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

Parametric study of porous sound absorbing materials using Taguchi method ABSTRACT

Porous materials are widely used in many vibroacoustic applications. Different available models describe their behaviours according to material physical properties. For instance, in the case of porous materials with 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 are 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 wide range of porous materials and then restricted to Polyfelt fibre analysis in order to illustrate the impact of the reduction of the design space.
Introduction
Sound-absorbing material absorb 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 have a high value of sound absorbing co-efficient are usually porous. By definition porous material are 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 extend 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 be side 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 characterised by the fact their surface allow 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 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 do not lead to unnecessary increase in 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 aspect 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 are used in determining the sensitivity of the porous material in sound absorbency.
Advantage of Taguchi method
The method has clear guide line on how to follow to pursue the sensitivity analysis. It has 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 follow special set of general design guideline for factorial experiments for the factorial experiment that cover many 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).

References
Allard, J.F. & Atalla, N., 2009. Propagation of Sound in Porous Media: Modelling Sound Absorbing Materials. pp. 874.
Aydin, H. et al., 2010. Application of Grey Relation Analysis (Gra) and Taguchi Method for the Parametric Optimization of Friction Stir Welding (Fsw) Process. Materiali in Tehnologije, 44, pp.205–211.
Crocker, M.J. & Arenas, J.P., 2008. Use of Sound-Absorbing Materials. In Handbook of Noise and Vibration Control. pp. 696–713.
Garg, N., Kumar, A. & Maji, S., 2013. Parametric sensitivity analysis of factors affecting sound insulation of double glazing using Taguchi method. Applied Acoustics, 74, pp.1406–1413.
Ghani, J.A., Choudhury, I.A. & Hassan, H.H., 2004. Application of Taguchi method in the optimization of end milling parameters. Journal of Materials Processing Technology, 145, pp.84–92.
Hong, C.-W., 2012. Using the Taguchi method for effective market segmentation. Expert Systems with Applications, 39, pp.5451–5459.
Lanoye, R. et al., 2006. Measuring the free field acoustic impedance and absorption coefficient of sound absorbing materials with a combined particle velocity-pressure sensor. The Journal of the Acoustical Society of America, 119, p.2826.
Rumpler, R., Deü, J.-F. & Göransson, P., 2012. A modal-based reduction method for sound absorbing porous materials in poro-acoustic finite element models. The Journal of the Acoustical Society of America, 132, pp.3162–79.
Shravage, P., Jain, S. & Karanth, N., 2010. Effect of intrinsic parameters on sound absorption and transmission loss: A parametric study. The Journal of the Acoustical Society of America, 127, p.1735.
Unal, R., Stanley, D.O. & Joyner, C.R., 2013. Propulsion system design optimization using the Taguchi method. IEEE Transactions on Engineering Management, 40.pp.630.