Session: 04-15-01: Congress-Wide Symposium on NDE & SHM – NDE and Prognostics in Structural Applications

Paper Number: 71331

Start Time: Tuesday, 10:25 AM

71331 - Ac Based Sensory System for Carbon Based Trc for Shm 

Textile reinforced cement is a preferable concrete building technology for thin walled structures. The technology combines high strength cement-based matrix with a biaxial textile mesh, made of AR-glass, carbon or basalt rovings. The high tensile strength of the rovings and their high resistance against corrosion enable to construct light, durable and cost effective optimal thin walled structural elements. The use of high strength and electrically conductive carbon rovings, enables the rovings to serve simultaneously as the reinforcement system and as the sensory agent. The self-sensory concept of the carbon rovings was investigated, in the literature, for SHM purposes for detecting mechanical loading and integrative strain and cracking.

The studies in the literature proved the feasibility and potential of the self-sensory carbon rovings by correlating the structural responses with the measured electrical resistance (ER) or voltage changes and accordingly, were usually based on direct current (DC) electrical circuits.  The current study aims to further characterize the electrical response and to understand the various electrical mechanism that could control the smart sensory system. Such an investigation is mainly relevant in case of rovings made of thousands of conductive filaments that do not behave as an ideal resistor and may reflect other electrical effects than ER changes. Using alternating current (AC) measurements, the current study demonstrates that the electrical characterization of the carbon rovings includes ER and inductance effects that are influenced by the cement matrix. An experimental investigation is performed to characterize the electrical properties of the carbon roving and demonstrate their capabilities in identifying the structural health. It is demonstrated that a sensory carbon roving is characterized by a RL electrical circuit and its inductance and resistance can be measured by the electrical response spectrum of the impedance.

To demonstrate its SHM capabilities, a TRC beam is monotonically loaded, and the electrical signals of the carbon roving are monitored along the entire loading process. Along with the electrical signal of the sensory carbon roving, the monitoring system includes the load, the mid-deflection and the strain profile by DIC (digital image correlation) technique. Such an investigation enables to correlate between the electrical signals, the strain and the crack distribution along the beam. The study demonstrates that the micro- and macro-structural responses can be corelated by both ER and inductance changes. It further demonstrates that each electrical quantity is more dominant at another structural state. Such an investigation opens new directions in the development of robust, sensitive and consistent smart monitoring system.

 

Presenting Author: Mahdi Gaben Techinon

Authors:

Mahdi Gaben Techinon
Yiska Goldfeld Technion