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Polymers utilised in construction
Published in Ash Ahmed, John Sturges, Materials Science in Construction: An Introduction, 2014
Melamine foam has an interlinking bubble format which produces a structure more like a block of microscopic fibreglass than normal foam. It can also be used for soundproofing and as a fire-retardant material, but not as insulation because it allows air to pass through its structure.
The effect of rail shields on railway rolling noise
Published in International Journal of Rail Transportation, 2023
Xianying Zhang, David Thompson, Jungsoo Ryue, Hongseok Jeong, Giacomo Squicciarini
In the model, the rail vibration is again calculated when it is continuously supported on a layer of elements representing the rail pads; rail and rail pads are modelled using solid finite elements as before. The rail pads are not shown in Figure 3 but are superimposed on the porous material beneath the rail foot. The shield is modelled by using a continuous plate reaching from the rail web to the underside of the foot. Its upper edge is mechanically coupled to the rail web in translation (vertically and laterally) but is allowed to rotate freely at the connection point. The air inside the shield is represented by using acoustic finite elements. The maximum element size in the fluid region is 2 cm which gives five node points per acoustic wavelength at the maximum frequency. The shaded elements shown correspond to the poro-elastic material. This extends beneath the rail foot as well as being located on the sides of the shield. It is dynamically coupled to both the rail foot and the shield, and is assumed to co-exist with the rail pad. The properties used for this porous material correspond to a typical melamine foam [32] and are listed in Table 2.
Analysis of Fluid Flow and Heat Transfer in Corrugated Porous Fin Heat Sinks
Published in Heat Transfer Engineering, 2021
Shripad A. Upalkar, Sanjeet Kumar, Shankar Krishnan
The cross-section of the duct is 50 mm × 45 mm. The size of the melamine foam sample was 50 mm × 50 mm × 6 mm. The conduit has a width of 19.5 mm, whereas the length and height both are 50 mm. This foam sample was fitted in the test chamber of the airflow duct. The melamine foam was kept at the center of the flow duct, and the thin acrylic sheets were attached to it on both ends to form a Z-type arrangement for fluid flow. During the experimentation, the flow rate was varied using a Yaskawa V1000 variable frequency drive in conjunction with a counter-blower. The flow rate was varied from 0.0011 m3/s to 0.0041 m3/s. As the least count of the U-tube manometer is 1 mm, the uncertainty in measuring pressure drop is ±5 N/m2. The pressure drop across the array of nozzles in the flow chamber, which is used to calculate flow rate (and in turn, the flow velocity), is measured using an inclined manometer whose least count was 0.01 inch and corresponding uncertainty in pressure drop measurement is ±1.25 N/m2 (0.01 inch of water ≈ 2.5 N/m2).
Vibroacoustic analysis of an innovative windowless cabin with metamaterial trim panels in regional turboprops
Published in Mechanics of Advanced Materials and Structures, 2021
M. C. Moruzzi, M. Cinefra, S. Bagassi
The chosen metamaterial is a melamine foam with cylindrical inclusions of aluminum with volume fraction of 0.015. Its frequency dependent properties are reported in Table 2. The advantages of using melamine (formaldehyde-melamine-sodium bi-sulfite copolymer) are high sound absorption capacity, low weight, good thermal insulation properties, and flexibility at very low temperature; moreover, this material is fireproof. Aluminum is used because of its proven efficiency in aeronautics. The total density of this metamaterial is very similar to the density of Nomex: 48.38 for the metamaterial instead of 48.00 for the Nomex. The two fiberglass plates and the thickness of the core remain the same.