Filament Wound Structure

Its manufacturing is done by winding continuous strands of plastic-impregnated glass fiber around a steel mandrel at a precisely controlled helix angle, under controlled tension. A cross-sectional view of an RP layup is shown in Fig. 4-2(d). As seen, the structural wall of the pipe is made up of con- 

By now it should be apparent that, while both steel and RTR pipe are by definition flexible conduit, they are also quite different and therefore require different design approaches, even though initially at least then-design considerations are identical. As with steel pipe, the RTR pipe designer must concern oneself with both pipe deflection and buckling analysis. Unlike the steel pipe designer, however, the RTR pipe designer must also examine a third area of concern. 

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Filament-wound structures are often used to store fluid under pressure fuel storage tanks, rocket motor cases, natural gas, and oxygen storage tanks. In some cases, the filament-wound structure is subjected to external pressure a diving bell or submarine. Filament winding has... 

Filament-wound structures are typically cylindrical, spherical, or conical. In the case of cylindrical or conical shapes, there may be domed ends or specially wound flange ends. The fibers and resins can be selected from a wide variety of materials. These material and geometry options make filament winding a versatile manufacturing process. 

The function of the resin matrix material in filament-wound structures is to help distribute the load, maintain proper fiber position, control composite mechanical and chemical properties, and provide interlaminar shear strength. Either a thermosetting or a thermoplastic resin material may be selected. Thermosetting resins may be selected for application in a wetwinding process or as part of a prepreg resin system. 

For typical filament winding applications, the fiber reinforcement provides the stiffness and strength required to maintain structural integrity. Thus, material characterization for filament wound structures focuses on characterizing the fiber dominated stiffness and strength properties of the composite. The stiffness of fiber reinforced plastics (FRPs), in the fiber direction, is dominated by the fiber stiffness characteristics. The strength will be influenced by a number of factors, however, and not all of them are related to the fiber, including ... 

This section discusses test methods applicable to filament wound structures. As discussed earlier, filament wound structures are primarily subjected to internal and/or external pressure that is resisted by the fiber. Greater attention is therefore given to fiber-dominated stiffness/strength-dominated material characterization. 

There are numerous test methods that have been used to characterize the fiber-dominated composite strength and stiffness for filament wound structures. A number of these test methods have been standardized by the ASTM D30 Committee [39], These standardized tests methods include ... 

Srogress, samples of the matrix resins were removed and cast in 1-inch iameter cylindrical aluminum cups to form discs 1/8-inch thick. These were cured in the same oven with the filament-wound structures. The discs were then placed into distilled water contained in small beakers located in a room air conditioned to maintain 25°C. Periodically, the... 

Use Abrasive for cutting and grinding metals, grinding wheels, refractory in nonferrous metallurgy, ceramic industry and boiler furnaces, composite tubes for steam reforming operations. Fibrous form used in filament-wound structures and heat-resistant, high-strength composites. 

Properties of Composite Fiber/Matrix Systems. The volume fraction of fibers in most filament-wound structures and in laid-up composite layers can exceed 60 percent. For carbon fibers at this volume fraction, the composite has such a high absorption coefficient that it can be treated as opaque [251] however, for glass-epoxy composites, the absorption coefficient is small enough, particularly in some spectral windows, that radiation must be treated as a volumetric effect. The situation is complicated by the high fiber volume fraction, which causes the fiber absorption and scattering to be in the dependent regime however, some data are presented in Ref. 251. 

Table 5.11 Filament wound structures for commercial and industrial applications...

Table 5.12 Filament wound structures for aerospace, hydrospace, and military applications...

Minimum practical total RP thickness is established as 4.8 mm ( A6 in.) for the combined spray-up liquid seal and filament wound structural layers and 6.4 mm (V4 in.) for an all-chopped fiber spray-up laminate with sand filler. The choice for any construction is made on the basis of comparative design thickness, weight, and fabrication costs. The all-chopped fiber reinforced construction using somewhat greater wall thickness than the composite filament wound-chopped fiber wall is determined to provide the lowest tank cost filament winding provides lower weight. 

Uses Surfactant, curing agent, modifier for drying time in epoxy resins, composites, large filament wound structures, adhesives, injection repair compds., solv.-free coatings... 

Fiber placement In general, refers to how the piles are laid into their orientation, i.e., by hand, by a textile process, by a tape layer, or by a filament winder. Tolerances and angles are specified. Microprocessor-controlled placement that gives precise control of each axis of motion permits more intricate winding patterns than are possible with conventional winding and is used to make composites that are more complex that usual filament-wound structures. Tortora PG (ed) (1997) Fairchild s dictionary of textiles. Fairchild Books, New York. 

Netting analysis n. The stress analysis of filament-wound structures that neglects the strength of the resin and assumes that the filaments carry only axial tensile loads and possess no bending or shearing stiffiiess. 

Kim C-U, Kang J-H, Hong C-S and Kim C-G (2005), Optimal design of filament wound structures under internal pressure based on the semi-geodesic path algorithm . Compos Struct, 67,443-452. 

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