Synchronous application of DIC and DVC techniques for the global-local characterization of carbon fiber-reinforced composite laminates

DIC is capable of continuously measuring the global deformation behavior of a specimen because its scanning can be done quickly over a wider observation area. While the DIC information is limited to the surface on which a speckle pattern is applied, DVC can compute three-dimensional strain fields inside a material. However, DVC data can be obtained over a smaller region at a limited number of load levels. Here, the DIC and DVC techniques are simultaneously utilized for the first time. The previous in situ test setup of the authors based on synchrotron radiation computed tomography was modified to add the DIC capability. The in situ testbed was installed with a CCD camera with blue lighting to obtain images for DIC analysis. The opaque tubular frame of a micro-tensile stage was newly fabricated with a transparent material causing minimal optical distortion. The qualities of speckle pattern images obtained through the transparent tube were carefully evaluated. The combination of the DVC and DIC techniques was demonstrated with an open-hole tensile test. The global and local failure progression of the composite was non-destructively characterized. Especially, a load-displacement curve without machine compliance was obtained because the deformation of the specimen could be directly measured owing to the DIC technique. The resolutions of DVC and DIC in the presented study were 0.65 μm and 2.27 μm, respectively. This specification is expected to provide unprecedented results that can truly validate multi-scale simulation models. • DIC and DVC techniques were simultaneously applied for the first time to characterize the global and local behavior of a carbon fiber-reinforced composite material. • The combination of synchrotron radiation computed tomography with the DIC and DVC techniques was successfully applied to characterize the failure progression of an open-hole tension specimen. • Owing to the DIC technique, the typical machine compliance issue of most miniature tensile stages is resolved because the deformation of a sample can be directly measured. • The inspection area of DIC was 6 mm by 5 mm and the resolution of DVC was 0.65 μm. These specifications are expected to provide unprecedented results that can truly validate multi-scale simulation models with a global load-displacement curve having no machine compliance.