Structural shapes manufacture

RPs offers certain important structural and other performance requirements. These requirements provide the designer great flexibility and provide freedom practically not possible with most other materials. However, it requires a greater understanding of the interrelations to take full advantage of RPs. It is important to understand that RPs has an extremely wide range of properties, structural responses, product performance characteristics, product shapes, manufacturing processes, and influence on product performances. 

Pultrusion—Process for the manufacture of composite profiles by pulling layers of fibrous materials, impregnated with a synthetic resin, through a heated die, thus forming the ultimate shape of the profile. Used for the manufacture of rods, tubes and structural shapes of constant cross-section. 

A continuous manufacturing process for composite rods, tubes, and structural shapes having a constant cross-section. 

The described 3DNCOW approach is also suitable for producing some relatively complex net-shaped preforms, such as I, T, II, H, Y, as well as integral truss core and pile structures. Examples of such structural shapes designed and manufactured by 3TEX, Inc., can be found in Mohamed et al. (2001, 2003, 2005), Mohamed and Wetzel (2006), and Bogdanovich et al. (2008). Specific directions of those efforts have been determined by the practical industrial and military market needs and resulted in a broad spectrum of manufactured composite products. 

Pultruded advanced composites used in civil engineering applications are manufactured in three basic structural shapes (Bakis et al., 2000 Hollaway, 2010) ... 

The active element, or material, within the active element gives the fired film its electrical properties. If the active material is a metal, the fired film will be a conductor if it is a conductive metal oxide, a resistor and, if it is an insulator, a dielectric. The active metal is in powder form ranging from 1 to 10 m, with a mean diameter of about 5 m. Particle morphology can be varied greatly depending on the method used to produce the metallic particles. Spherical, flaked, or acicular shapes (both amorphous and crystalline) are available from powder manufacturing processes. Structural shape and particle morphology is critical to the development of the desired electrical performance and, therefore, the control on the particle shape, size, and distribution must be maintained to ensure uniformity of the properties of the fired film [23,24]. 

Profiles are manufactured by extrusion, a technique for which aluminum and aluminum alloys are very suitable. A heated billet, a blank, is forced through a tool, a die, prepared to the same cross-section as is required for the profile. The principle is shown in Figure 37.3. Extrusion is the principal method for making structural shapes, tubes and a great number of small and big sections. 

Uses for FGD byproduct include construction of structural landfills liners for liquid waste ponds road bases parking lots and the manufacture of structural shapes, synthetic aggregates, and artificial reefs. Minnick (1983), EPRI (1987), Smith and Rau (1981), Henzel and Ellison (1990), and Smith (1992C) provide information on FGD byproduct uses. The usual U.S. practice of landfill disposal of FGD byproduct is in contrast to the practice in foreign countries. In Japan, due to the lack of naturd gypsum, the gypsum produced by FGD systems is used in wallboard manufacture. In Europe, waste disposal restrictions also favor the production of usable byproducts. 

Manufacturing techniques are being used to produce a wide variety of structural shapes that are not necessarily limited to surfaces of revolution (e.g., I-beams). This technology is advancing very rapidly because it is very cost effective. 

Mechanical Properties and Structural Performance. As a result of the manufacturing process, some cellular plastics have an elongated cell shape and thus exhibit anisotropy in mechanical, thermal, and expansion properties (35,36). Efforts are underway to develop manufacturing techniques that reduce such anisotropy and its effects. In general, higher strengths occur for the paraHel-to-rise direction than in the perpendicular-to-rise orientation. Properties of these materials show variabiUty due to specimen form and position in the bulk material and to uncertainty in the axes with respect to direction of foam rise. Expanded and molded bead products exhibit Httie anisotropy. 

The type of manufacturing process, reaction conditions, and catalyst are the controlling factors for the molecular structure of the polymers [4-8]. The molecular features govern the melt processability and microstructure of the solids. The formation of the microstructure is also affected by the melt-processing conditions set for shaping the polymeric resin [9]. The ultimate properties are, thus, directly related to the microstructural features of the polymeric solid. 

Steel. Steel shall conform to one of the applicable ASTM specifications referred to by applicable AISC specifications. Other steels not covered by these specifications may be used provided that the chemical and physical properties conform to the limits guaranteed by the steel manufacturer. Structural steel shapes having specified minimum yield less than 33,000 psi shall not be used. Certified mill test report or certified reports of tests made in accordance with ASTM A6 and the governing specification shall constitute evidence of conformity with one of the specifications listed. 

Plates, Shapes, and Bar Stock. Structural material used in the manufacture of main load carrying components of the equipment shall conform to applicable ASTM or API specifications covering steel shapes, plates, bars, or pipe, or a proprietary specification conforming to the minimum requirements of applicable ASTM or appropriate standard. Structural steel shapes having a specified minimum yield strength less than 33,000 psi, or steel pipe having a specified minimum yield strength less than 35,000 psi shall not be used. 

In practice there is often not an extensive range of suitable anode sizes from which to select. Economics may dictate an off-the-shelf choice from a manufacturer or the anode shape may have to conform with the geometric limitations of the structure. Consequently, the choice of anode size and shape is often limited. 

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