Resistance-based Strain Sensor Sheet: Developing and Implementing a Prototype for Large Area Damage Detection

Abstract

Structural Health Monitoring (SHM) is the process of periodically or continuously monitoring structural parameters, and transforming raw data into useful information, in order to evaluate a structure's behavior. The long-term goal of SHM is to provide infrastructure managers with useful information to make informed decisions regarding a structure's safety and serviceability. Bene ts of more complete SHM methods are numerous. Most importantly, predictions of where, how and when a structure will fail can be made, leading to a more proactive approach to damage detection. Furthermore, damage can be pinpointed, improving repair e ciency, saving time and money. SHM can also be applied to understanding a structure's behavior in general, informing future design decisions. While SHM is a relatively young eld, signi cant research in one- dimensional strain-based monitoring has been performed, and successful monitoring has stemmed from this research. While one-dimensional strain-sensing is an e ective monitoring strategy when strain or damage orientation can be predicted, it proves problematic when damage direction is more di cult to anticipate. Therefore, two- dimensional strain sensing, via large area electronics (LAE) is an important research area, and will be the focus of the following research. Two-dimensional strain sensing is currently at the lab prototype and testing stage. To this point, only basic, small-scale lab tests have been performed to evaluate the feasibility of damage detection using LAE, and no on-site testing of real structures has been performed with this technology. One objective of this study is to address existing problems in current two dimensional sensor sheet technology and implementation, and to develop and prototype an improved two-dimensional resistance-based strain sensor sheet, bringing two-dimensional strain sensing one step closer to real structure implementation. A critical detail in LAE for damage detection is the way the sensor sheet is xed to the structure. While previous research has successfully addressed this issue for sensors bonded to degrading materials such as concrete, this research explores behavior of three new adhesive options for sensors attached to a non-degrading material. The most suitable adhesive is selected by performing both non-damage and damage tests using individual full-bridge strain sensors. Factors such as set time, strain transfer and adhesive strength are considered in selecting the adhesive. Using the selected adhesive, the sensor sheet is rigorously calibrated with the selected adhesive, and the sensor sheet is used to measure strain for small loads.