Study On RTM Molding Process Of Skin Of The Wing Composite Scale Model

In order to provide aerodynamic data which is required for the aircraft design process,the aerodynamic performance of the aircraft is predicted by making wing scale model in aircraft development process.In this paper,the composite scale model of wing which has been studied is consist of the spar,wing rib,skin,attachment etc.The traditional forming process is manufacturing skin by hand lay-up process in the mold,and skin,the spar,wing rib,foam-filled,and other glue together during mold clamping process.The process,which is inefficiency and of poor quality,will volatilize gas which is harmful to workers and the environment.Resin transfer molding(RTM)process is a kind of closed mold forming process.Resin transfer molding(RTM)process not only overcomes the above shortcomings of the traditional process,but also have some advantages,such as high dimensional accuracy of the product,achieving the integral molding of complex structure,products with high fiber content and low porosity.Thus the skin of wing composite scale model is gradually formed by RTM process.The design and fabrication of mold and skeleton,the determination of injection scheme needs to investigate,which makes important significance for skin of wing composite scale model is formed by RTM molding process.In this paper,the influence law of permeability change caused by the uneven fiber volume density on the resin flow front has been investigated.Effects of the local permeability on the flow front and the time of resin filling the local region have been respectively simulated with the commercial software RTM-Worx,respectively.For further verification,the corresponding experiments are designed.In the verification experiments,spacers with different thicknesses have been adopted to change the local fiber volume density.And good agreements between the simulated and the experimental results can be observed.Both simulation and experimental results show that the time of resin filling the local region increases sharply when the local fiber volume density increases to a certain value and if the volume density continues increasing,the region will appear incomplete resin filling resulting in the phenomena of the final parts with dry spot defects.The shape and size of the non-uniform area of the fiber density in the local area have a great influence on the shape of the infiltration zone.In this paper,the RTM process of the wing composite scale model has been investigated through the design of the mold and sealing scheme,the design and manufacture of the skeleton,and determination of the injection scheme.Finally,skin of the wing composite scale model has been successfully formed by constant pressure injection of RTM molding process.And the deviation of the resin flow front between the RTM forming and the simulated can be analyzed and illustrated.The results show that in order to avoid the effect of permeability irregularity on the resin flow front,the machining errors of the skeleton and foam-filled should be controlled within a reasonable range.