If the U.S. is to maintain its technological lead in the area of advanced composites, it is essential that we continue to build a quantitative knowledge base of fundamental materials and process understanding. Only through such a procedure would it be possible to completely exploit the aspects of composites as identified in the structural hierarchy by McCullough.
Present advances in the use of novel cure mechanisms, including the use of microwaves, electronic beams, nuclear energy forms, and other sources are fast being developed on a research level. Surface modification of fibers through plasma treatment, chemical reaction, and deposition and grafting provide new opportunities for the development of interphasial zones. However, again, most of these developments are at the research level and need a committed effort to take them into commercialization and use in the industry. The true challenge lies in developing a composites product design science that will tie microstructural and processing models to performance criteria and design specification through computer tools.
National Laboratories Contributing to Composites R&D
In summarizing, it is worthwhile to keep in mind the results of a survey conducted by the National Institute of Standards and Technology (NIST) in 1990. Table 6.14 ranks processing methods in order of priority with their raw scores.
Table 6.15 ranks the main processing barriers as noted at that point in time. Although the information is slightly outdated, it is the author's view that the ranking is still correct and represents critical needs in the understanding of manufacturing science for composites.
Based on this and other studies, it is possible to indicate that future trends in potential materials will include composites with liquid crystal polymers and molecular composites (especially as integrated with RTM), smart materials, and functionally gradient materials, all of which are under intense study in Japan.
It may be useful in summarizing to comment briefly on a recent assessment by MITI on Japanese industrial technology. MITI concluded that:
This would seem to imply that even the Japanese feel that while they can successfully compete in the area of production, they are lagging in fundamental research. Their developmental methods would thus seem to assure them of a high degree of success using a highly changed form of manufacturing science (i.e., one which is more applied than basic and more integrally linked with the product development system). The focus of their manufacturing science system (such as it is) may be simplified to the schematic shown in Figure 6.18.
The Japanese focus on using existing materials, processes, and technologies to develop new and improved products, with new materials, processes, and technologies being by-products of the creation of new markets. This is in stark contrast to the paradigm often used in the rest of the world, where a product or process is often developed first and then a market identified. However, as will be explained in the next chapter, the Japanese will often see an opportunity for a new market (as in the civil engineering area) and then go about developing it simultaneously with the development of new material forms (for example, grids by Shimizu, and Tow Sheet by Tonen).
Processing Methods Ranked in Priority as per NIST Survey
Ranking of Potential Barriers to Processes
Figure 6.18. The Focus