Analytical Model Approximation for Defect Classification in Fiberglass Composites Inspected by Long-Pulse Thermography

Author(s):  
Roberto Marani ◽  
Davide Palumbo ◽  
Giuseppe Bono ◽  
Grazia Cicirelli ◽  
Umberto Galietti ◽  
...  
2021 ◽  
Vol 24 (suppl 2) ◽  
Author(s):  
José Jerônimo Rabelo Faria ◽  
Alfredo Rocha de Faria

2021 ◽  
Vol 8 ◽  
Author(s):  
Murniwati Anwar ◽  
Faizal Mustapha ◽  
Mohamed Thariq H. Sultan ◽  
Izhal A. Halin ◽  
Mohd N. Abdullah ◽  
...  

The demand for composite fiber material is significantly high due to its excellent mechanical properties and its use in various industries. Recently, with the increasing awareness of environmental issues, researchers are now focusing more on eco-friendly and green materials. A biocomposite offers a good balance of strength and stiffness ratio, bending and membrane mechanical properties, balanced thermal distortion stability, reduced weight and cost, improved fatigue resistance, reduced notch sensitivity, and, comparatively, better performance than synthetic composites. Yet, due to the complex anisotropy of the composite material, the inspection and detection of inner defects become a challenge. Long-pulse thermography is one of the non-destructive evaluations (NDEs) used to detect defects in composite materials. However, very limited research has been carried out on the usage of a low-resolution infrared camera to perform defect or damage inspection on flax composite laminates. In this paper, an experimental setup of a long pulse thermography system using low-resolution infrared camera was performed on flax bio-composite to identify impact and lightning damage. The result highlights that with control parameters, a low-resolution infrared camera has the capability to capture the lightning and impact defects of flax biocomposites using the long-pulse thermography system. An image processing method is then applied to the defect to improve the quality of defect detection and reduce background noise.


2021 ◽  
Vol 11 (20) ◽  
pp. 9545
Author(s):  
Friederike Jensen ◽  
Marina Terlau ◽  
Michael Sorg ◽  
Andreas Fischer

Initial defects, for example, those occurring during the production of a rotor blade, encourage early damages such as rain erosion at the leading edge of wind turbine rotor blades. To investigate the potential that initial defects have for early damage, long-pulse thermography as a non-destructive and contactless measurement technique is applied to a strongly curved and coated test specimen for the first time. This specimen is similar in structural size and design to a rotor blade leading edge and introduced with sub-surface defects whose diameters range between 2mm and 3.5mm at depths between 1.5mm and 2.5mm below the surface. On the curved and coated test specimen, sub-surface defects with a depth-to-diameter ratio of up to 1.04 are successfully detected. In particular, defects are also detectable when being observed from a non-perpendicular viewing angle, where the intensity of the defects decreases with increasing viewing angle due to the strong surface curvature. In conclusion, long-pulse thermography is suitable for the detection of sub-surface defects on coated and curved components and is therefore a promising technique for the on-site application during inspection of rotor blade leading edges.


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