Accurate and efficient internal deformation measurement of multiphase/porous materials via segmentation-aided digital volume correlation.

Abstract

In using the regular subvolume-based digital volume correlation (R-DVC) method, calculation points should be defined at the real material phase, and the local deformation within the interrogated subvolumes is assumed to be continuous. However, this basic assumption in R-DVC analysis is often violated when measuring the deformation near the interface when dealing with multiphase materials (including porous materials) or contact problems. This is because discontinuous deformation always presents in the calculation points located at the vicinity of interfaces of various phases. All these factors lead to increased measurement error and/or meaningless calculation burdens when using R-DVC. To address these issues, we propose a segmentation-aided DVC (S-DVC) for accuracy-enhanced internal deformation analysis near the interface. The presented S-DVC first divides the reference volume image into different portions according to the distinct gray scales within different material phases (or background) or objects. Based on the segmented reference volume image, we can ensure that subvolumes only contain the voxels from the same material phase/object and exclude other phases/objects. As such, the error due to undermatched shape function can be minimized and meaningless DVC calculation can be avoided. The accuracy, efficiency, and practicality of S-DVC over R-DVC are validated by a simulated compression test of nodular cast iron (multiphase material) and a real compression experiment of 3D printed polymer (porous material).