Abstract
Structural systems are susceptible to damage caused by deterioration, changing operating conditions, natural disasters, or unexpected events. Undetected damage can propagate and cause catastrophic failure. Thus, structural health monitoring (SHM) is crucial for identifying damage initiation, directing repair, and ensuring system safety/reliability. This presentation outlines a new paradigm shift in SHM, where sensors are designed from a materials perspective stemming from a “bottom-up” design methodology. By manipulating materials at the molecular level and then scaling them up to tangible length scales, one can engineer novel stimuli-responsive materials that respond to structural response (or damage) features of interest. By coupling these materials with tomographic methods, spatial structural sensing could be achieved. This seminar will highlight a few examples. First, nanocomposite thin films are coupled with electrical impedance tomography (EIT) to realize densely distributed 2D sensing. Damage, such as cracks, strain fields, and pH/corrosion, could be identified and localized. EIT can also be extended to map the conductivity of patterned nanocomposites for strain field monitoring. Second, subsurface structural sensing could be achieved by embedding passive thin film sensors in structural components and then interrogating them using an electrical capacitance tomography (ECT) measurement strategy and algorithm. Cross-sectional images of structural components could be used to directly visualize and characterize defects (e.g., voids or cracks) in the component. In addition, noncontact and subsurface pH/corrosion and strain sensing was also validated.
Short Bio
Dr. Ken Loh is a Professor and was the former Vice Chair (2018-2021) of the Department of Structural Engineering at UC San Diego. He is the Director of the Active, Responsive, Multifunctional, and Ordered-materials Research (ARMOR) Lab and is the Associate Director of the UC San Diego, Jacobs School of Engineering, Center for Extreme Events Research (CEER). He is also an affiliate faculty member of the Materials Science & Engineering Program and the Center for Wearable Sensors. Dr. Loh received his B.S. in Civil Engineering from Johns Hopkins University in 2004. His graduate studies were at the University of Michigan, where he completed two M.S. degrees in Structural Engineering (2005) and Materials Science & Engineering (2008), as well as a Ph.D. in Structural Engineering in 2008. He started his Assistant Professor career in January 2009 in the Department of Civil & Environmental Engineering at UC Davis, before joining UC San Diego in January 2016. His research interests are in multifunctional and stimuli-responsive materials, tomographic imaging techniques, wearable sensors, active metamaterials, and soft material actuators applied towards solving problems related to human performance assessment and structural health monitoring.