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Nanocomposites for Distributed Structural Monitoring and Damage Detection

Speaker: Dr. Kenneth J. Loh,
Assistant Professor, University of California, Davis, Department of Civil & Environmental Engineering, One Shields Avenue, 2001 Engineering III, Davis, CA 95616, USA Abstract: Structural deterioration, excessive loading, impact damage, and corrosion have been identified as critical and long-term problems that constantly threaten the integrity and reliability of structural systems (e.g., civil infrastructures, aircrafts, and naval vessels). In particular, the field of structural health monitoring (SHM) and damage detection provides quantitative global- and component-scale structural response data for monitoring the performance of these structures; however, most sensors are subjected to performance limitations (e.g., sensitivity, dynamic range, bandwidth, and form factor) and only offer measurement of structural behavior at discrete locations. In this regard, nanotechnology offers a plethora of nanomaterial fabrication techniques for the design of next-generation multifunctional nanostructured systems to solve complex engineering problems. Multifunctional systems are defined to possess a diverse suite of engineering functionalities including self-sensing, actuation, self-healing, power harvesting, among many others. Here, carbon nanotubes are employed and encoded with a variety of electrochemical and electromechanical sensing transduction mechanisms for structural health monitoring and damage identification. First, using a layer-by-layer nanocomposite assembly technique, the films' electrical properties change linearly in response to applied external stimuli (e.g., tensile-compressive cyclic loading and pH). When coupled with radio frequency identification (RFID) technologies, a low cost and high performance passive wireless sensor is fabricated for densely-distributed SHM. Laboratory validation studies demonstrate that these sensors can measure strain and pH/corrosion at its instrumented locations, but damage localization requires interpolation between sensors. Alternatively, the proposed carbon nanotube-based films are paired with an electrical impedance tomographic conductivity image reconstruction algorithm. Specifically, the nanocomposite "sensing skins" are validated for spatial strain, pH, corrosion, and impact damage sensing and is shown to be capable of accurately identifying damage (i.e., strain, impact, and corrosion) location and magnitude. Biography Dr. Kenneth J. Loh is an Assistant Professor in the Department of Civil & Environmental Engineering at the University of California, Davis. He received his B.S. degree in Civil Engineering from Johns Hopkins University in 2004. He continued his graduate studies at the University of Michigan where he completed his M.S. degree in Civil Engineering in 2005, a second M.S. degree in Materials Science & Engineering in 2008, and a Ph.D. degree in Civil Engineering in 2008. His research interests include the development of multifunctional nanocomposites, biologically-inspired materials for sensing, actuation, and power harvesting applications, and wireless sensing.

Location: Kaprielian Hall (KAP) - rielian Hall 209- On Webex. Please call department for more infomation

Audiences: Everyone Is Invited

Contact: Evangeline Reyes