“Spatially Distributed Structural Health Monitoring using Electrical Impedance Tomography”

Bryan R. Loyola, Steven Paradise, Christopher Hall

Sandia National Laboratories

When: Monday, April 7, 2014 at 3:05 p.m.
Where: Warnock 1230


The United States is facing a two-pronged infrastructure problem. Many new structures are being built with state-of-the-art materials that do not perform like traditional engineered materials, while the remainder of America’s civil infrastructure is deteriorating at an alarming rate. A recent American Society of Civil Engineers’ report has rated the civil infrastructure of the United States at an overall D+ rating. In addition, fiber-reinforced composite materials are being introduced into many structures, particularly in aircraft, at a higher rate. Unlike traditional monolithic metals, composites manifest their damage internal to their structure, making the damage barely detectable to visual inspection. Researchers across the world have focused their attention towards creating new sensors, sensing methodologies, and sensor platforms to be able to instrument these structures to detect the onset of damage due to environmental conditions and events. In this talk, a sensing skin approach will be discussed aimed at detecting damage in fiber-reinforced polymer (FRP) materials, like those used in aircraft or wind turbines. A carbon nanotube-based latex paint has been developed and demonstrated to be sensitive to applied mechanical strain, changes in temperature, and cracking via changes in the film’s electrical conductivity. These sensitivities are utilized by an approach called electrical impedance tomography (EIT), which measures the spatially distributed conductivity across the CNT-based paint. Changes in localized electrical conductivity are indicative of strain, changes in temperature, or impact damage in the specified location. This approach allows for the detection, localization, size evaluation, and severity of damage within the sensing region. This talk will explain how EIT has been applied to detecting damage with applied and embedded CNT films in glass fiber-reinforced polymer composites, as well as using the inherent electrical conductivity of carbon fiber-reinforced polymer composites.

Speaker Biographies

Dr. Bryan Loyola is a Senior Member of Technical Staff at Sandia National Laboratories in Livermore, California. He earned a B.S. in Physics from the University of California, Davis in 2005, and his M.S. and Ph.D. in Mechanical and Aeronautical Engineering from the University of California, Davis in 2010 and 2012, respectively. Dr. Loyola specializes in creating sensing methodologies for structural health monitoring applications, specifically using carbon nanotube thin films and electrical impedance tomography (EIT).

Steven Paradise is a Senior Member of Technical Staff at Sandia National Laboratories in Livermore, California. Steven graduated Magna Cum Laude from the University of Utah in 2005 with a BS in Electrical Engineering, and earned his MS in Electrical Engineering the following year, studying nonlinear optical effects under Dr. Steve Blair. In 2006, he began working at Sandia and entered the selective Weapon Intern Program. Since then, he has developed and tested optical technology for use in national security applications, such as improving safety, security, and reliability of weapon systems.

Christopher J. Hall is a Member of Technical Staff in Electrical Engineering at Sandia National Laboratories in Livermore, California. Chris graduated Magna Cum Laude from Utah State University in 2010 with a BS in Electrical Engineering and minors in Computer Science, Mathematics, and Mandarin Chinese. He began working at Sandia that same year and was a recipient of the Critical Skills Master Program Fellowship. He received his MS in Electrical Engineering at the University of Wisconsin-Madison in 2011. His work at Sandia includes the design and operation of a fully automated tester and design of electronic devices for use in national security applications.