b'Figure 2. Sequence of digital imageprohibitive and an experimentaldesign of tube architecture for correlation images from a typical hoopimpossibility. The proposedenhanced performance in specified burst test: (a) Initial uniform hoop strain,innovative approach combinesnuclear applications. In addition, (b) a frame just final fracture showing highly localized increase in strain (rednew modeling schemes verifiedthese experiments revealed a unique regions) where fracture is about toby well characterized experimentsfailure mode with microcrack occur in a single yard over its width, andto quantify uncertainty in thenucleation and growth only up to (c) frame after final fracture. (d) Failurepredicted results. By quantifyingthe width of a single yarn (Figure 2). mode of crack initiation in a single yarn is show from a separate test the influence of heterogeneity andThis crack growth behavior is variability in performance, one canreflected as periodic oscillations in successfully predict the reliability ofthe load-displacement response.operation under extreme conditionsComputationally, elastic constants in and hence safety assessment can bevarious orientations were calculated made with confidence. by using a curved repeatable unit Accomplishments: cell (RUC) to account for curved We have experimentally determinedgeometry of the tube. This analysis, the strength and failure behavioronce for all, settles the issue of of four SiCf/SiCm compositeusing homogenization methods for architectures (Figure 1) with biaxialcomposites with curved geometries and triaxial weave orientations atand quantifies the degree of difference 45 and 600, under various stressin elastic properties between curved states (axial compression, internaland planar geometries. To account pressure, and rotating flexure). Itfor the high-volume fraction of yarns was found that the braiding anglein the SiCf/SiCm composites, a new had the most significant influencemethod called chipped-away model on the strength under tensilewas developed. A multi-scale model hoop burst and flexural loading,using Mori-Tanaka method was whereas the effect of fiber angleimplemented to account for high was not significant for compressionporosity and calculate degradation in loading. These results point to theYoungs modulus of the SiC matrix. importance of customizing theThe appropriate boundary conditions 58 2022|AFC ACCOMPLISHMENTS'