Structure Quantification and Gestalt of Continuous Fiber Reinforced Composite Microstructures for ICME
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Structure Quantification and Gestalt of Continuous Fiber Reinforced Composite Microstructures for ICME Stephen Bricker1,2, J.P. Simmons1, Craig Przybyla1*, and Russell Hardie2 1
Air Force Research Lab, Wright Patterson Air Force Base, OH 45433, U.S.A. University of Dayton Research Institute, 1700 S. Patterson Blvd., Dayton, OH 45469, U.S.A. *Corresponding Author: [email protected] 2
ABSTRACT Continuous fiber reinforced composites (RFC) are hierarchal and complex at multiple scales. In this work, tools are developed to automate the 3D characterization and quantification of the overall microstructure. Structure quantification enables accurate representation for material simulation and property prediction for the integrated computation materials engineering (ICME) of RFC based components. Relationships are developed to describe the key attributes of the microstructure at multiple scales including the individual fibers, tows, weave, porosity, and secondary matrix phases, which are treated as 'gestalts' of the structure. Here gestalt refers to the essence of shape or complete form of key features of the microstructure such as those of the tow architecture of the textile. Visualization tools are developed based on an artificial color scheme that allow the visual recognition of whole tows instead of just the collection of simple lines and curves representative of the fibers, which provides means whereby the gestalt of the microstructure can be visualized at the tow scale. These tools are demonstrated using a 3D dataset of the SiNC/SiC S200 ceramic matrix composite material (CMC) obtained via automated serial sectioning. Methods are then demonstrated to generate microstructure models representative of the characterized material for finite element analyses (FEA).
INTRODUCTION Advanced ceramic matrix composites (CMC) are currently being studied as alternatives to metal alloys for hot components in turbine engines because of their strength retention at high temperatures. Legacy superalloys are temperature limited above 900 ˚C which is near their melting temperature, but some CMCs can retain significant strength at temperatures >1200 ˚C. Although CMCs retain strength at high temperature, they exhibit lower fracture toughness than metals. This is generally attributed to the existence of weak points in the microstructure which nucleate cracks. A major focus in the development of CMCs is limiting crack formation and growth by microstructural organization. Analyzing and understanding the microstructure is key in finding weak points in the material, and characterization of fiber as well as tow behavior will give a more full understanding of the microstructure in woven CMCs. CMCs are composed of a ceramic matrix that surrounds the continuous fiber reinforcement. CMCs are laid up in a manner similar to continuous fiber reinforced polymer matrix composites as unidirectional laminates or 2D/3D woven textiles. Typically CMCs are processed through one of three methods: melt infiltration (MI), chemical vapor infiltration (CVI) or
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