Electromechanical modelling of a new class of nanocomposite cement-based sensors for structural health monitoring

Abstract

This work focuses on the analysis of a new nanocomposite cement-based sensor (carbon nanotube cementbased sensor), for applications in vibration-based structural health monitoring of civil engineering structures. The sensor is constituted of a cement paste doped with multi-walled carbon nanotubes, so that mechanical deformations produce a measurable change of the electrical resistance. Prior work of some of the authors has addressed the fabrication process, dynamic behaviour and implementation to full-scale structural components. Here, we investigate the effectiveness of a linear lumped-circuit electromechanical model, in which dynamic sensing is associated with a strain-dependent modulation of the internal resistance. Salient circuit parameters are identified from a series of experiments where the distance between the electrodes is parametrically varied. Experimental results indicate that the lumped-circuit model is capable of accurately predicting the step response to a voltage input and its steady-state response to a harmonic uniaxial deformation. Importantly, the model is successful in anticipating the presence of a superharmonic component in sensor's output. KeywordsCarbon nanotubes, electromechanical model, nanotechnology, smart materials, smart sensors, structural health monitoring nanotubes, so that mechanical deformations produce a measurable change of the electrical resistance.Prior work of some of the authors has addressed the fabrication process, dynamic behaviour, and implementation to full-scale structural components. Here, we investigate the effectiveness of a linear lumped-circuit electromechanical model, in which dynamic sensing is associated with a straindependent modulation of the internal resistance. Salient circuit parameters are identified from a series of experiments where the distance between the electrodes is parametrically varied. Experimental results indicate that the lumped-circuit model is capable of accurately predicting the step response to a voltage input and its steady-state response to a harmonic uniaxial deformation. Importantly, the model is successful in anticipating the presence of a superharmonic component in sensor's output.

Towards smart concrete for smart cities: Recent results and future application of strain-sensing nanocomposites

“…The study was based on the piezoresistive effect of pull-out of fibers that passed through micro-cracks. The ability of the material to self-detect cracks and strain was due to the modification of the characteristics of electrical paths developing within the material [36][37][38][39] .…”

“…Through resistance or electrical resistivity changes, deformation or tension state can be estimated. Literature suggests that the electrical behavior of cement-based sensors with carbon nanotubes can be modeled through a system of resistors and capacitors [36][37][38] ( Figure 5). The relationship between electrical resistance (∆R) and axial strain (ε) is assumed to be linear for small e, as commonly modeled in electrical strain gauges [38] :…”

“…(2) Figure 5 shows the electrical circuit proposed by the authors [38] , where C 0 is the internal capacitance and R c represents contact resistance. With an applied compressive axial load, a mechanical deformation occurs, the distance between the electrodes d 0 changes, and the change in the electrical properties of the material can be measured.…”

Static and Dynamic Strain Monitoring of Reinforced Concrete Components through Embedded Carbon Nanotube Cement-Based Sensors

“…Although several studies were recently devoted to investigating challenges related to the dispersion of the conductive nanoparticles in the cement matrix [24,25], the fabrication of nanocomposites with different amounts of fillers [26,27], and electromechanical testing [28][29][30], the repeatability and accuracy of the electrical behavior upon dynamic sensing still require in-depth investigations. The authors have researched a new cement-based sensor doped with multiwalled carbon nanotubes, termed carbon nanotube cement-based sensor (CNTCS) [15,24,31,32]. The CNTCSs were fabricated with different types of cement matrices (pastes, mortars, and concretes) and various amounts of carbon nanoinclusions.…”

An Experimental Study on Static and Dynamic Strain Sensitivity of Smart Concrete Sensors Doped with Carbon Nanotubes for SHM of Large Structures

“…This is a powerful advantage over off-the-shelf sensing technologies that are known to have limited scalability due to economic and or technical constraints [29,30]. The self-sensing ability of cement-based materials or sensors is obtained through mapping variations in strain to variations in electrical characteristics of the material such as electrical resistivity or conductivity [31][32][33][34][35][36][37][38][39]. Literature demonstrates that suitable fillers for cementitious matrices yielding self-sensing materials are carbon-based particles of short, micro or nano sizes [40][41][42][43].…”