committee developed the following broad definition of lightweighting in military systems:¹ Lightweighting is the process of reducing the weight of a product, component, or system for the purpose of enhancing certain attributes, notably (1) performance, (2) operational supportability, and (3) survivability.

In developing this broad definition, the committee wished to emphasize that lightweighting should be viewed as a means of achieving a variety of desirable features:

• Improved fuel economy that would reduce both fuel expenditures and the logistical support needed to supply fuel to forces deployed in remote and hostile locations;
• Better performance in the form of, for example, increased speed, mobility, maneuverability, range, and payload capacity;
• Better operational supportability in the form of, for example, better transportability, durability, repairability, and maintainability; and
• Improved survivability.

Lightweighting is critical to optimizing vehicle performance and capability and to reducing fuel use and costs. Lightweighting can also confer the benefit of flexibility and adaptability. For example, a vehicle that can be made lighter without compromising survivability provides the flexibility to add new capability—e.g., to add armor in a modular fashion or to add payload—without increasing weight beyond the original weight or even while maintaining an overall lighter vehicle. In general, vehicles can be adapted for different uses, such as responding to evolving threats.

Lightweighting encompasses the design, development, and implementation of lightweight materials, components, and other technologies as well as the capability to manufacture and produce such materials and components at reasonable cost.

Under the committee’s broad definition, lightweighting demands a true systems approach. A focus on only one vehicle attribute may result in a weight reduction but may miss the more significant benefits that could be attained through a more systematic consideration of lightweighting throughout a vehicle system’s design cycle. Lightweighting must be done at the systems level to ensure proper balance with all other critical requirements. Use of advanced, lightweight materials, and optimization of all materials and structural configurations at the systems level, are key to achieving optimal systems performance and the lightest weight.

A systems approach to design might consider not only the development and use of lighter (low-density) and high-specific-performance² materials, but also:

• Creative architectural and component designs that provide multifunctionality;
• Manufacturing methods that enable the use of new designs and material combinations as well as the reduction of manufacturing defects (thus improving durability and service life);
• Research to improve understanding of materials’ response and failure mechanisms; and
• Enhancement and broader use of computational models that can accelerate the materials development and qualification cycle through integrated computational materials engineering.

The committee addressed its charge by reviewing illustrative examples of lightweighting in air, sea, and land vehicles, with a focus on military applications. It also considered some of the opportunities available to implement lightweight solutions. Although not definitive, the review found good examples of lightweighting implementation in military vehicles, but there is still much that can be done. Viewing lightweighting broadly, as defined by the committee, and at the systems level may help bring opportunities to light.

¹ Although this definition also applies to civilian vehicles, the main focus of the report is military vehicles, and so the attributes of interest and the wording used are tailored for military applications.

² For example, high specific strength, which is defined as strength divided by density.