Volume fraction

About: Volume fraction is a research topic. Over the lifetime, 16312 publications have been published within this topic receiving 374181 citations.

Microstructure and tensile properties of 2014 Al alloy reinforced with continuous carbon fibers manufactured by gas pressure infiltration

Abstract: Gas pressure infiltration method was used to prepare a composite consisting of unidirectional Ni-coated carbon fibers (C f ) in 2014 Al alloy matrix. The microstructure of the composite produced showed a full infiltration of molten aluminum alloy and evenly distributed fibers with a volume fraction of 30 vol%. Also, there was no sign of fiber clusters or residual porosity. The fiber–matrix interface was smooth with no discontinuities. Energy dispersive X-ray analysis (EDXA) results of the composite microstructure revealed no sign of significant reaction at the interface between the fibers and aluminum matrix alloy. Compared to the aluminum matrix alloy, the composite exhibited significant increases in modulus and ultimate tensile strength. However, the elongation to failure of the composite was considerably reduced. Moreover, the tensile modulus and ultimate tensile strength were in good agreement with the values predicted by the simple rule of mixture due to the strong interfacial bonding and absence of fiber strength degradation during composite preparation. SEM micrographs of the composite fracture surface showed that fracture took place mainly in the relatively weak aluminum alloy matrix, in comparison to the interfacial and fiber strengths, by void nucleation, growth, and shearing of the fibers.

The permeability and compressibility of aligned and cross‐plied carbon fiber beds during processing of composites

Abstract: Two of the most important input parameters needed to simulate the processing of continuous fiber laminated composites are the fiber bed permeability and the portion of the autoclave load borne by the consolidating fiber network (compressibility). In this study we have experimentally examined how both these parameter change with resin volume fraction as pressure is applied and consolidation proceeds. For a unidirectional fiber bed, the Kozeny-Carman equation can be used to predict both the transverse (perpendicular to the laminate plies) permeability (Kozeny constant, K′z = 11) and the axial (parallel to the fibers) permeability (Kozeny constant, K′X = 0.57). The axial permeability was found to be dependent on the surface tension of the permeant. For a unidirectionally aligned fiber, the measured transverse permeabilities varied from 1.1 × 10−10 cm2 to 12. × 10−9 cm2 while the axial values varied from 2.1 × 10−9 to 4.4 × 10−8 cm2 for a liquid volume fraction range of 0.25 to 0.5. Axial permeability measurements indicate that the permeability decreases with increasing off-axis angle × (measured from the laminate axial direction). The off-axis permeability behavior can be described by a modified Kozeny-Carman equation. The fiber network compressibility can be described with a logarithmic relation which has been found valid for a large number of consolidated soils.