SBIR-STTR Award

The goal of the proposed project will be to develop a hybrid structural health monitoring (SHM) system that can detect both microcracks and localized damage/delamination in composite structures.  The hybrid system will combine the unique sensing capabilities of carbon nanotubes along with those of a piezoelectric sensor network to sense the location, nature and extent of damage.  This system combines the key capabilities of the research team in piezoelectric health monitoring (Acellent Technologies) and sensing of damage in composites using networks of carbon nanotubes (University of Delaware). In order to localize the detected damage using the carbon nanotube sensors, a thin dielectric film (SMART Layer) with distributed electrodes will be developed.  The distributed electrodes will be utilized to measure the conductivity at different locations across the structure.  The localized damage in the structure will be measured by the conductivity change from the electrically conductive carbon nanotube networks formed inside the polymer matrix.  Additionally, the SMART Layer will include an embedded network of piezoelectric actuators/sensors to detect/verify the localized cracks and delaminations.  The integrated SHM system will be able to detect initiation of damage and monitor its growth. BENEFIT

Keywords:
Carbon Nanotubes, Composites, Structural Health Monitoring, Piezoelectric Sensing, Damage Detection, Micro Crack Detection, Electrical Resistance, Hybrid Sensor Network

Acellent Technologies and University of Delaware jointly propose to develop an integrated system of carbon nanotubes (CNT) and piezoelectric sensors for structural health monitoring (SHM) of composite structures. The proposed integrated hybrid SHM system will detect the initiation of damage and monitor its growth in composite structures. This system will combine the unique sensing capabilities of CNT and piezoelectric sensors. Both piezoelectric sensors and distributed electrodes for CNT sensors will be built-into one pre-networked, pre-positioned layer called the SMART layer. The distributed electrodes on the SMART Layer will be utilized to measure the conductivity of the CNT network inside the polymer matrix, at various locations across the composite structure. Microcracks in the structure will be determined by the change in electrical conductivity of the CNT sensor network. The piezoelectric sensor network on the SMART Layer will be utilized to detect and quantify the localized cracks and delamination. In phase I, the team successfully demonstrated the feasibility of both the CNT and the piezoelectric SHM system for damage detection on composite coupons. In phase II, the team will refine the software systems and perform hardware integration to develop a hybrid SHM system with user-friendly interface for damage detection in composite structures.

Benefit:
Anticipated

Benefits:
The innovation of the proposed system has many advantages: 1) Increased safety, reliability and robust in-situ health monitoring (early warning system) 2) Complete damage information ¡V both qualitative and quantitative characterization 3) Reduced inspections and reduced vehicle downtime 4) Maximized lifespan of structures residual life estimate by prognosis.

Potential Commercial Applications:
The technology and system that will be developed in Phase II will serve the interest of not only the aerospace industry but other industries as well that use composite materials including the automotive, shipping, railway and wind turbine manufacturing industries. Automobile bodies, offshore structures, wind turbine blades and railway coach components are prone to frequent mechanical wear and tear due to the environmental, transportational and operational effects under which they need to function. This technology will completely revolutionize the way in which structural diagnosis is performed in these industries and provide a state-of-the-art solution for maintenance and support. This technology will prove very useful for the different industries listed above and serve the needs for maintenance and support for all future generation aircrafts and different composite structures. The developmental results from the current project will be channeled in the coming years to customized products required by the government and industrial companies.

Keywords:
Structural Health Monitoring, Carbon Nanotube, Composite Structure, Delamination, Impact, Smart Laye