Mechanical and aerospace structures can develop debilitating defects such as cracks during their service lifetime. Structural Health Monitoring (SHM) and Non-Destructive Evaluation (NDE) represent a collection of strategies and techniques for the timely detection of these and other defects. Guided wave imaging of defects is emerging as a very promising approach for certain critical structures. A framework based on Compressive Sensing and Sparse Reconstruction is being developed for flexible sensing and robust defect imaging using ultrasonic guided waves. This research is being conducted in collaboration with the Center of Advanced Communications. A NASA STTR grant supports a related project that uses fiber optic strain sensors to monitor the health of woven composites.
The goal of this project is to develop high temperature refractory materials suitable for use in launch and propulsion test facilities to withstand thermomechanical loading from rocket exhaust plumes. A suitable aggregate-binder material system is being developed with micro and nano scale features that will result in a refractory material with superior thermo-mechanical behavior at elevated temperatures as well as a low porosity. This work is being conducted in collaboration with Advanced Ceramics Manufacturing and is funded through a NASA STTR grant.
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 was funded through an SBIR Phase I grant from NSF.
Enhanced energy dissipation in blast protection systems is considered in this work. Our approach is to consider materials and structures historically used in lightweight blast-protection systems, such as in armored vehicles, and improve the energy dissipation ability by using viscous dissipation. Analytical and numerical models are used to estimate the energy dissipated by viscous mechanisms in metal sandwich plates. Numerical models use a Coupled Lagrangian-Eulerian finite element simulation. Physical testing using drop-weight impact testing is performed to corroborate results from the analytical and numerical models. An instrumented drop-weight apparatus was custom built for this testing. Liquid loaded structures have been shown to improve the damage resistance of structures both from low velocity impacts and from high velocity blasts. This work was funded by ONR through a Phase I SBIR grant to Ablaze Corp.