This study quantified the microstructure of polyurethane foams and elucidated its relationship to fluid-acoustic parameters. The complex morphology derived from the three-dimensional images obtained by micro-computed tomography was analyzed using digital image processing and represented by a pore network model (PNM) and a distance map model. The PNM describes the fluid phase of a porous medium with equivalent spherical pores and circular throats, whereas the distance map model describes the solid phase with the average frame thickness. The porous materials were then modeled by six representative microstructural parameters that describe the geometry and topology of the fluid and solid phases. These parameters were pore radius, throat radius, distance between adjacent pores, coordination number, pore inclination angle, and frame thickness. Semi-phenomenological and empirical approaches were proposed to relate the microstructural properties to the fluid-acoustic parameters. These models effectively described the acoustic parameters and sound absorption performance of six different polyurethane foams. Since the representative microstructural parameters were obtained from small sample volumes of a heterogeneous material, notable variations were observed across different regions of the sample. Hence, this study quantified the effect of the uncertainty in each microstructural parameter on the resulting acoustic parameters using global sensitivity analysis.

中文翻译：

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利用微结构特性估算和分析多孔材料的流体声学参数。

这项研究量化了聚氨酯泡沫的微观结构，并阐明了其与流体声学参数的关系。使用数字图像处理技术分析了通过微计算机断层扫描获得的三维图像的复杂形态，并以孔网模型（PNM）和距离图模型表示。PNM描述了具有等效球形孔和圆喉的多孔介质的流体相，而距离图模型描述了具有平均框架厚度的固相。然后通过描述流体和固相的几何形状和拓扑结构的六个代表性微结构参数对多孔材料进行建模。这些参数是孔半径，喉部半径，相邻孔之间的距离，配位数，孔倾角和镜架厚度。提出了半现象学和经验方法，以将微观结构特性与流体声学参数联系起来。这些模型有效地描述了六种不同聚氨酯泡沫的声学参数和吸声性能。由于代表性的微结构参数是从少量异质材料的样品中获得的，因此在样品的不同区域观察到明显的变化。因此，本研究使用全局灵敏度分析量化了每个微结构参数的不确定性对所得声学参数的影响。这些模型有效地描述了六种不同聚氨酯泡沫的声学参数和吸声性能。由于代表性的微结构参数是从少量异质材料的样品中获得的，因此在样品的不同区域观察到明显的变化。因此，本研究使用全局灵敏度分析量化了每个微结构参数的不确定性对所得声学参数的影响。这些模型有效地描述了六种不同聚氨酯泡沫的声学参数和吸声性能。由于代表性的微结构参数是从少量异质材料的样品中获得的，因此在样品的不同区域观察到明显的变化。因此，本研究使用全局灵敏度分析量化了每个微结构参数的不确定性对所得声学参数的影响。