RP Directional Property

When compared to unreinforced plastics, the analysis and design of RPs is simpler in some respects and perhaps more complicated in others. Simplifications are possible since the stress-strain behavior of RPs is frequently 

The fabricator has a variety of alternatives to choose from regarding the kind, form, amount of reinforcement to use, and the process vs. requirements (Table 8-28). With the many different types and forms (organics, inorganics, fibers, flakes, and more) available, practically any performance requirement can be met and molded into any shape. Possible shapes range from very small to extremely large, and from simple to extremely complex. 

Orientation of reinforcement The behavior of RPs is dominated by the arrangement and the interaction of the stiff, strong fibers with the less stiff, weaker plastic matrix. The features of the structure and the construction determine the behavior of RPs that is important to the designer. A major advantage is the fact that directional properties can be maximized in the plane of the sheet. As shown in Fig. 8-55 they can be isotropic, orthotropic, etc. Basic design theories of combining actions of plastics and reinforcements 

A microscopic view of an RP reveals groups of fibers surrounded by the matrix. For example, glass fibers at about 0.01 mm (4 x 10 4 in.) in diameter may comprise from 10 to 90wt% of the area of a given cross- 

Terminology regarding directional properties used with RPs include the following  

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Fig. 8-55 Overview of RPs directional properties (a) polar directional, (b) different fiber orientations and tensile fracture characteristics, and (c) stress vs. strain diagrams of RPs.

Orientation terms of RP directional properties include the following ... 

The wide choice available in plastics makes it necessary to select not only between TPs, TSs, reinforced plastics (RPs), and elastomers, but also between individual materials within each family of plastic types (Chapters 6 and 7). This selection requires having data suitable for making comparisons which, apart from the availability of data, depends on defining and recognizing the relevant plastics behavior characteristics. There can be, for instance, isotropic (homogeneous) plastics and plastics that can have different directional properties that run from the isotropic to anisotropic. Here, as an example, certain... 

The reinforcement type and form chosen (woven, braided, chopped, etc.) will depend on the performance requirements and the method of processing the RP (Fig. 6-15). Fibers can be oriented in many different patterns to provide the directional properties desired. Depending on their packing arrangement, different reinforcement-to-plastic ratios are obtained (Appendix A. PLASTICS TOOLBOX). 

An important type of orienting fabricated products concerns applying directional properties to plastics by using fiber reinforcements. Orientation is the alignment of fiber reinforcement within the product that affects mechanical properties. The reinforced plastic (RP) properties increase in the direction of alignment (Figure 3.4). 

Different types of reinforcement construction are used to meet different RP properties and/or simplify reinforcement layup fabricating processes to meet design performance shape requirements. They include woven, nonwoven, rovings, preforms, and others. These different constructions are used to provide different processing and directional properties. 

Figure 5.59 Schematic of an RP composite S-2 glass fiber/burn resistant phenolic adhesive prepreg and aluminum metal lay-up (adhesive by Cytee, formerly American Cyanamid, Havre de Grace, MD) includes use on the Airbus A380 fuselage providing directional properties...

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