Woven roving

Fig. 8. Flexural properties at elevated temperatures. Laminates constmcted from alternating pHes of 46.7-g (1.5-02) mat and 746-g/m (24-o2/yd ) woven roving at a nominal glass content of 45%. A represents bisphenol fumarate (T = 130° C) B, novolak epoxy methacrylate (T = 130° C) C, epoxy dimethacrylate (T = 100° C) D, isophthaUc resin (T = 100° C) and E, oAy f -phthahc resin (T = 80° C).

AH forms and compositions of reinforcements, ie, mats, woven roving, glass, carbon, and aramid, are commonly used with these processes. Special continuous glass strand mats with a thermoplastic binder aHow preforms to be made using thermoforming techniques. These processes are used for tmck and autobody components, medical equipment cabinets, transportation seating, and other parts needed in the intermediate volume range (1,000—10,000 parts/yr). 

Fibrous Composites. These composites consist of fibers in a matrix. The fibers may be short or discontinuous and randomly arranged continuous filaments arranged parallel to each other in the form of woven rovings (coUections of bundles of continuous filaments) or braided (8). In the case of chopped strand mat the random arrangement is planar. In whisker (needle-shaped crystals or filaments of carbon and ceramics) reinforced materials the arrangement is usually three-dimensional and the resulting composites are macroscopically homogeneous. 

A very wide sheet of grp which is known to contain intrinsic defects 1 mm long, is subjected to a fluctuating stress which varies from 0 to 80 MN/m. How many cycles would the sheet be expected to withstand if it is made from (a) chopped strand mat (CSM) and (b) woven roving (WR) reinforcement. The crack growth parameters C and n, and the critical stress intensity factors, Kc, for these materials are... 

Several layers of dry, continuous-strand mat, woven roving, or cloth called preform are placed in the bottom half of a two-part mold, either by a hand-layup or by an automated technique (see Figure 7.90). The mold is closed, and a catalyzed liquid... 

Figure 51, Different types of glass fibers. (1) Continuous strand mat, (2) Surfacing mat, (3) Chopped-strand mat, (4) Woven roving). (Courtesy of Ownes Coming Fiberglass Corp.)...

In resin-transfer moulding (RTM) there is typically a two-part mould, which forms a cavity corresponding to the final product shape. In the process, as shown in Figure 6.11, reinforcement, typically being a woven roving, cloth or mat, is placed (dry) in the female cavity, and then the male half is placed into position. 

Fume handling ducts Spray-up/hand lay-up Gun roving Chopped strand mat Woven roving Polyester Vinyl ester... 

Bulk Molding Compound Sheet Molding Compound Chopped Strand Mat Woven Roving Unidirectional Axial Unidirectional Transverse... 

If required alternate layers of sprayed fibers with layers of woven roving or other fabric construction can be included during the spraying cycle. 

Present day developments include Lotus for production of car bodies, the female mold half is first coated with a gelcoat and dry reinforcement (mainly continuous filament mat and some woven roving) and PUR foam formers are placed on it. The foam inserts have previously been wrapped in continuous filament mat to create a stiff torsion box on each side. The inner male mold, with an airtight peripheral seal, is then placed over the loaded mold and bolted in place and resin is then drawn evenly into the mold by vacuum. 

The systems can include many options surfiice veil, chopped liners, sprayed resin systems, hoop winding strands, helical winding strands, resin bath, unidirectional tape, woven roving tape, pigmented resin surfaces, wax-resin surfaces, gel coats, BPO catalyst, epoxy resins, vinyl ester resins, filled resin systems, abrasive resin systems, polyester foam, syntactic foam, and charting film. 

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