Zhuoma Wang¹, Ruoyan Li^2,3, Wenjing Ye^2,*, Yijun Liu³

The International Conference on Computational & Experimental Engineering and Sciences, Vol.27, No.4, pp. 1-2, 2023, DOI:10.32604/icces.2023.09236

Abstract An acoustic diffuser refers to a device that spreads sound energy uniformly in all directions. Such a device plays a very important role in architectural acoustics, i.e., concert halls and auditoriums. Many designs such as the wellknown Schroeder diffusers [1] have been proposed and developed throughout the past several decades. However, most of these conventional designs achieve uniform sound diffusion by using different air trenches to create a phase shift profile following a specific sequence such as maximum length sequence or quadratic residue sequence derived from the number theory [1,2]. As such, these diffusers have considerable thicknesses, which makes them… More >

Chuang Lu¹, Leilei Chen^2,3, Jinling Luo⁴, Haibo Chen^1,*

CMES-Computer Modeling in Engineering & Sciences, Vol.139, No.1, pp. 847-872, 2024, DOI:10.32604/cmes.2023.044446

Abstract We propose a combined shape and topology optimization approach in this research for 3D acoustics by using the isogeometric boundary element method with subdivision surfaces. The existing structural optimization methods mainly contain shape and topology schemes, with the former changing the surface geometric profile of the structure and the latter changing the material distribution topology or hole topology of the structure. In the present acoustic performance optimization, the coordinates of the control points in the subdivision surfaces fine mesh are selected as the shape design parameters of the structure, the artificial density of the sound absorbing material covered on the… More >

Roman Vinokur^*

Sound & Vibration, Vol.57, pp. 1-13, 2023, DOI:10.32604/sv.2023.041784

Abstract The loss factors and their effects on the magnitude and frequency of resonance peaks in various mechanical systems are reviewed for acoustic, vibration, and vibration fatigue applications. The main trends and relationships were obtained for linear mechanical models with hysteresis damping. The well-known features (complex module of elasticity, total loss factor, etc.) are clarified for practical engineers and students, and new results are presented (in particular, for 2-DOF in-series models with hysteresis friction). The results are of both educational and practical interest and may be applied for NVH analysis and testing, mechanical and aeromechanical design, and noise and vibration control… More >

Yi Sun^1,2,*, Chihua Lu^1,2, Zhien Liu^1,2, Menglei Sun¹, Hao Chen¹

CMES-Computer Modeling in Engineering & Sciences, Vol.135, No.3, pp. 2307-2330, 2023, DOI:10.32604/cmes.2023.025313

Abstract In automotive industries, panel acoustic contribution analysis (PACA) is used to investigate the contributions of the body panels to the acoustic pressure at a certain point of interest. Currently, PACA is implemented mostly by either experiment-based methods or traditional numerical methods. However, these schemes are effort-consuming and inefficient in solving engineering problems, thereby restraining the further development of PACA in automotive acoustics. In this work, we propose a PACA scheme using discontinuous isogeometric boundary element method (IGABEM) to build an easily implementable and efficient method to identify the relative acoustic contributions of each automotive body panel. Discontinuous IGABEM is more… More >

Yi Wu, Zhuojia Fu^*, Jian Min

CMES-Computer Modeling in Engineering & Sciences, Vol.135, No.1, pp. 377-393, 2023, DOI:10.32604/cmes.2022.023205

Abstract This paper proposes a modified formulation of the singular boundary method (SBM) by introducing the combined Helmholtz integral equation formulation (CHIEF) and the self-regularization technique to exterior acoustics. In the SBM, the concept of the origin intensity factor (OIF) is introduced to avoid the singularities of the fundamental solutions. The SBM belongs to the meshless boundary collocation methods. The additional use of the CHIEF scheme and the self-regularization technique in the SBM guarantees the unique solution of the exterior acoustics accurately and efficiently. Consequently, by using the SBM coupled with the CHIEF scheme and the self-regularization technique, the accuracy of… More >

Jacob Thottathil Varghese^1,2,*, Sajan Thomas^1,2,3, Joselin Herbert⁴, Chacko Preno Koshy^1,2, Arjun Venugopal^1,2

Sound & Vibration, Vol.56, No.3, pp. 255-274, 2022, DOI:10.32604/sv.2022.016180

Abstract The arrangement of natural and physical features on the earth’s surface are a few among the countless items that govern the airborne acoustic transmission at boundary layers. In particular, if the acoustic waves are attributes of live concerts at open-air theatres, without losing the sheen and quality, the audience should certainly receive the unbroken depth of the performance. Hence, at all times, it is advisable to analyse the auditory receptiveness, particularly in all intended recreational spaces. The current pandemic circumstances and the mandated COVID-19 prevention protocols encourage gatherings in naturally ventilated outdoor regions than confined indoors. This work predicts and… More >

Si Chen¹, Yuhao Zhou¹, Sarah Mohrmann², Haiyan Fu¹, Yuying Zou¹, Zheng Wang^1,*

Journal of Renewable Materials, Vol.10, No.11, pp. 2791-2803, 2022, DOI:10.32604/jrm.2022.021531

Abstract Based on the efficient sound absorption characteristics of Helmholtz resonance structures in the range of medium and low frequency acoustic waves, this paper investigates an effective solution for light timber construction walls with acoustic problems. This study takes the light timber construction wall structure as the research object. Based on the Helmholtz resonance principle, the structure design of the wall unit, impedance tube experiment and COMSOL MULTIPHYSICS simulation calculation were carried out to obtain the change rule of acoustic performance of the Helmholtz resonance wall unit structure. The research results show that the overall stability of sound insulation of the… More > Graphic Abstract

Ajinkya S. Umbarkar^1,*, Deoram V. Nandanwar¹, Omprakash P. Chimankar²

Sound & Vibration, Vol.56, No.2, pp. 193-203, 2022, DOI:10.32604/sv.2022.015322

Abstract Here we report first ever study on acoustical evaluation of Kanheri Caves located in Sanjay Gandhi National Park, Mumbai (Maharashtra, India). These caves are dated to a period between 2^nd century BCE to 7^th century CE. In this study we used an ambisonic recorder to capture Impulse Response, which carries acoustic signature of the place. Out of total 109 caves 41 were surveyed in available time. Out of those reverberant environment was noted in 12 caves. Measurements were made only in 3 caves (Cave Nos. 1, 3, 11) which are important. In the beginning we carried out an FFT analysis.… More >

Vignesh Sekar^1,*, Se Yong Eh Noum¹, Azma Putra², Sivakumar Sivanesan¹, Kok Chun Chin¹, Yi San Wong¹, Dg Hafizah Kassim³

Sound & Vibration, Vol.55, No.4, pp. 343-352, 2021, DOI:10.32604/sv.2021.014916

Abstract This paper presents the development and performance of micro-perforated panels (MPP) from natural fiber reinforced composites. The MPP is made of Polylactic Acid (PLA) reinforced with Oil Palm Empty Fruit Bunch Fiber (OPEFBF). The investigation was made by varying the fiber density, air gap, and perforation ratio to observe the effect on the Sound Absorption Coefficient (SAC) through the experiment in an impedance tube. It is found that the peak level of SAC is not affected, but the peak frequency shifts to lower frequency when the fiber density is increased. This phenomenon might be due to the presence of porosity… More >

Al Munawir¹, Azma Putra^2,*, Iwan Prasetiyo³, Wan Mohd Farid Wan Mohamad², Safarudin Herawan⁴

Sound & Vibration, Vol.55, No.3, pp. 203-219, 2021, DOI:10.32604/sv.2021.015938

Abstract Statistical Energy Analysis (SEA) is a well-known method to analyze the flow of acoustic and vibration energy in a complex structure. This study investigates the application of the corrected SEA model in a non-reverberant acoustic space where the direct field component from the sound source dominates the total sound field rather than a diffuse field in a reverberant space which the classical SEA model assumption is based on. A corrected SEA model is proposed where the direct field component in the energy is removed and the power injected in the subsystem considers only the remaining power after the loss at… More >