at various length scales to relate microstructural behavior to system performance. This modeling will include the placement of the reinforcing phase, the structure of the matrix phase, and even the degree of bonding at the interface. The methodology could be used to predict (and even control) the final structure of the composite. In other words, future engineers will not merely analyze the mechanics of the final product, but will apply a systems perspective and employ advanced modeling techniques to create reinforced structures that best meet given system requirements. This approach is the key to reduced cost and accelerated insertion of new materials into DoD systems.^29-32

A systems approach is also crucial to understanding the stochastic aspects of composite failure, which is essential for improving the design criteria of these systems. Lack of knowledge in this regard can lead to excessive design safety margins that result in increased weight and cost and lower system performance. A better understanding of the effect of constituent variability on composite properties is crucial to taking advantage of fibers on the market today as well as future fibers, as is the development of micromechanical and continuum-based models that include the stochastic process for the prediction of composite behavior.

The transition to a systems approach is likely to occur gradually, with full implementation 10 or more years in the future. While this approach is evolving, researchers and material suppliers will continue to make incremental improvements in reinforcing fibers, matrix resins, and composite forms and processes.