Enhanced health monitoring of fibrous composites with aligned carbon nanotube networks and electrical impedance tomography

2012 ◽  
Author(s):  
T. Tallman ◽  
F. Semperlotti ◽  
K. W. Wang
Keyword(s):  
Carbon Nanotube ◽  
Electrical Impedance Tomography ◽  
Health Monitoring ◽  
Electrical Impedance ◽  
Fibrous Composites ◽  
Impedance Tomography ◽  
Carbon Nanotube Networks

scholarly journals Evaluation of the Damage Detection Characteristics of Electrical Impedance Tomography

2013 ◽  
Author(s):  
Bryan R. Loyola ◽  
Luciana Arronche ◽  
Marianne LaFord ◽  
Valeria La Saponara ◽  
Kenneth J. Loh
Keyword(s):  
Thin Film ◽  
Electrical Conductivity ◽  
Carbon Nanotube ◽  
Electrical Impedance Tomography ◽  
Health Monitoring ◽  
Electrical Impedance ◽  
Fiber Reinforced Polymer ◽  
Impedance Tomography ◽  
Structural Health ◽  
Reinforced Polymer

In the United States, many civil, aerospace, and military aircraft are nearing the end of their service life. Many of these service life predictions were determined by models that were created at the time of the design of the structure, possibly decades ago. As a precaution, these structures are inspected on a regular basis with techniques that tend to be expensive and laborious, such as tear-down inspections of aircraft. To complicate matters, new complex materials have been incorporated in recent structures to take advantage of their desirable properties, but these materials sustain damage in a manner that is different from that of past monolithic materials. One example is fiber-reinforced polymer (FRP) composites, which are heterogeneous, direction-dependent, and tend to manifest damage internal to their laminate structure, thus making the detection of this damage nearly impossible. For these reasons, numerous groups have focused on developing sensors that can be applied to or embedded within these structures to detect this damage. Some of the most promising of these approaches include using piezoelectric materials as passive or active ultrasonic sensors and actuators, fiber optic-based sensors to measure strain and detect cracking, and carbon nanotube-based sensors that can detect strain and cracking. These are mostly point-based sensors that are accurate at the location of application but require interpolative methods to ascertain the structural health elsewhere on the structure. To conduct direct damage detection across a structure, we have coupled the ability to deposit a carbon nanotube thin film across large substrates with a spatially distributed electrical conductivity measurement methodology called electrical impedance tomography. As indicated by previous research on carbon nanotube thin films, the electrical conductivity of these films changes when subjected to strain or become damaged. Our structural health monitoring strategy involves monitoring for changes in electrical conductivity across an applied CNT thin film, which would indicate damage. In this work, we demonstrate the ability of the Electrical Impedance Tomography (EIT) methodology to detect, locate, size, and determine severity of damage from impact events subjected to glass fiber-reinforced polymer composites. This will demonstrate the value and effectiveness of this next-generation structural health monitoring approach.

On the inverse determination of displacements, strains, and stresses in a carbon nanofiber/polyurethane nanocomposite from conductivity data obtained via electrical impedance tomography

2017 ◽  
Vol 28 (18) ◽  
pp. 2617-2629 ◽  
Author(s):  
TN Tallman ◽  
S Gungor ◽  
GM Koo ◽  
CE Bakis
Keyword(s):  
Structural Health Monitoring ◽  
Electrical Impedance Tomography ◽  
Health Monitoring ◽  
Electrical Impedance ◽  
Carbon Nanofiber ◽  
Constitutive Relations ◽  
Full Potential ◽  
Conductivity Data ◽  
Impedance Tomography ◽  
Structural Health

Carbon nanofiller-modified composites possess extraordinary potential for structural health monitoring because they are piezoresistive and therefore self-sensing. To date, considerable work has been done to understand how strain affects nanocomposite conductivity and to utilize electrical impedance tomography for detecting strain or damage-induced conductivity changes. Merely detecting the occurrence of mechanical effects, however, does not realize the full potential of piezoresistive nanomaterials. Rather, knowing the mechanical state that results in the observed conductivity changes would be much more valuable from a structural health monitoring perspective. Herein, we make use of an analytical piezoresistivity model to inversely determine the displacement field of a strained carbon nanofiber/polyurethane nanocomposite from conductivity changes obtained via electrical impedance tomography. From the displacements, kinematic and constitutive relations are used to calculate strains and stresses, respectively. A commercial finite element simulation is then used to validate the accuracy of these predictions. These results concretely demonstrate that it is possible to inversely determine displacements, strains, and stresses from conductivity data thereby enabling unprecedented insight into the mechanical response of piezoresistive nanofiller-modified materials and structures.

A novel composite gold/gold nanoparticles/carbon nanotube electrode for frequency-stable micro-electrical impedance tomography

2020 ◽  
Vol 31 (13) ◽  
pp. 10803-10810
Author(s):  
Zahra Rezanejad Gatabi ◽  
Raheleh Mohammadpour ◽  
Javad Rezanejad Gatabi ◽  
Mehri Mirhoseini ◽  
Pezhman Sasanpour
Keyword(s):  
Gold Nanoparticles ◽  
Carbon Nanotube ◽  
Electrical Impedance Tomography ◽  
Electrical Impedance ◽  
Impedance Tomography

Damage Sensitivity and Multiple Damage Detection in Glass Fiber/Epoxy Laminates With Carbon Black Filler via Electrical Impedance Tomography

2014 ◽  
Author(s):  
T. N. Tallman ◽  
K. W. Wang
Keyword(s):  
Carbon Black ◽  
Damage Detection ◽  
Glass Fiber ◽  
Electrical Impedance Tomography ◽  
Health Monitoring ◽  
Electrical Impedance ◽  
Fiber Reinforced Polymers ◽  
Impedance Tomography ◽  
The Matrix ◽  
Matrix Damage

Utilizing conductivity changes to locate matrix damage in glass fiber reinforced polymers (GFRPs) manufactured with nanocomposite matrices is a promising avenue of composite structural health monitoring (SHM) with the potential to ensure unprecedented levels of safety. Nanocomposites depend on the formation of well-connected nanofiller networks for electrical conductivity. Therefore, matrix damage that severs the connection between nanofillers will manifest as a local change in conductivity. This research advances state of the art conductivity-based SHM by employing electrical impedance tomography (EIT) to locate damage-induced conductivity changes in a glass fiber/epoxy laminate manufactured with carbon black (CB) filler. EIT for damage detection is characterized by identifying the lower threshold of through-hole detection and demonstrating the capability of EIT to accurately resolve multiple through holes. It is found that through holes as small as 3.18 mm in diameter can be detected, and EIT can detect multiple through holes. However, sensitivity to new through holes is diminished in the presence of existing through holes unless a damaged baseline is used. These research findings demonstrate the considerable potential of conductivity-based health monitoring for GFRP laminates with conductive networks of nanoparticles in the matrix.

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