Damage detection in non-planar carbon fiber-reinforced polymer laminates via electrical impedance tomography with surface-mounted electrodes and directional sensitivity matrices
Damage detection in non-planar carbon fiber-reinforced polymer laminates via electrical impedance tomography with surface-mounted electrodes and directional sensitivity matrices
- Composites Science and Technology, 224, p.109429, 2022 .
Carbon fiber reinforced polymers (CFRPs)have emerged as promising alternatives to traditional metals and alloys in weight-conscious applications such as aerospace due to their superior strength-to-weight properties. However, these materials are vulnerable to complex and difficult-to-predict sub-surface damages. Therefore, damage detection modalities are important for assuring the safety of CFRP-based structures and components. Particularly for in-service structural health monitoring (SHM), it would be desirable to utilize an inherent property of these materials, such as electrical conductivity, as a means of detecting and localizing damages. In this respect, electrical impedance tomography (EIT)is a promising SHM modality. Studies to-date involving the application of EIT to CFRPs are limited due to the challenges associated with high electrical anisotropy. Furthermore, most studies have only considered flat laminates with unrealistic edge-placed electrodes. In this paper, we advance the state of the art by studying the application of EIT to non-planar CFRP geometries using surface-mounted electrodes. Additionally, we present a modified EIT sensitivity matrix formulation which intrinsically incorporates the electrical anisotropy of the material by forming the sensitivity matrix via three approaches - with respect to i)a scalar multiple of the conductivity tensor, ii)the in-plane conductivity, and iii)the through-thickness conductivity. It was found that both through-hole and impact damages can be adeptly identified with a combination of surface-mounted electrodes and a sensitivity matrix formed with respect to either a scalar multiple of the conductivity tensor or the in-plane conductivity. The results presented here are an important step towards the transition of EIT-based diagnostics to actual CFRP structures.
CARBON FIBER REINFORCED POLYMER (CFRP)
DAMAGE DETECTION
ELECTRICAL IMPEDANCE TOMOGRAPHY
STRUCTURAL HEALTH MONITORING
ELECTRICAL ANISOTROPY
Carbon fiber reinforced polymers (CFRPs)have emerged as promising alternatives to traditional metals and alloys in weight-conscious applications such as aerospace due to their superior strength-to-weight properties. However, these materials are vulnerable to complex and difficult-to-predict sub-surface damages. Therefore, damage detection modalities are important for assuring the safety of CFRP-based structures and components. Particularly for in-service structural health monitoring (SHM), it would be desirable to utilize an inherent property of these materials, such as electrical conductivity, as a means of detecting and localizing damages. In this respect, electrical impedance tomography (EIT)is a promising SHM modality. Studies to-date involving the application of EIT to CFRPs are limited due to the challenges associated with high electrical anisotropy. Furthermore, most studies have only considered flat laminates with unrealistic edge-placed electrodes. In this paper, we advance the state of the art by studying the application of EIT to non-planar CFRP geometries using surface-mounted electrodes. Additionally, we present a modified EIT sensitivity matrix formulation which intrinsically incorporates the electrical anisotropy of the material by forming the sensitivity matrix via three approaches - with respect to i)a scalar multiple of the conductivity tensor, ii)the in-plane conductivity, and iii)the through-thickness conductivity. It was found that both through-hole and impact damages can be adeptly identified with a combination of surface-mounted electrodes and a sensitivity matrix formed with respect to either a scalar multiple of the conductivity tensor or the in-plane conductivity. The results presented here are an important step towards the transition of EIT-based diagnostics to actual CFRP structures.
CARBON FIBER REINFORCED POLYMER (CFRP)
DAMAGE DETECTION
ELECTRICAL IMPEDANCE TOMOGRAPHY
STRUCTURAL HEALTH MONITORING
ELECTRICAL ANISOTROPY