Filament winding configurations

Hybrid Processes. There are also hybrid processes that have evolved to meet specific product needs. As an example, automotive leaf springs utilize a filament winding system to prepare impregnated fiber bundles that are then compression molded to final configuration. 

Figure 5.77 Basic configuration of a mandrel for filament winding, and the principle of a collapsing mandrel...

The major types of layup configuration include hand layup, automatic tape laydown, filament winding, resin transfer molding, and pultrusion. The configuration will depend on the type of reinforcement that is used (i.e., tape, tow, fabric, preform, chopped fiber, etc.) and whether or not it is impregnated with resin at the time of laying in the mold. 

As shown in Fig. 7.2 the main steps of the filament winding process chain are the material supply, tension build-up, heating and consolidation. Depending on the individual winding equipment configuration and winding head technology several different setups are possible. 

Computerized programmable equipment is usually more cost effective where a variety of parts are to be produced or where part configuration is complex, such as a wind turbine blade. Sophisticated software for filament winding such as FGX Windows developed by Entec Composite Machines (Salt Lake City, Utah) allows the manufacturer to create patterns to wrap a pressure vessel, as an example, before winding begins. Filling in a simple menu defines the part geometry, and the computer uses this database to calculate a fiber path for the part and establish the... 

HTS materials, becanse of their ceramic nature, are quite brittle. This has introduced problems relative to the winding of superconducting magnets. One solution is to first wind the magnet with the powder-in-tube wire before the ceramic powder has been bonded and then heat treat the desired configuration to form the final prodnet. Another solution is to form the superconductor into such fine filaments that they remain sufficiently flexible even after the powder has been heat treated. 

Each intermediate filament protein has globular head and tail domains joined by a long a-helical domain. The a-helical domain contains many direct repeats of an amino-acid sequence motif called the heptad repeat. Since an a-helix makes just under two turns in seven residues, each position in a seven-residue repeat will slowly wind around the helix. Thus, if two such helices with heptad repeats interact through hydrophobic interactions of side chains, they will slowly wind around each other. This structure is known as an a-helical coiled coil and is stabilized by the presence of hydrophobic residues at positions 1 and 4 of the repeat. The intermediate filament is built from pairs of proteins in the coiled-coil configuration. Two of these pairs bind together, in an antiparallel, staggered, configuration. Further pairs can then add on where the overlap occurs (Fig. 10.4). 

Jensen (2004) and Jensen and Francom (2005) developed and manufactured the IsoTmss. The continuous truss configuration is produced by winding filaments arotmd a mandrel eliminating bonding at the node point. Each node is established when a filament crosses another filament as it is placed in the desired location and direction down the mandrel. It is the inclusion of a node at the point where the filaments overlap and turn to travel in another direction, aided by the helical formation, that allows a variety of cross-sectional configurations to take place. 

Different configurations can be employed on successive passes and the orientation of the filaments be tailored to the stresses set up in the part. For example, with pipe, continuous helical winding can be employed on a segmental mandrel, an extruded mandrel. 

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