This paper discusses the development status of a self-powered wireless sensor node for steel and concrete bridges
monitoring and prognosis. By the end of the third year in this four-year cross-disciplinary project, the 4-channel acoustic
emission wireless node, developed by Mistras Group Inc, has already been deployed in concrete structures by the
University of Miami. Also, extensive testing is underway with the node powered by structural vibration and wind energy
harvesting modules developed by Virginia Tech. The development of diagnosis tools and models for bridge prognosis,
which will be discussed in the paper, continues and the diagnosis tools are expected to be programmed in the node's
AVR during the 4th year of the project. The impact of this development extends beyond the area of bridge health
monitoring into several fields, such as offshore oil platforms, composite components on military ships and race boats,
combat deployable bridges and wind turbine blades. Some of these applications will also be discussed. This project was
awarded to a joint venture formed by Mistras Group Inc, Virginia Tech, University of South Carolina and University of
Miami by the National Institute of Standards and Technology through its Technology Innovation Program Grant
#70NANB9H007.
A nonlinear piezoelectric wind energy harvester is proposed which has a low startup wind speed and is not restricted to a
specific wind speed. By using the piezoelectric transduction mechanism, the gearbox is eliminated from the system and
the start up speed is improved. Permanent magnets are placed in the blade part of the windmill. The interactions
between the rotating magnets, positioned on the blades, and the tip magnets mounted on the piezoelectric beams directly
and parametrically excite the beams. The nonlinear magnetic force makes the vibrations of the beams nonlinear and can
make the beams bi-stable. This phenomenon is utilized to enhance the power output and to improve the robustness of the
power production. Two designs are presented which incorporate parametric and ordinary excitations to generate electric
power. The performance of each design is examined through experimental investigations. An analytic model is
developed which is verified by the experimental results and explains the nonlinear phenomena captured by the
experimental investigations.
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