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The Behavior of Structures Composed of Composite Materials Part 2

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Tham khảo tài liệu 'the behavior of structures composed of composite materials part 2', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 19 1.5.10 AUTOCLAVE MOLDING Autoclave molding is a further modification of either vacuum bag or pressure bag molding. The process produces denser void-free composites because higher heat and pressure are used in the cure. Autoclaves Figure 1.14 are essentially heated pressure vessels usually equipped with vacuum systems into which bagged lay-ups on their molds are taken to be cured at pressure of 50 to 100 psi. Autoclaves are normally used to process high-performance components based on epoxy-resin systems for aircraft and aerospace applications. FIGURE 1.14. Autoclave 1.5.11 FILAMENT WINDING Some FRP production methods involve specialized approaches to making parts requiring unusual properties or configurations such as very large size extremely high strength highly directional fiber orientation unusual shape or constant cross section. In most cases these methods are the only ones suitable for the conditions of configurations for which they were designed. Continuous resin-impregnated fibers or roving are wound on a rotating mandrel in a predetermined pattern providing maximum control over fiber placement and uniformity of structure. See Figure 1.15. In the wet method the fiber picks up the low viscosity resin either by passing through a trough or from a metered application system. In the dry method the reinforcement is impregnated with resin prior to winding. Integral fittings and vessel closings can be wound into the structure. When sufficient layers have been applied the FRP composite is cured on the mandrel and the mandrel is removed. Filament winding is traditionally used to produce cylindrical and spherical FRP products such as chemical and fuel storage tanks and pipe pressure vessels and rocket 20 motor cases. However the technology has been expanded and with computer controlled winding machines other shapes are now being made. Today computerized numerical control can provide up to 11 axes of motion for single and multiple spindles. Examples are helicopter .