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    Nanostructured Ceramics

    This work was funded by the Office of Naval Research (ONR) and was performed in collaboration with Advanced Ceramics Manufacturing, Tucson, AZ. The research goal of this effort was to develop strategies to reduce the size of the grains (crystals) in silicon nitride materials in order to improve properties such as toughness and hardness. (Silicon nitrides are being developed for use in high-temperature structural applications but their lack of toughness has proved to be an impediment.) Strategies such as the addition of nano-sized secondary phases such as carbon nanotubes were developed and shown to be effective in refining the microstructure and improving the toughness of these ceramics. Two graduate students obtained a Masters degree based on this work. Two ME undergraduates spent a summer each assisting in this research project.

    Delamination in Laminated Composite Materials

    This project, funded by ONR and Materials Sciences Corporation, PA, explored analytical methods for predicting fractures at interfaces in laminated composite materials. A method was developed, using principles of solid mechanics, to calculate parameters that can predict when fracture can occur at the interfaces of layered materials. Three graduate student Masters theses contributed to this work.

    Mechanics of Shape Memory Alloy Composites

    This project, funded by ONR, explored the mechanical behavior of a special class of metal alloys called shape memory alloys. Shape memory alloys have some unique properties wherein their shape can be changed quite significantly and then restored by a simple heating action. The concept explored in this research was to create structural composite material parts with embedded shape memory alloy wires which would allow the parts to be reconfigurable. A nonlinear, micromechanics-based analytical model was developed to predict the behavior of shape memory alloy composites. Two graduate students wrote their Masters theses based on some of this work.

    Constitutive Model for Carbon Carbon Composite Materials

    A constitutive model has been constructed for a Carbon/Carbon composite material that is used in the leading edges of the space shuttle. This model has been integrated as a user material subroutine in the finite element code ABAQUS.

    Fabrication and Characterization of Biomimetic Ceramics

    Great complexity in structure is seen in nature’s biological composites. These natural biocomposites achieve a damage tolerance 10,000 times higher than their individual constituents via a multi-length scale (third order), crossed lamellar architecture. In this research project, we plan to work with Advanced Ceramics Manufacturing (AZ) to improve the damage tolerance of ceramic systems by mimicking the crossed lamellar microstructure found in sea shells such as Strombus Gigas. It is believed that processes similar to those used in Fibrous Monolith fabrication could be adapted to engineer third order biomimetic micro-structures. Ultra tough ceramics would enable impact resistant turbine blades, multi-hit capable armor, high performance – high reliability rocket motors, chip resistant cutting tools, and more reliable hard tissue medical implants. This project aims to develop an advanced, biomimetic, damage-tolerant, ceramic composite material for high performance structural and thermal protection applications. These ceramics will have high toughness, the ability to resist corrosive environments, and the possibility of use in thermal protection systems. This work is funded through an SBIR Phase I grant from NSF.

    Lightweight Structures in Roadside Blast Protection

    Enhanced energy dissipation in a blast protection system is considered in this work. Our approach is to consider materials and structures historically used in lightweight blast-protection systems like an array honeycomb cells and improve the energy dissipation ability. This work is funded by ONR through a Phase I SBIR grant to Ablaze Corp.