Application of the bulge test combined with 3D-DIC for biaxial characterization of PLA films and defect detection

The bulge test is a versatile mechanical testing technique widely applied in materials science, engineering, and biomedical research to understand the mechanical behavior of materials and structures. In this study, PLA blown films were characterized through the bulge test, and the corresponding properties were compared to those obtained from uniaxial t!esting. To achieve more accurate and precise deformation measurements, 3D digital image correlation (3D-DIC) was used, offering superior capabilities in terms of accuracy, precision, and non-destructive testing. This technique can detect defects such as cracks, voids, and delamination in materials and structures. During the bulge testing, 3D-DIC was utilized to analyze the strain field evolution within the test sample and identify regions of reduced film thickness. Notably, the results indicated zones with strain concentration aligned parallel to the film machine direction, suggesting localized thickness reduction in those areas.