PROCEEDINGS ARTICLE | April 5, 2012
Proc. SPIE. 8347, Nondestructive Characterization for Composite Materials, Aerospace Engineering, Civil Infrastructure, and Homeland Security 2012
KEYWORDS: Capacitors, Sensors, Skin, Inspection, Fourier transforms, Optical inspection, Capacitance, Structural health monitoring, Bridges, Sensing systems
Health monitoring of civil structures is a process that aims at diagnosing and localizing structural damages. It
is typically conducted by visual inspections, therefore relying vastly on the monitoring frequency and individual
judgement of the inspectors. The automation of the monitoring process would be greatly beneficial by increasing
life expectancy of civil structures via timely maintenance, thus improving their sustainability. In this paper, we
present a sensing method for automatically localizing strain over large surfaces. The sensor consists of several
soft capacitors arranged in a matrix form, which can be applied over large areas. Local strains are converted
into changes in capacitance among a soft capacitors matrix, permitting damage localization. The proposed
sensing method has the fundamental advantage of being inexpensive to apply over large-scale surfaces. which
allows local monitoring over large regions, analogous to a biological skin. In addition, its installation is simple,
necessitating only limited surface preparation and deployable utilizing off-the-shelf epoxy. Here, we demonstrate
the performance of the sensor at measuring static and dynamic strain, and discuss preliminary results from
an application on a bridge located in Ames, IA. Results show that the proposed sensor is a promising health
monitoring method for diagnosing and localizing strain on a large-scale surface.
