Filament winding materials

ABL bottle The ABL (Allegeny Ballistic Laboratory) is an internal pressure vessel used to determine the quality and properties of the filament winding material in a vessel. 

Figure 21.57 Basic filament winding system. Source Reprinted with permission from Shaw-Stewart D, Filament winding-materials and engineering, Materials and Design 6, No. 3,1985. Copyright 1985, Elsevier.

Applications. Epoxy resias constitute over 90% of the matrix resia material used ia advanced composites. In addition, epoxy resias are used ia all the various fabrication processes that convert resias and reinforcements iato composite articles. Liquid resias ia combiaation, mainly, with amines and anhydride are used for filament winding, resia transfer mol ding, and pultmsion. Parts for aircraft, rocket cases, pipes, rods, tennis rackets, ski poles, golf club shafts, and fishing poles are made by one of these processes with an epoxy resia system. 

In this section a selection procedure will be developed for injection moulding, since this process is used for the widest range of materials. The choice available for other processes such as, for example, compression moulding, filament winding and vacuum forming, is much more restricted. The approach described will be less mechanistic than the systems described in the two previous sections, requiring the prospective user to be aware of the properties of the various materials available. Because the approach is somewhat different, it would be instructive to run it parallel to the above processes and compare the results. 

There are a number of material options available for filament winding. Typical fibers are fiberglass, carbon and aramid. Fiberglass is still the most commonly used... 

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. 

Process models allow composite case manufacturers to determine the affects of process variable settings on final cylinder quality. Because the cost of a composite cylinder can be as great as 500,000, the ability to simulate filament winding can significantly reduce cost and improve quality. Several computer models of the filament-winding process for both thermoset and thermoplastic matrix materials have been developed. These models are based on engineering principles such as conservation of mass and energy. As such, numerous resin systems and fiber materials can be modeled. 

Regardless of matrix or fiber materials, the key process variables for filament winding are temperature, compaction pressure/fiber tension, and laydown rate. Typical measures of final cylinder quality include degree of cure/crystallinity, void volume fraction, fiber volume fraction, and residual stresses and strains. 

In process modeling of filament winding, regardless of matrix material, the process is considered to consist of several simultaneously occurring subprocesses winding, application of heat and/or pressure, consolidation, and void evolution [16], The process model is consequently broken down into several submodels, each with a distinct function, and each coupled to one another ... 

Figure 13.7 Flow chart showing interrelationship of submodels for filament winding with thermosetting matrix materials...

The fiber motion submodel yields the fiber position during processing. In filament winding, the fiber position is affected by flow of the resin matrix material, expansion of the mandrel, and expansion of the composite. In the fiber motion submodel, only changes in fiber position caused by flow of the matrix are considered. Changes caused by thermal expansion of the mandrel and composite are included in the stress-strain submodel. 

Consolidation and development of interlaminar bond strength for thermoplastic matrix composites have been modeled by two mechanisms intimate contact and autohesion. Intimate contact describes the process by which two irregular ply surfaces become smooth (Fig. 13.10). In areas in which the ply surfaces are in contact, autohesion occurs, and the long thermoplastic polymer chains diffuse across the ply boundaries. Filament winding with thermoplastic matrix materials is considered an on-line consolidation process in that local... 

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 ... 

Hummler, J., Steiner, K.V. Experimental Study of Robotic Thermoplastic Filament Winding of Complex Geometries (1990) Center for Composite Materials, University of Delaware, Newark, Delaware... 

Peters, S.T., Humphery, W.D., Foral, R.F. Filament Winding Composite Structure Fabrication (1991) Society for the Advancement of Materials and Process Engineering, Corina, California... 

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