Perpustakaan Digital ITB

This paper aims to investigate and compare different application methods for speckle patterns to be used in a large deformation digital image correlation analysis. This research is done to further the accuracy and reliability of DIC analysis so that its utility can be advanced in the field of stress-strain analysis. The experiment will utilize four different methods of speckle pattern application which are: spray paint, water transfer printing, laser engraving, and laser engraving with anodizing. A tensile test will be done on the treated specimen and the entirety of the testing process will be captured by a camera and processed by a code written with MATLAB. The code will implement a feature extraction algorithm called SURF (Speeded Up Robust Features) to identify the number of features on each frame. The higher number of identified feature will be correlated to the method’s accuracy in a DIC analysis environment. Results indicate that laser engraving method and its anodized counterpart shows the most promise that is attributed to its subtractive method and accuracy in applying the pattern. Spray paint is the most practical however its result is mediocre at best due to its inability to control the applied pattern. Lastly water transfer printing shows that it is the least viable due to its inherent trait of the pattern prematurely peeling of off the specimen. In conclusion laser engraving is the most reliable method boasting high average feature counts but falls short on precision, whilst its anodized counterpart is more precise but has an innate problem of colour degradation and glare if not treated optimally.