Measurement and Inverse Estimation of the Full Anisotropic Flow Resistivity Tensor of Glass Wool (original) (raw)
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Measurement and Inverse Estimation of the Full Anisotropic Flow Resistivity Tensor of Melamine Foam
The flow resistivity tensor, which is the inverse of the viscous permeability tensor, is one of the most important material properties for the acoustic performance of open cell foams used in acoustic treatments. Due to the manufacturing processes, these foams are most often geometrically anisotropic on a microscopic scale. For such a materials there is a need for improved characterisation methods, and this paper discusses the estimation of the flow resistivity tensor of Melamine samples using a methodology which is an improvement of a method previously published by Göransson et al. The validity of the new method is verified for a wider range of anisotropy. Measurements are performed on seven cubic Melamine samples, and the resulting 3D flow resistivity tensors are presented. The anisotropic flow resistivity tensors are validated by comparison to measurements performed on uni-directional cylindrical samples extracted from the previously measured cubic samples. The results suggest tha...
In-Plane Permeability Measurement of Biaxial Woven Fabrics by 2D-Radial Flow Method
Science and Engineering of Composite Materials, 2021
The accurate characterization of fabrics used in vacuum assisted resin transfer molding (VARTM) is essential in order to model the flow through these porous preforms. A wide range of these fabrics are available for composite manufacturing through VARTM and thus brings about a need to opt a methodology which characterizes the in-plane permeability of these preforms. These permeability values can then be used in simulations that can track the flow front progression and mold filling time. This work identifies the permeability of an E-glass fabric based on Darcy's law. Woven fabric having areal weight of 200 grams per square meter (gsm) is under consideration. The experiments are conducted at constant pressure conditions using 2D Radial flow method. Stereo microscopy of the preform material is done for detailed study of the weaving pattern. It is concluded that plain woven fabric exhibits anisotropic behavior when tested for in-plane permeability. Permeability is found to be higher ...
The flow resistivity tensor, which is the inverse of the viscous permeability tensor, is one of the most important material properties for the acoustic performance of open cell foams, used in acoustic treatments. Due to the manufacturing processes, these foams are most often geometrically anisotropic. This paper discusses the estimation of the flow resistivity tensor using an improvement of a previously published method by Göransson, Guastavino et al. First, flow measurements were performed for different orientations of a cubic porous sample. The modelling of the flow resistivity tensor is centred around a three-dimensional Darcy's law model in COMSOL Earth Science Module, representing the experimental set up. The simulations are performed within an optimisation loop, to determine which flow resistivity tensor gives the best fit of the simulation results to the experimental data, of volume flow and pressure drop between the inlets and outlets. The discussion focuses on the optim...
A European Inter-Laboratory Test of Airflow Resistivity Measurements
Acta Acustica united with Acustica
This article presents and analyses the results of an Inter-Laboratory Test (ILT) of airflow resistivity measurements according to the ISO 9053 standard. The main result of the ILT is the determination of the repeatability and reproducibility standard deviation values typical of these measurements, for the first time since the ISO 9053 publication in 1991. Ten European laboratories took part in the ILT project; two melamine foam sheets of different thickness, taken from the same factory batch, were sent to each laboratory. The laboratories cut the test samples and carried out measurements in repeatability conditions, either on a single sample either on different samples, in order to take into account also the influence of the sample cutting and non-homogeneity of the foam. The data show that most of the laboratories have a good internal repeatability, particularly for single sample measurements. The overall reproducibility is not so good, mainly due to systematic deviations inherent ...
International Journal of Engineering & Technology
The thermal energy of building is determined by the thermal properties of the materials and how to install these materials in the elements of buildings according to the direction of heat transfer. The effectiveness of thermal insulation (glass wool) is dependent on its thermal conductivity which is varies in different directions of fibers of glass wool. Glass wool is formed of fibers and binders tangled together during the industrial process to provide some elasticity. The experimental values of thermal conductivity of the insulation materials are changed according to magnitude of the heat power and direction of fiber arrangement. The thermal conductivity for insulation materials has been measured by using probe method, Huekseflux ® TP02 used to measure the thermal conductivity by emit the flow perpendicular and parallel to the fibers of glass wool. Two samples of yellow glass wool (density 68 kg/m3) with dimensions (10 ×10 ×30) cm have been used. Hot Disk bulk isotropic module has...