2. Composite microstructures and associated descriptors

Microstructure refers to the characteristics of the material's internal structure, comprising several immiscible phases of varying internal lengths. For fiber-reinforced composites, the appropriate length scales are those that reveal the partitioning of the material into continuous regions (called phases) such as individual fibers, or quasi-continuous zones such as unidirectional fiber bundles called roving. There are several important geometric elements to consider when modeling composite processes:

• Synthetic composites are reinforced by fibrous structures resulting from a manufacturing process whose aim is to build controlled periodic architectures such as fabrics (multiaxial, etc.) or totally random ones such as mats