Promises and challenges of using electrical resistance change to detect damage in carbon fibre composite laminates
Topic(s) : Material and Structural Behavior - Simulation & Testing
Co-authors :
Jose David ACOSTA CORREA (UNITED KINGDOM), Andrew HAMILTON , Meisam JALALVANDAbstract :
Monitoring the structural health of composite materials, specifically carbon fibre composites (CFRP), can be effectively achieved by assessing damage via electrical resistance change. Referred to as the electrical resistance change method (ERC), this approach is a relatively straightforward and non-intrusive means of detecting damage in CFRP. The ERC method promises to detect damage on large structures such as aircraft, bridges, ships, among others. Nevertheless, one of the main challenges is the high number of electrodes used to detect damage and the damage size that can be detected in a determined area.
Although the damage has been successfully detected, high number of electrodes on a relatively small area to detect small cracks makes this approach very difficult to implement on a full-scale structure. Some studies have used multiple electrodes, establishing a minimum detectable damage size according to a sensing area where it is possible to detect damage. Idris et al. (Idris et al., 2021, Funct. comp. and Struct., 3: 0-19) found that the minimum detectable damage area for a woven carbon plate of 113 mm X 84 mm was about 0.04% of the sensing area using fourteen electrodes and an electrode separation of 26 mm in the X-direction and 16 mm in the Y-direction. On the other hand, Cagáň (Cagáň, 2017, Struct. Health. Monit., 16, 129–141) concluded that using nineteen electrodes on a 100 mm diameter circular plate, the minimum detectable damage area was 0.1% of the total sensing area. Additionally, the data to process and the wiring increase with the number of electrodes to sense damage, increasing the weight and cost of the SHM system and compromising its attractiveness.
The aim of this works is to determine the minimum number of electrodes to detect damage and the minimum crack length that can be detected using the ERC method. This reaerch studies experimentally and numerically, using the finite element method (FEM), the electrical resistance changes due to the presence of a crack in different CFRP laminates such as unidirectional (UD), cross-ply (CP) [0/90], 45-angle ply (45AP) [45/-45] and quasi-isotropic (QI) [0/90/45/-45]S. Four electrodes are placed on the corners of the samples, and different crack lengths and locations are evaluated.
This investigation shows that only four electrodes are required to detect a crack, and the minimum detectable crack length would depend on the monitored area. It was found that the minimum detectable crack length for a central crack in a CP, 45AP and QI laminates is 27 % of the monitored area, while for a UD laminate is 93 %. Alternatively, the monitored area could be scaled to achieve a required detectable crack length and an array of 4 X 4 electrodes patterned over the area of interest. In conclusion, a small monitored area with four electrodes is required to detect a small crack, and this basic electrode arrangement can easily be scaled and patterned to achieve specific health monitoring requirements.
Although the damage has been successfully detected, high number of electrodes on a relatively small area to detect small cracks makes this approach very difficult to implement on a full-scale structure. Some studies have used multiple electrodes, establishing a minimum detectable damage size according to a sensing area where it is possible to detect damage. Idris et al. (Idris et al., 2021, Funct. comp. and Struct., 3: 0-19) found that the minimum detectable damage area for a woven carbon plate of 113 mm X 84 mm was about 0.04% of the sensing area using fourteen electrodes and an electrode separation of 26 mm in the X-direction and 16 mm in the Y-direction. On the other hand, Cagáň (Cagáň, 2017, Struct. Health. Monit., 16, 129–141) concluded that using nineteen electrodes on a 100 mm diameter circular plate, the minimum detectable damage area was 0.1% of the total sensing area. Additionally, the data to process and the wiring increase with the number of electrodes to sense damage, increasing the weight and cost of the SHM system and compromising its attractiveness.
The aim of this works is to determine the minimum number of electrodes to detect damage and the minimum crack length that can be detected using the ERC method. This reaerch studies experimentally and numerically, using the finite element method (FEM), the electrical resistance changes due to the presence of a crack in different CFRP laminates such as unidirectional (UD), cross-ply (CP) [0/90], 45-angle ply (45AP) [45/-45] and quasi-isotropic (QI) [0/90/45/-45]S. Four electrodes are placed on the corners of the samples, and different crack lengths and locations are evaluated.
This investigation shows that only four electrodes are required to detect a crack, and the minimum detectable crack length would depend on the monitored area. It was found that the minimum detectable crack length for a central crack in a CP, 45AP and QI laminates is 27 % of the monitored area, while for a UD laminate is 93 %. Alternatively, the monitored area could be scaled to achieve a required detectable crack length and an array of 4 X 4 electrodes patterned over the area of interest. In conclusion, a small monitored area with four electrodes is required to detect a small crack, and this basic electrode arrangement can easily be scaled and patterned to achieve specific health monitoring requirements.