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19 results on '"Roubin, E."'

1. DIC Challenge 2.0: Developing Images and Guidelines for Evaluating Accuracy and Resolution of 2D Analyses: Focus on the Metrological Efficiency Indicator

Author

Reu, P. L., Blaysat, B., Andó, E., Bhattacharya, K., Couture, C., Couty, V., Deb, D., Fayad, S. S., Iadicola, M. A., Jaminion, S., Klein, M., Landauer, A. K., Lava, P., Liu, M., Luan, L. K., Olufsen, S. N., Réthoré, J, Roubin, E., Seidl, D. T., Siebert, T., Stamati, O., Toussaint, E., Turner, D., Vemulapati, C. S. R., Weikert, T., Witz, J. F., Witzel, O., and Yang, J.

Published
2022
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12. Multi-scale failure for heterogeneous materials: link with morphological modeling – COMPLAS XI

Author

Roubin, E., Bodgan, M., Colliat, J.B., Roubin, E., Bodgan, M., and Colliat, J.B.

Abstract

A 3D meso-scale model for failure of heterogeneous quasi-brittle materials is presented. At such scale, concrete can be represented as an heterogenous material with two phases, where aggregates are included within the concrete. The model problem of heterogeneous materials that is adressed in detail here is based, on the one hand, on FE models with embedded discontinuities and, on the other hand, on a morphological representation using Gaussian or Gaussian related random field excursion sets.

Published
2011

17. DIC Challenge 2.0: Developing Images and Guidelines for Evaluating Accuracy and Resolution of 2D Analyses

Author

Reu, P. L., Blaysat, B., Ando, E., Bhattacharya, K., Couture, C., Couty, V., Deb, D., Fayad, S. S., Iadicola, M. A., Jaminion, S., Klein, M., Landauer, A. K., Lava, P., Liu, M., Luan, L. K., Olufsen, S. N., Rethore, J., Roubin, E., Seidl, D. T., Siebert, T., Stamati, O., Toussaint, E., Turner, D., Vemulapati, C. S. R., Weikert, T., Witz, J. F., Witzel, O., and Yang, J.

Subjects
dic, displacement, noise, metrology, algorithm, digital image correlation, errors, dic challenge, full-field measurement, interpolation
Abstract

Background The DIC Challenge 2.0 follows on from the work accomplished in the first Digital Image Correlation (DIC) Challenge Reu et al. (Experimental Mechanics 58(7):1067, 1). The second challenge was required to better quantify the spatial resolution of 2D-DIC codes. Objective The goal of this paper is to outline the methods and images for the 2D-DIC community to use to evaluate the performance of their codes and improve the implementation of 2D-DIC. Methods This paper covers the creation of the new challenge images and the analysis and discussion of the results. It proposes a method of unambiguously defining spatial resolution for 2D-DIC and explores the tradeoff between displacement and strain noise (or measurement noise) and spatial resolution for a wide variety of DIC codes by a combination of the images presented here and a performance factor called Metrological Efficiency Indicator (MEI). Results The performance of the 2D codes generally followed the expected theoretical performance, particularly in the measurement of the displacement. The comparison did however show that even with fairly uniform displacement performance, the calculation of the strain spatial resolution varied widely. Conclusions This work provides a useful framework for understanding the tradeoff and analyzing the performance of the DIC software using the provided images. It details some of the unique errors associated with the analysis of these images, such as the Pattern Induced Bias (PIB) and imprecision introduced through the strain calculation method. Future authors claiming improvements in 2D accuracy are encouraged to use these images for an unambiguous comparison.

18. General Consistency of Strong Discontinuity Kinematics in Embedded Finite Element Method (E-FEM) Formulations.

Author

Ortega Laborin A, Roubin E, Malecot Y, and Daudeville L

Abstract

This paper performs an in-depth study of the theoretical basis behind the strong discontinuity methods to improve local fracture simulations using the Embedded Finite Element Method (E-FEM). The process starts from a review of the elemental enhancement functions found in current E-FEM literature, providing the reader a solid context of E-FEM fundamentals. A set of theoretical pathologies is then discussed, which prevent current frameworks from attaining full kinematic consistency and introduce unintended mesh dependencies. Based on this analysis, a new proposal of strong discontinuity enhancement functions is presented considering generalised fracture kinematics in a full tridimensional setting and a more robust definition of internal auxiliary functions. Element-level simulations are performed to compare the outputs within a group of selected E-FEM approaches, including the novel proposal. Simulations show that the new element formulation grants a wider level of basic kinematic coherence between the local fracture outputs and element kinematics, demonstrating an increase in robustness that might drive the usefulness of E-FEM techniques for fracture simulations to a higher level.

Published
2021
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19. A peek into the origin of creep in sand.

Author

Andò E, Dijkstra J, Roubin E, Dano C, and Boller E

Abstract

This paper presents the results of an experimental study of the particle scale mechanisms that underpin creep, on-going deformations under constant external load, in dry non-cemented sand under 1D oedometric compression loading at 2500 kPa. Traditional observations on the boundary of the sample are complemented with simultaneous measurements of the 3D kinematics of both the entire grain assembly and details of grain-scale mechanisms using synchrotron based X-ray tomography at two different spatial resolutions. Both the continuum response and the local grain scale response are captured using two spatial resolutions, i.e.  6.5 μ m and 0.65 μ m respectively. The results, for the first time, illustrate that small displacements measured at the boundary can be the result of rather pronounced fracturing at the individual grain scale., Competing Interests: Compliance with ethical standardsThe authors declare no conflict of interest.

Published
2019
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