Wet lay-up processes

Wet Lay-Up Process. Formulations are impregnated by hand or sprayed into fibers that are in the form of woven, knitted, stitched, or bonded fabrics. This is usually accomplished by rollers or brushes. Spray-up is a partly mechanized version of the hand lay-up process. The thermoset precursor is applied by means of a spray gun to the mold surface simultaneously with the chopped glass-fiber roving. Laminates are left to cure under standard atmospheric conditions. 

Wind turbine blades represent one of the success stories for the RP industry with increasing market demand for longer blades. This has caused designers to incorporate carbon fibers adding stiffness, while blade manufacturers are moving away from wet lay-up processes to ensure that the several tonnes of materials that make up a blade can be processed safely and quickly. As a result the raw materials have changed from wet-lay up systems to prepregs and both wet and dry infusion materials (Chapters 4 and 5). 

Filament winding is basically a simple process, although numerous modifications have been developed to improve product quality. Moldings can be produced by either a wet lay-up process or from prepreg. 

To prevent the end-zone debonding of the FRP soffit plate, special anchorage schemes are used. Relatively rigid steel plates placed over FRP plate and epoxy bonded to both the plate and the RC member surface or the use of U-shaped FRP strips formed by a wet lay-up process are the common types of end anchorage (Figure 5.16). 

The wet lay-up process, where the polymer matrix also acts as the adhesive of the upgrading composite (Flollaway, 2008). 

This subsection wUl include an overview of installation methods with particular focus on wet lay-up and the various components that lead to successful CFRP system installations. Wet lay-up is the procedure considered best practice as an installation method. As detailed below, this includes the saturation of the fiber system through a mechanical saturator. Other installation methods, such as dry lay-up, may lead to inadequate fiber saturation and delamination of the CFRP system. Dry lay-up is the application of dry fiber sheet and in situ application of the epoxy to the fiber at the point of application. This is deemed to be an uiueliable installation method. Detailed steps of the wet lay-up process follow. 

The saturated carbon fiber is applied to the inside surface of the host pipe in a wet lay-up process as shown in Figure 2.6. The wet-out fabric is pressed to the inside surface of the host pipe to achieve intimate contact. Any entrapped air between layers is to be released or rolled out without wrinkling of carbon fibers. Fabric kinks, folds, or severe waviness are not acceptable conditions. 

While it is unlikely that a wet lay-up process can achieve fiber volume fractions of 50%, it must be noted that the average thickness specified in this analysis is... 

Before electroless coating the carbon fibers were cleaned by ultrasonic vibration in acetone solution to remove the sizing materials. Then, the cleaned specimens were heated in an oven with working temperature of 100°C in order to dry the fiber surface. The composite preparations were done by wet lay-up process. 

Key words Ni-P coating, wet lay-up process, DMA, Modulus, Glass transition temperature (Tg)... 

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