G. Ravichandran received his B.E. from the Regional Engineering College, University of Madras, Sc.M, and Ph.D. from Brown University.
Advanced materials such as ceramics and ceramic composites are finding increasing applications in aircraft engine parts such as turbine blades and casings which should be protected against foreign object impact damage. To predict the performance of brittle solids considered for such applications, there is a need to understand the critical conditions for failure and the associated micromechanisms under impact loading conditions. Combined mechanical and electromagnetic loading will be used to assess the role of radial confinement in altering failure modes. Experiments are to be performed over a wide range of strain rates (up to [Image] ) to construct constitutive models for brittle solids. Constitutive models will be based on micromechanical modeling that include the evolution of damage.
Advances in processing metal matrix composites (MMCs) and intermetallics can be used to tailor material properties for potential aerospace applications. Our work focuses on consolidating novel materials under very high pressures and relatively low temperatures to avoid extensive grain growth or large interfacial reaction zones. Techniques for consolidation include shock wave compaction and high pressure quasistatic deformation. The role of process variables such as powder size, dispersion of reinforcement, chemical impurity and pre-compaction heat treatment are being explored. The effect of interfacial properties on the mechanical behavior of particulate reinforced metal matrix composites is being investigated. Modeling of consolidation and mechanical behavior of MMCs and intermetallics are used to improve the processing and performance of materials.
Shear strain localization plays a major role in determining machinability and in influencing failure (brittle/ductile) modes of ductile materials. In this project, the critical conditions for localization will be established experimentally under dynamic loading. The experimental set-up for multi-axial dynamic loading is to be developed as a part of this project. Experiments will be performed to ascertain the role of strain hardening, strain rate hardening, and thermal softening on the onset of localization. Model materials considered for investigation include rate sensitive alloys and steels.
Next generation high performance aircraft such as NASP and SST will have to rely on materials that can withstand very high temperatures for their structural and engine parts. Ceramic composites such as SiC/SiC show promise for high temperature applications. This project involves understanding the mechanical behavior of fiber reinforced ceramic composites based on the mechanisms of damage. Efforts will be made to develop an analytical understanding of damage accumulation and failure based on real time measurements and microstructural characterization.
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