nilsson and published by Springer. This book was released on 2015-09-15 with total page 453 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Vibro Acoustics written by Anders Nilsson and published by Springer. This book was released on 2016-12-01 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This is a set of Three volume books:Vibro-Acoustics, Volume 1, Second Edition; Vibro-Acoustics, Volume 2, Second Edition; Vibro-Acoustics, Volume 3, Second Edition. This three-volume book gives a thorough and comprehensive presentation of vibration and acoustic theories. Different from traditional textbooks which typically deal with some aspects of either acoustic or vibration problems, it is unique of this book to combine those two correlated subjects together. Moreover, it provides fundamental analysis and mathematical descriptions for several crucial phenomena of Vibro-Acoustics which are quite useful in noise reduction, including how structures are excited, energy flows from an excitation point to a sound radiating surface, and finally how a structure radiates noise to a surrounding fluid. Many measurement results included in the text make the reading interesting and informative. Problems/questions are listed at the end of each chapter and the solutions are provided. This will help the readers to understand the topics of Vibro-Acoustics more deeply. The book should be of interest to anyone interested in sound and vibration, vehicle acoustics, ship acoustics and interior aircraft noise.

Download or read book Sound Radiation Responses and Acoustic Behvior of Sandwich Panel written by Luyao Wang and published by . This book was released on 2019 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Sandwich structures with decent sound insulation and absorption properties have been widely used in the engineering fields such as aerospace engineering, marine engineering and civil and construction engineering. Investigations on the acoustic behavior of sandwich structures is of practical importance, not only for engineers but to researchers in the field. A numerical study of the vibro-acoustic and sound transmission loss (STL) of an aluminum honeycomb core sandwich panel with fabric-reinforced graphite (FRG) composite face sheets is performed in the present research. The honeycomb sandwich structure, faced with an FRG composite face sheet, has acoustic advantages over other types of sandwich structures commonly used in the field. The effects of different boundary conditions and geometric properties of the FRG faced honeycomb structure on the stiffness of the structure are evaluated. The effects of the stiffness on the acoustic performance of the structure are investigated. Truss core sandwich panels filled with sound absorbing materials are also studied numerically for the panels' vibration responses and STL behavior. The performances of a polyurethane (PUF)-foam-filled truss core sandwich panel and a wood-board-filled truss core sandwich panel are compared. The wood based sandwich panel shows advantages with compatible acoustic performance and environmental-friendly characteristics over the PUF foam panel. The acoustic behavior of the wood-based porous media, with varying airflow properties, are investigated. The most significant factor affecting the vibro-acoustic responses of the panel are identified. The wood-based-porous-medium-filled truss core sandwich panel with various face sheet materials are analyzed. A truss core 2 sandwich panel is designed with the optimal combination of wood-board and face sheet materials. Numerical models, based on the sandwich theory, are established based on the assumption the sandwich core is an orthotropic structural layer. The radiated sound power from the panel is quantified with the Rayleigh integral method. A random diffuse field is used as an incident sound source and is derived with the finite element method using ACTRAN. The numerical results generated with the implementation of the models are validated with experimental data available in the literature. The findings provide guidance for selecting and designing honeycomb core and truss core sandwich panels with decent acoustic properties for engineering applications. The developed approach presents practical significance for quantitatively evaluating and designing sandwich panels with high efficiency and effectiveness, when the acoustic and vibrational performance of the panels need to be considered.

Download or read book Vibro Acoustics Volume 1 written by Anders Nilsson and published by Springer. This book was released on 2015-08-06 with total page 385 pages. Available in PDF, EPUB and Kindle. Book excerpt: This three-volume book gives a thorough and comprehensive presentation of vibration and acoustic theories. Different from traditional textbooks which typically deal with some aspects of either acoustic or vibration problems, it is unique of this book to combine those two correlated subjects together. Moreover, it provides fundamental analysis and mathematical descriptions for several crucial phenomena of Vibro-Acoustics which are quite useful in noise reduction, including how structures are excited, energy flows from an excitation point to a sound radiating surface, and finally how a structure radiates noise to a surrounding fluid. Many measurement results included in the text make the reading interesting and informative. Problems/questions are listed at the end of each chapter and the solutions are provided. This will help the readers to understand the topics of Vibro-Acoustics more deeply. The book should be of interest to anyone interested in sound and vibration, vehicle acoustics, ship acoustics and interior aircraft noise. This is the first volume, and covers the following topics: Mechanical systems with one degree of freedom, Frequency domain, Waves in solids, Interaction between longitudinal and transverse waves, General wave equation, Wave attenuation due to losses and transmission across junctions, Longitudinal vibrations of finite beams, Flexural vibrations of finite beams, Flexural vibrations of finite plates.

Download or read book Issues in Acoustic and Ultrasound Technology 2012 Edition written by and published by ScholarlyEditions. This book was released on 2013-01-10 with total page 212 pages. Available in PDF, EPUB and Kindle. Book excerpt: Issues in Acoustic and Ultrasound Technology: 2012 Edition is a ScholarlyEditions™ eBook that delivers timely, authoritative, and comprehensive information about Ultrasound Technology. The editors have built Issues in Acoustic and Ultrasound Technology: 2012 Edition on the vast information databases of ScholarlyNews.™ You can expect the information about Ultrasound Technology in this eBook to be deeper than what you can access anywhere else, as well as consistently reliable, authoritative, informed, and relevant. The content of Issues in Acoustic and Ultrasound Technology: 2012 Edition has been produced by the world’s leading scientists, engineers, analysts, research institutions, and companies. All of the content is from peer-reviewed sources, and all of it is written, assembled, and edited by the editors at ScholarlyEditions™ and available exclusively from us. You now have a source you can cite with authority, confidence, and credibility. More information is available at http://www.ScholarlyEditions.com/.

Download or read book Modern Mechanics and Applications written by Nguyen Tien Khiem and published by Springer Nature. This book was released on 2021-09-06 with total page 1137 pages. Available in PDF, EPUB and Kindle. Book excerpt: This proceedings book includes a selection of refereed papers presented at the International Conference on Modern Mechanics and Applications (ICOMMA) 2020, which took place in Ho Chi Minh City, Vietnam, on December 2–4, 2020. The contributions highlight recent trends and applications in modern mechanics. Subjects covered include biological systems; damage, fracture, and failure; flow problems; multiscale multi-physics problems; composites and hybrid structures; optimization and inverse problems; lightweight structures; mechatronics; dynamics; numerical methods and intelligent computing; additive manufacturing; natural hazards modeling. The book is intended for academics, including graduate students and experienced researchers interested in recent trends in modern mechanics and application.

Download or read book Vibration and Acoustic Properties of Honeycomb Sandwich Structures Subject to Variable Incident Plane wave Angle Pressure Loads written by Jiaxue Yan and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Honeycomb structures are widely used in many areas for their material characteristics such as high strength-to-weight ratio, stiffness-to-weight, sound transmission, and other properties. Honeycomb structures are generally constructed from periodically spaced tessellations of unit cells. It can be shown that the effective stiffness and mass properties of honeycomb are controlled by the local geometry and wall thickness of the particular unit cells used. Of particular interest are regular hexagonal (6-sided) honeycomb unit cell geometries which exhibit positive effective Poisson's ratio, and modified 6-sided auxetic honeycomb unit cells with Poisson's ratio which is effectively negative; a property not found in natural materials. One important honeycomb meta-structure is sandwich composites designed with a honeycomb core bonded between two panel layers. By changing the geometry of the repetitive unit cell, and overall depth and material properties of the honeycomb core, sandwich panels with different vibration and acoustic properties can be designed to shift resonant frequencies and improve intensity and Sound Transmission Loss (STL). In the present work, a honeycomb finite element model based on beam elements is programmed in MATLAB and verified with the commercial finite element software ABAQUS for frequency extraction and direct frequency response analysis. The MATLAB program was used to study the vibration and acoustic properties of different kinds of honeycomb sandwich panels undergoing in-plane loading with different incident pressure wave angles and frequency. Results for the root mean square intensity IRMS based on normal velocity on the transmitted side of the panel measure vibration magnitude are reported for frequencies between 0 and 1000 Hz. The relationship between the sound transmission loss computed with ABAQUS and the inverse of the intensity of surface velocity is established. In the present work it is demonstrated that the general trend between the STL pressure response and the inverted intensity metric have similar response characteristics over both the stiffness frequency region and the resonance frequency region, showing that an increase in IRMS corresponds to a decrease in STL. The ABAQUS model was used to verify the MATLAB program for natural frequencies and mode shapes, and to compute the STL on the top surface of the honeycomb sandwich structure. Resonant peaks in the frequency response of intensity and STL are identified with natural frequencies and mode shapes of the honeycomb sandwich structure. A unique feature of this research is the ability to apply the time-harmonic acoustic pressure as a load on the transmitting surface of the honeycomb sandwich panel with variable incident angle ranging between 0° to 90°. When the incident angle is nonzero, the pressure load is complex valued, with sinusoidal distribution, and frequency dependent. The finite element implementation of the complex-valued variable incident pressure distribution is programmed in MATLAB to give complete control of the angle, frequency and distribution. Commercial finite element software such as ABAQUS has limited ability to directly apply frequency dependent and distributed real and imaginary pressure distributions in a direct steady state frequency analysis over a large number of frequency evaluations. In the present work, IRMS results for a family of honeycomb sandwich panels with systematic increment in internal cell wall angle, subject to incremental changes in incident angle pressure loads are studied and compared. Results show that for honeycomb sandwich panels with both positive and negative internal cell wall angle, on average, intensity for the nonzero incident angles is higher than the 0°normal incident angle. For the honeycomb sandwich panels with positive internal angle, the intensity consistently increases with larger nonzero incident angles. Furthermore, under the same incident angle pressure load, the intensity of honeycomb panel with positive internal angle is consistently larger than honeycomb panels with negative internal angles.

Download or read book Automotive Acoustics Conference 2015 written by Wolfgang Siebenpfeiffer and published by Springer Vieweg. This book was released on 2019-08-29 with total page 304 pages. Available in PDF, EPUB and Kindle. Book excerpt: Elektrofahrzeuge sind für Entwickler der Fahrzeugakustik ebenso eine Herausforderung wie eine höhere NVH-Performance durch Leichtbaustrukturen und kleinere Motoren mit Turbolader. Die Automobilforschung muss das Akustikmanagement im Fahrzeug neu denken. Die internationale Automotive Acoustics Conference bietet dazu als Fachtagung das notwendige Expertenwissen, um die künftigen Anforderungen an Antriebsstrang, Antriebssysteme und Fahrzeugarchitekturen zu erfüllen. Simulationsprozesse und Verfahren der Multiphysik sind dabei essenziell, um Ruhe in die Passagierkabine zu bringen. Die Konferenz zur car acoustics bietet dazu neustes Expertenwissen.

Download or read book The AUN SEED Net Joint Regional Conference in Transportation Energy and Mechanical Manufacturing Engineering written by Anh-Tuan Le and published by Springer Nature. This book was released on 2022-05-31 with total page 1402 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book (The AUN/SEED-Net Joint Regional Conference in Transportation, Energy, and Mechanical Manufacturing Engineering) gathers selected papers submitted to the 14th Regional Conference in Energy Engineering and the 13th Regional Conference in Mechanical Manufacturing Engineering in the fields related to intelligent equipment, automotive engineering, mechanical systems and sustainable manufacturing, renewable energy, heat and mass transfer. Under the theme of “Integration and Innovation for Sustainable Development,” This book consists of papers in the aforementioned fields presented by researchers and scientists from universities, research institutes, and industry showcasing their latest findings and discussions with an emphasis on innovations and developments in embracing the new norm, resulting from the COVID-19 pandemic.

Download or read book Advances in Engineering Research and Application written by Kai-Uwe Sattler and published by Springer Nature. This book was released on 2019-11-30 with total page 753 pages. Available in PDF, EPUB and Kindle. Book excerpt: This proceedings volume gathers the outcomes of the International Conference on Engineering Research and Applications (ICERA 2019), which was held at Thai Nguyen University of Technology, Vietnam, on December 1–2, 2019 and provided an international forum for disseminating the latest theories and practices in engineering research and applications. The conference focused on original research work in a broad range of areas, including Mechanical Engineering, Materials and Mechanics of Materials, Mechatronics and Micromechatronics, Automotive Engineering, Electrical and Electronics Engineering, and Information and Communication Technology. By sharing the latest advances in these fields, the book will help academics and professionals alike to revisit their thinking on sustainable development.

Download or read book Vibro Acoustic Sources in Lightweight Buildings written by Andreas Mayr and published by Logos Verlag Berlin GmbH. This book was released on 2010 with total page 321 pages. Available in PDF, EPUB and Kindle. Book excerpt: The work reported in this thesis addresses the problem of structure-borne sound transmission in buildings. Vibrating sources, such as services plant and domestic appliances, transmit vibro-acoustic power, causing noise complaints by occupants in rooms removed from the source room. There is not yet an accepted practical method of predicting the installed power into floors or supporting walls, and thence the resultant sound pressure in rooms. This study concentrates on the prediction of the installed power from mechanical installations in lightweight buildings composed of framed and ribbed plates. To identify the characteristics of such receiver elements, a field survey has been undertaken, which involved measurement of the point and transfer mobilities of common wall and floor structures. It is shown that the range of measured values of receiver point mobility is surprisingly small and that the constructions investigated often displayed thin plate-like characteristics, with relatively small spatial variations in point mobility. These field measurements give support to the notion of averaging over contacts. This single equivalent receiver mobility has been assembled both from measured data and from the approximate method and then used in combination with single equivalent source data, to yield an approximate prediction of the installed power. The agreement obtained between the exact and approximate values allowed consideration of a practical implementation of the approximate prediction method, based on a reception plate method which yields the activity and mobility of the tested machine as single equivalent values.

Download or read book Vibroacoustics of Lightweight Structures with Embedded Acoustic Black Holes written by Yu Xiong and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Interest in lightweight and quiet structures is growing in the aeronautical, automotive, and marine industries. However, lightweight structures can easily result in mechanical vibration and noise issues from an acoustician's view. Therefore, a demand for a novel structure that can be lightweight and quiet is imperative. An acoustic Black Hole (ABH) effect is one of the possible methods to resolve this conflict. The ABH is a practical, lightweight, passive vibration control technique and has been well developed in recent years. In an effort to begin using the ABH effect to design an ABH structure for real applications in the industry, in chapter three of this thesis, a hybrid vibroacoustic analytical model is developed. It allows the engineers to understand the sensitivity of the acoustical responses of the ABH structure with respect to the design variables of material properties and structure dimensions in an analytical form. The hybrid analytical model is then used for optimizing the vibroacoustic responses of an ABH beam structure to provide design guidelines for minimizing the noise radiated by the ABH beam structure through the selection of optimal material properties and structure dimensions. Improving low frequency performance is essential for real applications of ABH structures. In chapter four, by establishing the correlation between local ABH modes and radiation efficiency, the results show the low frequency performance of ABH plates essentially depends on the first low order ABH modes. Following the design guidelines obtained from the hybrid vibroacoustic analytical model, several plates with embedded multiple ABH cells are studied using a structural-acoustics simulation to evaluate and tailor the vibration response and resulting structural-acoustic radiation by attaching discrete tuning masses at the center position of each ABH cell. An appropriate amount of tuning mass (4.7 g) adjusted the reduction dip of radiation efficiency at the critical frequency (2700Hz), showing that a potential improvement could be achieved to mitigate the coincidence dip in sound transmission problems. Non-uniformly distributed tuning masses enhanced the reduction of the plate sound radiation coupling. An additional 4 dB reduction in one-third octave band radiated sound power was achieved, and a total 8 dB reduction was obtained compared to the uniform plate case. The first local ABH modes were tuned to lower frequencies in order to improve the low frequency vibroacoustic performance of the plate structures. Many noise and control applications demand panel structures with high Transmission loss (TL) and low weight. The ABH plates have the potential to act as promising candidates for TL applications. In chapter five, a new multi-scale ABH plate design with two different ABH sizes is proposed. The multi-scale ABH plate results are compared with the results from a single-scale ABH plate, all with and without damping materials and an undamped uniform plate. The measured TL results showed the damped single-scale ABH plate achieved improved TL performance compared with a uniform plate by increasing the TL 5-7 dB at and above the coincidence dip. The new proposed multi-scale ABH plate flattens the TL curve, nearly eliminating the coincidence dip band without adding a net mass compared to the uniform plate. The multi-scale design increased the TL 3 dB relative to the single-scale design, and a total 10 dB TL increase to the undamped uniform plate. Various weights of tuning masses are attached at the center of the ABH cells to manipulate the ABH cut-on at the desired frequency. The results show that adding a tuning mass of 20 g to each large ABH cell, of the damped multi-scale ABH plate, improved the TL 2 dB in the low-frequency bands. The added tuning mass created a series of local resonant and high loss modes in the low-frequency region. The ABH plates not only perform better on TL, but also have less total mass. The damped multi-scale ABH plate is 7\% lighter than the uniform plate. Although the damping materials and tuning masses were applied, the overall weight advantage is still attained. This is the first insight into embedding two different size ABH cells and applying tuning masses to improve the plate TL characteristics.

Download or read book Tailoring the Acoustic Properties of Truss Core Sandwich Structure written by Richard Lee and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Proceedings of the International Symposium on Lightweight and Sustainable Polymeric Materials LSPM23 written by Sanjay Mavinkere Rangappa and published by Springer Nature. This book was released on 2023-11-12 with total page 476 pages. Available in PDF, EPUB and Kindle. Book excerpt: This proceedings book contains papers presented at the International Symposium on Lightweight and Sustainable Polymeric Materials (LSPM23) held on February 17, 2023, and organized by King Mongkut’s University of Technology North Bangkok, Thailand. The papers in this book are presented by academics and industrial practitioners showcasing the latest technological advancements and applications of environmentally friendly polymeric materials with the emphasis on the production of lightweight, low-cost, low-energy-consuming materials with competitive performance. The content of this book appeals to academia and industrial researchers from the fields of polymer chemistry, physics, and materials science.

Download or read book Noise Controlling Casings written by Marek Pawelczyk and published by CRC Press. This book was released on 2022-07-28 with total page 279 pages. Available in PDF, EPUB and Kindle. Book excerpt: Noise-Controlling Casings offers a range of feasible noise-controlling strategies for different kinds of devices generating excessive noise. Depending on the required performance and the availability of energy sources, three solution categories are presented: passive (no external energy is needed, but performance is limited), semi-active (little energy is needed, but performance achieves higher values) and active (best performance, but an external energy source is needed). Two very important benefits of these proposed solutions are global noise reduction (in an entire enclosure or the surrounding space) and compact technology (contrary to other active noise control solutions requiring a large number of secondary sources and distributed sensors). Many of the solutions presented are original approaches by the authors, their own developed concepts and new elements and designs that have gained recognition in prestigious journals. The book provides a theoretical background to the research, looking at system configurations, mathematical modelling, signal processing implementation and numerical analysis. The proposed ideas can be applied to any devices provided they have casings of thin walls or they can be enclosed by casings of thin walls. Applications include industrial devices, household appliances, vehicle or aircraft cabins and more. This book will be of interest to professionals and students in the fields of acoustics, vibration, signal processing, control, automotive and aircraft engineering.