O estudante Bernardo Cassimiro Fonseca de Oliveira, orientado pelo Prof. Armando Albertazzi Gonçalves Junior, Dr. Eng. e coorientado pelos Prof. Gustavo Daniel Donatelli, Dr. Eng., e Prof. Crhistian Raffaelo Baldo, Dr. Eng. (UFABC), defenderá sua tese na próxima terça-feira (20/08) às 10h em sala de aula do Labmetro, na Fundação CERTI. A defesa é vinculada ao Programa de Pós-Graduação em Engenharia Mecânica. A sala tem capacidade para 40 pessoas. Para entrar, basta dizer na recepção que irá assistir à essa defesa.
Título: “Inspection of impact damages in carbon fibre reinforced plastic plates through the fusion of images from optical lock-in thermography and optical square-pulse shearography techniques”
Resumo:
The preservation of the environment has been more in evidence lately, due to alarming study results about the effects of gas emissions in the atmosphere. The weight reduction is a way to enhance the performance of gasemitting machines. An interesting alternative to reduce weight is the replacement of metallic alloys for composite materials, such as the carbon fibre reinforced plastics (CFRPs), due to their capability of such materials to provide a mechanical behaviour comparable to the one of metals but with a fraction of their weights. However, composite materials are typically anisotropic, which enhances substantially the mechanical analysis complexity of damages such as the ones caused by impacts. This leads to many dangerous scenarios since the defects caused by impacts are difficult to visually detect and many are invisible on the impacted side.
Non-destructive testing (NDT) methods are integrity inspections capable of detect such abnormalities. But there is no NDT method capable of reliably detect all abnormalities under all conditions in all materials. In the case of inspecting composites in order to look for damages caused by impacts, ultrasound is the most complete technology. However, ultrasound may present issues regarding the surface of the inspected part, its mechanical properties and may need physical contact. Shearography and thermography are contactless NDT methods that are widely used for composite inspection and whose inspection may be cheaper than the ultrasound one, but they have different sensitivities regarding the effect of impacts on CFRP parts, which can lead to misinterpretations of their results. Combining such NDT methods to achieve reliable, cheaper results can be consequently interesting. Data fusion tools provide promising outcomes when it comes to combining data from two or more sources in a synergistical way. In this work, it is proposed the combined use of active lock-in thermography and square pulse shearography to inspect impact damages stemming from different energies in
CFRP plates, from barely visible defects to perforation stages. Several combinations of different image processing tools were developed and tested to evaluate which is the best option for fusing and segmenting impact damages in image coming from these two NDT techniques, using results from ultrasound as reference.
The results indicated that the fusion of the proposed NDT methods is technically effective to achieve inspection results closer to the ones provided by the reference technology and it can be seen as a potential alternative for industries that relies on ultrasound as the main NDT technique.
Palavras-chave: thermography, shearography, image fusion, lock-in loading, carbon fibre reinforced plastics, non-destructive testing, impact damage.