of damage and environmental conditions, and avoidance of detection. Lightweighting can also confer a further benefit in the form of flexibility and adaptability.
The means of reducing vehicle weight has also been viewed narrowly, as a process of replacing the materials in a system with lighter2 alternatives. Although this is indeed one approach to reducing weight, lightweighting can be achieved in many other ways: for instance, by changing structural shape or tailoring the spatial configuration of dissimilar materials (as is done with fiber composites and sandwich panels) to make the most efficient use of each material.
Most importantly, lightweighting can be achieved at a systems level, which involves considering the potential for lightweighting from the beginning of the design process. For example, creative architectural designs that involve multifunctionality in components or make use of multifunctional materials can emerge when lightweighting approaches are integrated into the engineering of new systems. A systems-level perspective also incorporates considerations such as the availability of new or advanced manufacturing methods that enable the development and processing of new materials and materials combinations, the production of shaped parts from the materials, and the reduction of manufacturing defects (which improves durability and service life).
System engineering design could support the use of more aggressive design strategies to optimize structure and function, based on (1) optimization of system design and topology using available or new technologies and components, (2) improved understanding of response and failure mechanisms of materials, (3) improved associated physics-based computational models, and (4) improved associated tools for prediction of product performance and life.
The committee notes that strategic, national-level concerns can be addressed in part by lightweighting, or can seriously impede lightweighting. The committee identified three of these concerns as having particular strategic importance: (1) the protracted time required to develop and field military vehicles; (2) unsustainable energy use, which has implications for both military operations and long-term national security and economic prosperity; and (3) the declining domestic capability for manufacturing, which threatens the ability to achieve lightweighting. The committee notes that programs to support the manufacturing capabilities needed to produce lightweighting technologies could also constitute part of a national strategy to rebuild cutting-edge manufacturing capabilities in the United States. Table 6-1 illustrates the relationship between these national-level concerns and the committee’s definition of lightweighting.
Below, the committee offers five recommendations for improving the implementation of lightweighting in military (and civilian) vehicles. They reflect the committee’s broad view of lightweighting and what it can accomplish. The connections between the three national concerns outlined above and these five recommendations are shown in Figure 6-1.
Finding 1: One consequence of lengthy acquisition processes is that changes in threats and operational requirements in areas of conflict can outpace the development of new military vehicles and vehicle technologies. The ability to keep up with evolving requirements could be improved by both reducing the time required for development and improving the capability to design flexibility and adaptability into vehicle systems. Both goals require increased capability in digital design, especially for the integration of materials and design configurations. Such capability could significantly improve the effectiveness of current systems engineering processes.
2 “Light” and “lightweight” as used in this report denote materials having high specific properties (e.g., high specific strength, defined as strength divided by density) or, more generally, high specific performance. Historically lightweighting has been achieved by focusing on lower-density materials with high property values (e.g., composites). However the converse is equally viable—using traditional-density materials with enhanced property values, which then allow reduced total weight via reduced cross sections.