Measurement And Analysis Of The Permeability Of 2.5D Woven Reinforcement Materials

As an advanced technology used to fabricate high performance fiber reinforced composites, resin transfer molding (RTM) process has been extensively applied in aircraft, aerospace and communication industries for its outstanding advantages, including low investment costs for equipment and tooling,relatively short cycle times with good production quality, slight pollution and the ability to manufacture large complex structures.The 2.5D wove structural composites is a recent development direction in the woven composites area. Along with the research of wove structural composite, the application of 2.5D wove structural composites has developed so rapidly that cause more recognition. Permeability is an inherent attribute of 2.5D woven reinforcement material to describing the obstruction of the material to resin flow. Measuring the permeability accurately is very important for mold optimizing design; mold filling simulation and production quality guarantee in RTM processing. Because the theory of permeability is still immature, the difference between analytic result and the actual permeability is obvious, moreover has the very big limitation. Therefore,the permeability of 2.5D woven reinforcement material was usually obtained by experiment in practice. Four kinds of 2.5D glass fiber woven reinforcement materials with different fibbers volume fraction were studied in this paper. According to RTM technique principle, permeability of the samples under the different mold filling parameters was measured using unidirectional flow and radial flow technique based on image processing. The result shows that permeability of 2.5D glass fiber woven reinforcement materials is anisotropic,and the orientation of the principal permeability is parallel to grain cross,moreover, volume fraction is a primary factor effecting the value of permeability。There are some factors affecting the permeability of fiber reinforcements such as inserting pressure, flowing velocity, characteristic of fluid, microcosmic structure of fibers, fibers volumetric content and structure of mold, etc. Clarifying the regulation of these parameters, which affect the permeability and design deeply, and ulteriorly controlling these factors always plays an important part in the production efficiency and the quality of manufacture. The regulation of the various parameters influences on the permeability of 2.5D woven reinforcement in RTM was studied such as fibers volume fraction, injecting pressure, fluid viscosity and mold width through the orthogonal experiment in this paper. The result indicated that along with fibers volume fraction increased, permeability value reduced rapidly; the injection pressure is also influenced obviously to the permeability, greater the injection pressure, increased the permeability value; the viscosity has weak influence to the permeability, the viscosity increases, the permeability has the tendency to increases, but not obvious; the mold width has the weakest influence on permeability.The study of this topic provided some objective basis for the design of processing parameter in RTM of 2.5D woven composite.