Composite structures cost

Labor cost in a structure is directly related to part count. If part count can be reduced, then labor costs (and inventory costs) wili decrease. Composite structures are generally composed of many fewer parts than are metal structures. Integral part design and fabrication techniques reduce fastener count and bonding operations. Thus, composite structures can have cost elements that are considerably lower than those for metal structures. 

Often, the manufacturing processes involved for composite structures fabrication are greatly simplified as compared to those for metal structures. Reduced part count results in a much lower assembly cost and overall reduction in the factory labor hours. 

We all hear that composite materials are very expensive, but you have seen in Chapter 1 that, one, material cost is coming down, and, two, composite structures can be less expensive to manufacture than metal structures. An effective structure can be created with an even more-expensive raw material than metals by using less-expensive manufacturing processes. The bottom line is that the initial cost of the structure can in some cases be lower for a composite material than for a metal. Generally, the life-cycle cost of a composite structure is lower than that of a metal structure. 

Two keys to the future use of composite materials are (1) achieving lower raw material cost and (2) developing innovative fabrication techniques that are uniquely suited to the characteristics of composite materials. This duality of approaches is leading to considerable success with composite structures right now, but they also hold the key to the even wider use of composite materials in the future. Let s address the two keys individually. 

Suppose we change our attention from structures in which the driver is functional consideration alone to something like an automobile where cost is also extremely important. We can get the functional job done with other materials, like steel and aluminum and fiberglass in certain places and unreinforced plastic in others. Then, the question becomes can we make a material substitution that will enable us to compete with the cost of these other materials to do a job that with all the other materials we cannot accomplish That is a different kind of question, and then cost becomes an extremely important driver. And, as cost of advanced composite structures goes down, we can expect to see more and more utilization of advanced composite materials. 

Several wick structures are in common use. First is a fine-pore (0.14—0.25 mm (100-60 mesh) wire spacing) woven screen which is rolled into an annular structure consisting of one or more wraps inserted into the heat pipe bore. The mesh wick is a satisfactory compromise, in many cases, between cost and performance. Where high heat transfer in a given diameter is of paramount importance, a fine-pore screen is placed over longitudinal slots in the vessel wall. Such a composite structure provides low viscous drag for liquid flow in the channels and a small pore size in the screen for maximum pumping pressure. 

The use of Kevlar has been confined to specialised applications 98), where high mechanical performance and lightweight properties are essential, because of its present relatively high cost compared with conventional textile materials. These applications can be conveniently divided into two main categories, one where the fibres alone form the final product such as in cables and fabrics and the other where they act as reinforcing elements for the production of composite structures. 

US 5- 10/g. Single-layer hollow fiber membranes contain 10-20 g of polymer per square meter of membrane, for a material cost alone of US 50-200/m2. Thus, using a composite structure consisting of a relatively inexpensive core polymer material coated with a thin layer of the expensive selective polymer reduces the overall membrane material cost significantly. 

The use of carbon materials in electrochemical systems started in 19 century, when carbon electrodes replaced copper ones in Volta batteries and Pt electrodes in Grove Cells. Nowadays, carbon materials are used in many electrochemical applications because of their high electrical and thermal conductivity, low density, high corrosion resistance, low elasticity adequate strength and high purity. In addition, carbon materials are available in a variety of physical structures (powders, fibres, cloths), have a low cost and can be fabricated into composite structures. 

Figure 5.8 Cost-effective design process for composite structures.

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