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

Abstract

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.