D Reinforcements

The most common fabric is (+45°, 0°, —45°), in which the 0° lay-up contains 50% of the fiber, with the other 50% spread equally between the 45° layers. Angles of 60° and 30° do necessitate major changes to the machine setup, which becomes time consuming and expensive. The width of a given machine is fixed (e.g. 1270 mm) and produces good quality fabrics above 1000 gm .  

The fabric is penetrated by a stitch bar containing up to 700 needles and the method of stitching used is important  

A smaller stitch length will improve drape, but raises production costs. 

The stitch style affects the handling of the fabric. A chain stitch (linear) gives good drapeability, whilst a tricot stitch (zig-zag) gives a more stable fabric. A modified tricot stitch can provide optimum drape and stability. 

After stitching, the fabric can be slit to specified widths for use in, say, pultrusion. 

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For all butt groove welds (single and double), height is the lesser of the measurements made from the surfaces of the adjacent components for single groove welds, I.D. reinforcement (internal protrusion) is included in a weld... 

The initial intent of this review is to address the mechanisms of stress redistribution upon monotonic and cyclic loading, as well as the mechanics needed to characterize the notch sensitivity.5 13 This assessment is conducted primarily for composites with 2-D reinforcements. The basic phenomena that give rise to inelastic strains are matrix cracks and fiber failures subject to interfaces that debond and slide (Fig. 1.1).14-16 These phenomena identify the essential constituent properties, which have the typical values indicated in Table 1.1. 

R = weight % of resin in the composite r = weight % of reinforcement in the composite D = resin density d = reinforcement density... 

Braids Is used to give high strength three-dimensional (3-D) reinforcement, incorporating more than one type of fiber, if required. Conventional woven fabrics are limited to providing reinforcement at orthogonal orientations, but many reinforced plastics structures are loaded in non-orthogonal fashion. Woven fabrics are, therefore, not necessarily mechanically efficient. 

FIGURE 3. Schematic diagram of the fabrication of glass composites with 3-D reinforcement by infiltration of molten glass into a porous ceramic preform. 

Figure 8. Principal strengthening methods currently used (a) modified flitch upgrading (b) tension zone upgrading (c) compression and tension zones upgrading (d) reinforcement of beams or joints above decorative ceilings [15] (reprinted with permission from Rotafix Ltd.).

Crosbie GM, Nicholson JM, Deering LA, Pseudo 3-D reinforcement with stretch-broken carbon fibers in a borosilicate glass matrix, JP Singh, Bansal NP eds.. Advances in Ceramic-Matrix Composites II, Ceram Trans, American Ceramic Soc Inc, Indianapolis, 46, 211-222, Apr 25-27 1994. 

Table I compiles the mechanical properties of various C/C composites at room temperature. After 4 to 6 densification cycles and final heat treatments at 1000°C, unidirectional (1-D) reinforced...

Figure 12 shows schematically the stress-strain curves of 1-D, 2-U, and 3-D reinforced C/C composites at room temperature. 1-D composites exhibit brittle fracture behaviour, the 2-D composites fail in a "semi-brittle" manner by a continuous step drop in load. °The mode of failure of 3-D composites, however, is not of a brittle type. One observes strain rates up to 5%. This nontypical fracture behaviour of 3-D composites is due to a continuous crac system inside the composite, as illustrated schematically in Fig. 13. This crack pattern depends on the weave pattern and originates during the processing of the carbon/carbon composite, as a result of the heating and cooling cycles. These cracks are able to annihilate fracture energy. If the cracks are closed at higher temperatures because of the thermal expansion of the material, the typical brittle fracture behaviour of C/C composites is found (see Fig. 13). ° ...

Fig. 14. Linear thermal expansion and coefficient of thermal expansion of 1-D reinforced C/C...

Each reactor module is located inside a 17 m I.D. reinforced concrete Reactor Pool. The Reactor Pool is located inside the Reactor Building (RB) which houses also auxiliary systems... 

Prom a historical point of view, the development of SRPMs started with the in situ production of 1-D-reinforced variants. This occurred mostly with solid phase extrusion forming, and techniques exploiting melt shearing in the solidifying melts [7]. 

Parkinson, D. Reinforcement of Rubber. Inst. Rubb, Ind., London, 1957... 

Cameron, J. and Pierce, W. D., Reinforcement, reward, and intrinsic motivation a meta-analysis, Rev. Educ. Res., 64,363,1994. 

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