The system proposed by PAC and Virginia Tech, along with two additional research partners, the University of South Carolina and the University of Miami, will include an innovative research method for "harvesting" or securing its own power from motions and vibrations in the bridge using piezoelectric materials, thus making it "energy independent," said Dan Inman, the director of CIMSS and the George Goodson Professor of Mechanical Engineering at Virginia Tech.
Piezoelectric materials are able to generate an electric potential when a mechanical stress in the form of vibration caused by traffic is applied.
According to Inman
, the proposed instrument package will use acoustic emission (AE) sensing.
This aspect greatly reduces both installation and maintenance costs for the monitoring system, Inman
This NIST award is among the first under the agency's new Technology Innovation Program, created to support innovative, high risk, high reward research in areas of critical national need.
NIST considers the high-risk elements of the proposal to include the development of the energy harvesting system, the sensors themselves, and the data interpretation, damage assessment and health prognosis software.
said that as "the inventory of bridges continues to age, routine inspection practices will not be sufficient for bridge owners to make informed decisions for safety and maintenance prioritization."
Continuous monitoring of the integrity of the bridge's structure is now needed.
"The only feasible method is to allow engineers to observe various areas of concern such as a retrofit or a previous repair from a remote location.
The monitoring can also be used as a preventative measure against terrorism or vandalism," Inman
Inman, who along with his students created a process allowing the use of smart materials to suppress and harvest vibrations, as well as the inventor of the self-sensing actuation principle for piezoceramic-based devices, explained this work will result in the use of a remote/online, self-powered global monitoring package, allowing for an early warning system.
They plan to call it the Bridge Prognostic System (BPS), and it will be integrated into existing bridge management software to provide sound data for decision-making.
Multiple types of sensors will provide the information.
"The primary advantage of the active sensing approach is that large areas can be scanned efficiently and cracks can be imaged remotely even though they are not actively growing," Inman
"It is clear from recent bridge collapses and the often reactive nature of bridge maintenance, that the major societal challenge of providing a safe and low-cost infrastructure system is not currently being met," Inman