Parametric Study of Porous Sound Absorbing Materials Using Taguchi method – Term Paper Example

The paper “Parametric Study of Porous Sound Absorbing Materials Using Taguchi method" is a great variant of a term paper on physics. Porous materials are widely used in many vibroacoustic applications. Different available models describe their behaviors according to material physical properties. For instance, in the case of porous materials with a rigid frame, and according to the Johnson-Champoux-Allard model, five parameters are employed. In this paper, an investigation about this model sensitivity to parameters according to frequency is conducted. Taguchi method is used for the sensitivity analysis. A strong parametric frequency-dependent hierarchy is shown. Sensitivity investigations confirm that airflow resistivity is the most influent parameter when acoustic sound absorption of porous materials is considered. The analysis first performed on a wide range of porous materials and then restricted to Poly felt fiber analysis in order to illustrate the impact of the reduction of the design space.

Introduction
Sound-absorbing material absorbs most of the sound energy striking them and reflect little. By so doing they reduce the noise (Allard, 2009. pp 874). The existing material uses frequency, composition, thickness, surface finish and method of mounting. But according to research the material that has a high value of sound-absorbing co-efficient are usually porous. By definition, the porous material is solids that contain cavities, channels, or interstices so that sound waves are able to enter through them. They are categorized by the availability of an external fluid such as air to pass through them. Their effect extends to as much as the bulk density, mechanical strength and thermal conductivity (Crocker, 2008. pp 696). By contradiction, closed pores are substantially less efficient than open pores in absorbing sound waves. Open-pore can beside to be blind to mean they are only opened on one side only. Classical classification of porous material can be cellular, fibrous, or granular basing on their microscopic configurations. They are characterized by the fact their surface allows sound waves to enter the material through a multitude of small holes or opening (Lanoye, R. et al., 2006. pp 2826). Most current application of sound reduction technique now employs Taguchi methods where the application of sound dissipation by sound-absorbing material rather than sound absorption or sound transmission phenomenon. This in finality, meets the requirement of high-efficiency low-weight material that does not lead to an unnecessary increase in the weight of the vehicle (Ghani, 2002. pp 84).  Sensitivity analysis of the five parameters
Sensitivity analysis has been done on the porous material and how they work out. The following five aspects were brought into the fore in the process of the analysis of the parameters. They include one, the porosity of the material-this has a minute effect on the features of interest. The only peculiarity is that it has a better lower threshold of 800Hz for the imaginary parts of impedance where all the frequency is captured regardless of quality of the frequency, two is the flow resistivity which is considered globally as the most sensitive parameter for each future and the entire frequency range (Garg, 2004. pp 1406).

Another in that line according to Aydin, H. et al., (2010), is the tortuosity of the porous material and for this parameter is considered as being with limited impact on acoustic performance with exception of frequency over a 1000 Hz but the good aspect is that it has coupling effect between tortuosity, thermal characteristic length finally the vicious characteristic length of the porous material which is said to be irrelevant with sound frequencies that are below 500 Hz (Unal, 2013. pp 630). These five parameters are the one that is used in determining the sensitivity of the porous material in sound absorbency.

Advantage of Taguchi method
The method has a clear guideline on how to follow to pursue the sensitivity analysis. It has an allowance of using small set from all the possibility selected and end producing most information which is known as partial fraction level is contained in the Taguchi method which makes the analysis highly effectual (Aydin, 2010. pp 205). According to Hong (2012), it also follows special set of general design guideline for factorial experiments for the factorial experiment that cover much application at ago. More so it uses a set of array called orthogonal arrays which stipulate a way of conducting the minimal number of experiment. Another advantage is that the additive individual or main effect of the independent variables on performance parameter are assumed to be separable (Shravage, 2010. pp 1735).