T-W. Chou and R. kaniva The feasibility of fabricating a wide range of preform architectures has been demonstrated. Figure 4 illustrates the integrated research plan for multi-step preform reinforced composites, from preform design and fabrication to composites processing and characterization 3 5. ANALYSIS AND MODELING OF COMPOSITE THERMO-ELASTIC BEHAVIOR A methodology has been developed to analyze the composite thermo-elastic behav- ior through the use of preform modeling to represent the fiber microstructure and micro-mechanical analysis to determine the effective properties. A representative volume element(macro-cell) is first identified for a given three-dimensional pre form. Geometric models representing the fiber morphology of macro-cell are then constructed. Further decomposition of the macro-cell into simpler elements termed unit-cells' is then carried out. The macroscopic behavior of the textile composite is obtained from the properties of the unit-cells and a set of load sharing relationships among the unit-cells. using an averaging technique [41 6. CHARACTERIZATION OF TEXTILE CMC PERFORMANCE As an example of the characterization of textile CMC performance, the damage behavior of 2-step and 4-step braided composites are reviewed here. The study of damage mechanisms and evolution in three dimensional SiC-SiC fabric composites, fabricated by the chemical vapor infiltration (CVI) route, have led to the following Phase 1 Phase 2 Phase 3 Figure 5. Damage stages in CMC