to qualify the new configuration for fielding. It can only be hoped that a new armor design comes about without too many loops (as shown in the Figure 2-11 diagram), which are costly in terms of effort. More important, repetitive looping delays the fielding of new armors, which in turn adversely impacts the safety of troops. At the same time, speed must be offset by the need to make sure the armor will perform as expected in the field.
As described, the current armor design paradigm clearly makes it difficult to incorporate a new material into existing armor systems or to use it in an entirely new design. Any path forward for future generations of lightweight armor materials must alter this paradigm, although it will not be an easy undertaking. As has been shown in this chapter, the ultimate performance of an armor system depends on the materials used and on the geometric arrangement of those materials, both of which vary according to threat and the application. The challenge is to represent the complications inherent in materials in a way that allows designers to focus on the materials independently of the specific armor system design or threat that the armor is intended to thwart. As will be shown in Chapter 3, meeting this challenge will require an understanding of how to relate the behavior of a material—especially its failure behavior—during ballistic or blast events to its initial structure and composition. Chapter 4 describes approaches for successfully predicting the theoretical and experimental failure behavior of a protection material for the benefit of the materials research community. Finally, it will be important to convey information about armor performance to those developing armor materials.
It is important to acknowledge the security restrictions that surround protection materials. Such limitations are prudent and necessary but require periodic review to ensure they are consistent with the current state of open knowledge and do not unnecessarily restrict the exchange of information with an open research community when such an exchange would be beneficial to national security.
The information content of this study, which deals with armor systems and armor performance, is bound by both security regulations and export control law. The security limitations generally imposed by the Army in this area restrict the discussion of performance of certain armor system designs against specific threats. These limitations extend to the ability to test armor systems with militarily relevant threats. The details of specific threats and design are generally not published in the open literature. Even the availability of information on armor systems that is not proprietary or classified is often restricted by DoD to DoD and contractors to DoD. The underlying technical basis for these restrictions may be available to researchers working on armor under contract to DoD, but it is not generally available to researchers outside of that context.
In addition, there are export control restrictions that generally limit the distribution of information to U.S. citizens and lawful permanent residents. The restrictions that apply to armor materials cover almost all of the relevant protection materials, including ceramics near theoretical density—among them B4C (boron carbide), SiC (silicon carbide), and Al2O3 (aluminum oxide, or alumina), discussed in Chapter 5—composite materials, arrays of woven cloth, metals, and ceramics, and layers of metals.
Information in the public domain as defined in 22 CFR 120.11 is generally not subject to International Traffic in Arms Regulations (ITAR). The definition of “technical data” that is subject to the export control regulations does not include “information concerning general scientific, mathematical or engineering principles commonly taught in colleges and universities or information in the public domain.”29
The combination of security regulations and ITAR makes it extremely difficult for fundamental research in protection materials to connect to the development of restricted armor systems. Ultimately much of work on armor is restricted. For example, a quick search of the Defense Technical Information Center database for “vehicle armor” indicates that only about 30 percent of the technical documents from 2005 through 2010 are approved for public release. Clear, up-to-date boundaries need to be specified between restricted and unrestricted information and related research. Such a review, however, is beyond the scope of this report.
This report is a public document, and its content is limited to general descriptions of threats, performance, and design that may be discussed without restriction. While the restrictions discussed above suffice for the needs of this study, it is important to note that they can significantly complicate the use of available information in basic research.
2922 CFR 120.10(a)(5).