Frequency Response Function for Prediction of Planar Cellular Plastic Foam                 Acoustic Behavior

Tsay, Huoy-Shyi; Yeh, Fung-Huei

doi:10.1177/0021955x05051737

Cited by 10 publications

(19 citation statements)

References 25 publications

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“…It is noted that all stresses Optimal Design of Corrugated Cellular Plastic Foam are zero at t ¼ 0, if the foam is stress free at the initial state. According to the Biot's poroelastic theory and the Cartesian coordinates defined, the dynamic equations for the cellular plastic foam after the Laplace transform with respect to the time variable t can be written [8] as:…”

Section: Finite Element Frequency Domain Acoustic Analysismentioning

confidence: 99%

Optimal Design of Corrugated Cellular Plastic Foam with Semi-elliptical Shaped Upper Surface by Finite Element Frequency Domain Acoustic Analysis

Tsay

Yeh

2007

Journal of Cellular Plastics

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A general way to enhance the sound absorption capability of cellular plastic foam is the use of corrugated foam. The corrugated surface can greatly enhance the sound absorption of the foam in the mid and high frequency ranges. In this study, a finite element frequency domain acoustic analysis is used for the analysis. Such a numerical method is more efficient than the methods used in earlier studies as it saves the calculation time on the elements of the incident acoustic field. During the optimal design of the corrugated cellular plastic foam with semi-elliptical shaped upper surface, the cross-sectional width (the length of the minor axis) and the area of one section of the corrugated foam are kept the same throughout the study. The variation of the semi-elliptical shape is performed by changing the length of the semi-major axis. By varying the length of the semi-major axis, the maximum sound absorption capability of the semi-elliptical shaped corrugated foam is found. It is concluded that in the high frequency region (2000-4000 Hz), the foam with the major axis to the crosssectional width ratio (MWR) of 1.96 has the maximum sound absorption capability and its broadband averaged normal incidence sound absorption coefficient is improved from 0.882 to 0.945.

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Section: Finite Element Frequency Domain Acoustic Analysismentioning

confidence: 99%

Optimal Design of Corrugated Cellular Plastic Foam with Semi-elliptical Shaped Upper Surface by Finite Element Frequency Domain Acoustic Analysis

Tsay

Yeh

2007

Journal of Cellular Plastics

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“…͑1͒ and ͑2͒ can all be related to the foam constituents, the mass density of solid s , the mass density of fluid f , porosity , tortuosity ␣ ϱ , pore cross-section shape correction factor c, and DC flow resistivity 0 . The typical material properties of the polyurethane foam saturated with air are summarized by Tsay and Yeh 13 and presented as follows.…”

Section: Materials Properties Of Polyurethane Foammentioning

confidence: 99%

“…The two-microphone acoustic measurement system used for the earlier study 13 was applied for measuring the acoustical properties of foam samples. The measurement system was established according to the ASTM E1050-98 standard.…”

Section: Measurement Systemmentioning

confidence: 99%

“…13 Commonly, the acoustical properties of the sound absorption material with complex geometry are numerically pursued by applying the porous model coupled by an incident acoustic field with which the sound absorption material is in contact. The transmission and reflection waves that characterized acoustical properties are then solved.…”

Section: Introductionmentioning

confidence: 99%

“…Upon obtaining the dynamic transfer function, frequency response functions of the sample representing the dynamic stiffness, surface impedance, reflection, and absorption coefficients in the frequency domain can be obtained by simply replacing the Laplace transform parameter s by j where is the radial frequency. 13,24,25 Subsequently, with the use of the roller circumferential edge constraint, the acoustical properties of a planar, laterally infinite, and rigidly backed open-cell polyurethane foam with permeable upper surface are validated first. Then, the influences of the fixed circumferential edge constraint and the diameter-to-thickness ratio on the acoustical properties of polyurethane foam samples are examined.…”

Section: Introductionmentioning

confidence: 99%

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The influence of circumferential edge constraint on the acoustical properties of open-cell polyurethane foam samples

Tsay

Yeh

2006

The Journal of the Acoustical Society of America

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In this paper, a three-dimensional Laplace domain finite element model with four-node tetrahedral porous elements is developed and applied for the investigations. Without the incident acoustic field, the exact acoustical properties of a laterally infinite planar foam, which is backed with a rigid plane, are accurately predicted by assuming the circumferential edge constraints as rollers. It is found that the rigidity of the circumferential edge constraint has a profound effect on the predictions. If the circumferential edge constraints are all fixed, the amplitude of the first sound absorption peak is increased, and the peak is moved to a lower frequency as compared with the exact solutions. Measurements obtained by the two-microphone impedance tube method are bounded by the predictions of samples with roller as well as with fixed constraints. They are much closer to that predicted with fixed edge constraints. Upon increasing the diameter-to-thickness ratio of the sample, the influence of the fixed edge constraint is reduced. The measured acoustic results can be the representatives of the laterally infinite planar foam from which the sample was cut only if the roller edge constraint of the sample is managed or the diameter-to-thickness ratio of the sample is increased.

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Mechanical and acoustic performance of compression‐molded open‐cell polypropylene foams

McRae

Naguib

Atalla

2009

J of Applied Polymer Sci

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Open‐cell materials are lightweight and multifunctional capable of absorbing acoustic energy and supporting mechanical load. The acoustic and mechanical performance of open‐cell materials can be optimized through processing. In this article, the relationships between processing parameters and acoustic and mechanical performance are shown for polypropylene (PP) foams. PP foam samples are fabricated using a combined compression molding and particulate leaching process. The results from a parametric study showed that both salt size and salt to polymer ratio affect the acoustic and mechanical performance of open‐cell PP foams. As salt size increases, cell size increased and cell density decreased. The salt to polymer ratio had opposite affect on cell density, and increasing the salt to polymer mass ratio increased the open‐cell content. The airflow resistivity decreased significantly by increasing the cell size, which means that foam samples with smaller cell size have better sound absorption. When foam samples were thin, smaller cell sizes produced better sound absorption; however, as thickness of the sample increases, medium cell size offered the best acoustic performance. The compressive strength of the foams was increased by increasing the relative density. Acoustic performance results from the parametric study were compared to the Johnson‐Allard model with good agreement. Finally, optimal cellular morphologies for acoustic absorption and mechanical performance were identified. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

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Frequency Response Function for Prediction of Planar Cellular Plastic Foam Acoustic Behavior

Cited by 10 publications

References 25 publications

Optimal Design of Corrugated Cellular Plastic Foam with Semi-elliptical Shaped Upper Surface by Finite Element Frequency Domain Acoustic Analysis

Optimal Design of Corrugated Cellular Plastic Foam with Semi-elliptical Shaped Upper Surface by Finite Element Frequency Domain Acoustic Analysis

The influence of circumferential edge constraint on the acoustical properties of open-cell polyurethane foam samples

Mechanical and acoustic performance of compression‐molded open‐cell polypropylene foams

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