Damage Quantification via Digital Volume Correlation with Heterogeneous Mechanical Regularization: Application to an In situ Meso-Flexural Test on Mortar

Abstract

Background. The mechanical response and damage mechanisms of het-1 erogeneous cementitious materials result from the mechanical properties of their 2 A. Tsitova, F. Bernachy-Barbe (formerly), B.

Identification of microscale fracture models for mortar with in-situ tests

“…More details on the experimental set-up, protocol and XCT acquisition parameters are provided in Ref. [68]. In test B, the load was centered and the inclusions in the notch-loading pin plane were relatively small.…”

“…Before the in situ test, a high quality scan of the central part of the microbeam was acquired with a 5.3 µm / vx resolution using the same CT system. Then, the procedures of microstructure segmentation and heterogeneous FE mesh generation, which are detailed in [68], were applied to samples A and B. In order to model the entire specimen in mechanical simulations, homogeneous regions with four-noded tetrahedral elements were added to the microstructure-based mesh, denoted as Region Of Interest (ROI), with the open-source python library…”

“…The segmented microstructures were used in the Finite Element (FE) discretization, which consisted of a microstructure-based mesh in the crack propagation zone and homogeneous zones for intact parts of the beam. Furthermore, experimental kinematic fields were measured by processing the reconstructed volumes via DVC [68]. The measured displacements were used as kinematic BCs to simulate two three-point flexural tests.…”

“…In regularized DVC, the linear elastic behavior is enforced locally by the introduction of a mechanical penalty Φ m term based on the equilibrium gap[80; 81; 82]. The global minimization is then performed on the weighted sum of the normalized cost functions Φ2 c + w m Φ2 m (for more details, see[68]). The weight w m is proportional to a regularization length raised to the fourth power ℓ 4 reg .…”

Digital Volume Correlation for large deformations of soft tissues: Pipeline and proof of concept for the application to breast ex vivo deformations

“…In the present study, the ROI covered three different materials (i.e., soft tissue, cartilage, and bones). To account for the fact that their elastic properties were very different, heterogeneous regularization was utilized [43]. As a consequence, each element e was assigned an elastic contrast C e whose value was the ratio of the Young's modulus of the phase it belonged to divided by that of the soft tissue.…”