Fracture toughness testing using photogrammetry and digital image correlation

• Autor(a) principal: Hao Kan, Wen
• Data de Publicação: 2018
• Outros Autores: Albino, Carlos, Dias-da-Costa, Daniel, Dolman, Kevin, Lucey, Timothy, Tang, Xinhu, Cairney, Julie, Proust, Gwénaëlle
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10316/107780; https://doi.org/10.1016/j.mex.2018.09.012
• topic: Digital image correlation (DIC); Photogrammetry; Metal matrix composite; High chromium white cast iron; Fracture toughness

Digital image correlation (DIC) is an optical technique commonly used for measuring displacement fields by tracking artificially applied random speckle patterns, which can sometimes be a problem for tracking small-scale displacements. DIC is particularly useful for tracking the crack mouth opening displacement (CMOD) of a notched metallic specimen subjected to three-point bending for fracture toughness determination because the edges of the notch provide the required textural features for DIC without the need for speckle patterns. This simplifies the set-up process as the specimen and stage geometries do not need to account for the placement of a strain gauge. To enhance the accuracy of DIC, this study then successfully downscaled a photogrammetry technique commonly used to track crack propagation in large scale concrete tests so that the pixel coordinates of the captured images can be automatically related to their real-world coordinates, allowing for small scale displacements to be accurately tracked.