A universal NDT method for examination of low energy impact damage in CFRP with the use of TLC film

• Published in: Nondestructive testing and evaluation Vol. 33; no. 3; pp. 315 - 328
• Main Authors: Strugała, G., Klugmann, M., Landowski, M., Szkodo, M., Mikielewicz, D.
• Format: Journal Article
• Language: English
• Published: Abingdon Taylor & Francis 03-07-2018; Taylor & Francis Ltd
• Subjects: Carbon fiber reinforced plastics; Composite materials; Damage detection; Destructive testing; Fiber reinforced polymers; Impact damage; Liquid crystals; Low cost; Nondestructive testing; Radiography; Recording; Recording equipment; Scattering; thermal imaging; Thermography
• ISSN: 1058-9759; 1477-2671
• DOI: 10.1080/10589759.2018.1428323

The article presents an attempt to use a sheet of laminated thermochromic liquid crystal film (TLC film) for non-destructive testing of the impact damage (energy values: 1J, 2J, 3J and 4J) in carbon fibre-reinforced polymer (CFRP). This is a new, alternative NDT approach based on the thermo-optical effect. The main advantages of this method are a) the low cost of TLC film, b) the low cost of recording devices due to the usage of conventional digital recording equipment and c) the low requirements for tests. The TLC film method was compared with two other conventional NDT methods: computer radiography (CR) and active thermography (thermographic camera). The scatter of results regarding the average crack length (TLC film and active thermography) was ±5% in relation to the CR method. The damage area (impact energy 2J to 4J) showed a similar shape (TLC film vs active thermography) and the scatter of results for the TLC film was ±2% in relation to the active thermography method. Only the CR detected the damage caused by 1J impact energy. The comparative studies have proven that the described method (TLC film) is a full-fledged and accurate tool for NDT method for the diagnosis of impact damage in CFRP.