A generalized compliance model for study of acoustic damping behavior of mixed porosity segmented perforated liner

2021 ◽  
Vol 183 ◽  
pp. 108302
Author(s):  
Ashutosh Tripathi ◽  
N.K. Jha ◽  
R.N. Hota
Author(s):  
Mohammad Al-Bsheish ◽  
Mu’taman Jarrar ◽  
Amanda Scarbrough

The outbreak of COVID-19 has placed a heavy burden on society, threatening the future of the entire world as the pandemic has hit health systems and economic sectors hard. Where time moves fast, continuing curfews and lockdown is impossible. This paper assembles three main safety behaviors, social distancing, wearing a facemask, and hygiene in one model (PSC Triangle) to be practiced by the public. Integrating public safety compliance with these behaviors is the main recommendation to slow the spread of COVID-19. Although some concerns and challenges face these practices, the shifting of public behaviors to be more safety-centered is appropriate and available as an urgent desire exists to return to normal life on the one hand and the medical effort to find effective cure or vaccine that has not yet succeeded on the other hand. Recommendations to enhance public safety compliance are provided.


2021 ◽  
Vol 23 (3) ◽  
Author(s):  
Niklas Meyer ◽  
Robert Seifried

AbstractParticle damping is a promising damping technique for a variety of technical applications. However, their non-linear behavior and multitude of influence parameters, hinder currently its wide practical use. So far, most researchers focus either on determining the energy dissipation inside the damper or on the overall damping behavior when coupled to a structure. Indeed, currently almost no knowledge exchange between both approaches occurs. Here, a bridge is build to combine both techniques for systems under forced vibrations by coupling the energy dissipation field and effective particle mass field of a particle damper with a reduced model of a vibrating structure. Thus, the overall damping of the structure is estimated very quickly. This combination of both techniques is essential for an overall efficient dimensioning process and also provides a deeper understanding of the dynamical processes. The accuracy of the proposed coupling method is demonstrated via a simple application example. Hereby, the energy dissipation and effective mass of the particle damper are analyzed for a large excitation range first using a shaker setup. The particle damper exhibits multiple areas of different efficiency. The underlying structure is modeled using FEM and modal reduction techniques. By coupling both parts it is shown that multiple eigenmodes of the structure are highly damped using the particle damper. The damping prediction using the developed coupling procedure is validated via experiments of the overall structure with particle damper.


2011 ◽  
Vol 66-68 ◽  
pp. 1155-1162
Author(s):  
Jian Ning Wei ◽  
Gen Mei Li ◽  
Li Ling Zhou ◽  
Xue Yun Zhou ◽  
Jian Min Yu ◽  
...  

A large number of macroscopic pores were introduced into commercially pure aluminum (Al) and Zn-Al eutectoid alloy by air pressure infiltration process to comparatively study the influence of macroscopic pores on the damping behaviors of the materials. Macroscopic pores size are on the order of a millimetre (0.5~1.4mm) and in large proportions, typically high 76vol.%. The damping behavior of the materials is characterized by internal friction (IF). The IF was measured on a multifunction internal friction apparatus (MFIFA) at frequencies of 0.5, 1.0 and 3.0 Hz over the temperature range of 25 to 400 °C, while continuously changing temperature. The damping capacity of the metal materials is shown to increase with introducing macroscopic pores. Finally, the operative damping mechanisms in the metal materials with macroscopic pores were discussed in light of IF measurements.


2011 ◽  
Vol 24 (2) ◽  
pp. 143-148 ◽  
Author(s):  
Pascal Magne ◽  
Michael Silva ◽  
Elisa Oderich ◽  
Luis Leonildo Boff ◽  
Reyes Enciso
Keyword(s):  

2006 ◽  
Vol 9 (2) ◽  
pp. 193-197 ◽  
Author(s):  
Luiz Cláudio Pardini ◽  
Flaminio Levy Neto ◽  
Jorge Luiz de Almeida Fereira

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