Showing papers by "Antonio Rodríguez-Ferran published in 2020"
TL;DR: A new adaptive refinement strategy for phase-field models of brittle fracture is proposed, which provides a computationally efficient solution to the high demand in spatial resolution of phase- field models.
Abstract: A new adaptive refinement strategy for phase-field models of brittle fracture is proposed. The approach provides a computationally efficient solution to the high demand in spatial resolution of phase-field models. The strategy is based on considering two types of elements: h-refined elements along cracks, where more accuracy is needed to capture the solution, and standard elements in the rest of the domain. Continuity between adjacent elements of different type is imposed in weak form by means of Nitsche’s method. The weakly imposition of continuity leads to a very local refinement in a simple way, for any degree of approximation and both in 2D and 3D. The performance of the strategy is assessed for several scenarios in the quasi-static regime, including coalescence and branching of cracks in 2D and a twisting crack in 3D.
32 citations
TL;DR: Muixi et al. as mentioned in this paper proposed a hybridizable discontinuous Galerkin phase-field model for brittle fracture with adaptive refinement, which has been published in final form at DOI: 10.1002/nme.6260.
Abstract: This is the peer reviewed version of the following article: Muixi, A.; Rodriguez-Ferran, A.; Fernandez, S. A hybridizable discontinuous Galerkin phase-field model for brittle fracture with adaptive refinement. "International journal for numerical methods in engineering", 30 Marc 2020, vol. 121, num. 6, p. 1147-1169, which has been published in final form at DOI: 10.1002/nme.6260. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.
24 citations
TL;DR: The results suggest that reduction of junctional stiffness rather than cytoplasmic stiffness has a more pronounced effect on shortening closure times, and that intercalation rate has a minor effect on the stored energy, but contributes significantly to shortening the healing duration, mostly in the later stages.
Abstract: Wound healing is characterized by the re-epitheliation of a tissue through the activation of contractile forces concentrated mainly at the wound edge. While the formation of an actin purse string has been identified as one of the main mechanisms, far less is known about the effects of the viscoelastic properties of the surrounding cells, and the different contribution of the junctional and cytoplasmic contractilities. In this paper, we simulate the wound healing process, resorting to a hybrid vertex model that includes cell boundary and cytoplasmic contractilities explicitly, together with a differentiated viscoelastic rheology based on an adaptive rest-length. From experimental measurements of the recoil and closure phases of wounds in the Drosophila wing disc epithelium, we fit tissue viscoelastic properties. We then analyse in terms of closure rate and energy requirements the contributions of junctional and cytoplasmic contractilities. Our results suggest that reduction of junctional stiffness rather than cytoplasmic stiffness has a more pronounced effect on shortening closure times, and that intercalation rate has a minor effect on the stored energy, but contributes significantly to shortening the healing duration, mostly in the later stages.
8 citations
TL;DR: In this paper, a quasi-two-dimensional set-up with novel features including: a lifting gate activated by a parallelogram mechanism for material release, a reversible pneumatic circuit to impose fluidised and vacuum conditions to the initial granular column, a set of load cells to monitor the basal load distribution during flow propagation, a 3D laser line profile sensor to scan the free surface morphology of the samples at rest, and a high-speed video recording set to capture nearwall flow visualisations and relevant kinematic measures by particle image velocimetry.
7 citations
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TL;DR: In this paper, the phase-field equations are solved only in small subdomains around crack tips to determine propagation, while an XFEM discretization is used in the rest of the domain to represent sharp cracks, enabling to use a coarser discretisation and therefore reducing the computational cost.
Abstract: This paper presents an adaptive strategy for phase-field simulations with transition to fracture. The phase-field equations are solved only in small subdomains around crack tips to determine propagation, while an XFEM discretization is used in the rest of the domain to represent sharp cracks, enabling to use a coarser discretization and therefore reducing the computational cost. Crack-tip subdomains move as cracks propagate in a fully automatic process. The same computational mesh is used during all the simulation, with an $h$-refined approximation in the elements in the crack-tip subdomains. Continuity of the displacement between the refined subdomains and the XFEM region is imposed in weak form via Nitsche's method. The robustness of the strategy is shown for some numerical examples in 2D and 3D, including branching and coalescence tests.
3 citations
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TL;DR: In this paper, the authors studied the mechanical aspects that make a pilar (the simplest structure in the castells) to stand, and proposed three different but complementary approaches for the running stage of a castell: the $N$-link pendulum as a first dynamical model, the response of the castellers as a control problem and a static analysis to capture the feasibility of a given configuration.
Abstract: Human towers or castells are human structures played in festivals mainly in Catalonia. These unique cultural and traditional displays have become very popular in the last years, but they date from the XVIII century. On 2010 they became part of the Unesco Representative List of the Intangible Cultural Heritage of Humanity.
Safety is very important in the performance of castells. To this end, it is crucial to understand the mechanisms that allow a castell to be built and, more importantly, the factors that may cause its collapse. This work is focused on the mechanical aspects that make a pilar (the simplest structure in the castells) to stand. We suggest three different but complementary approaches for the running stage of a pilar (stage where it has been built and has not yet collapsed): the $N$-link pendulum as a first dynamical model, the response of the castellers as a control problem, and a static analysis to capture the feasibility of a given configuration. We include some preliminary simulations to better understand the previous approaches, which seem to match with qualitative perceptions that castellers have of a castell. Possible future developments are also discussed. To our knowledge, this work represents the first one to study the castells from a mechanical point of view.
TL;DR: It is suggested that reduction of junctional stiffness rather than cytoplasmatic stiffness has a more pronounced effect on shortening closure times, and that intercalation rate has a minor effect on the stored energy, but contributes significantly to shortening the healing process, mostly in the later stages.
Abstract: Wound healing is characterised by the re-epitheliation of a tissue through the activation of contractile forces concentrated mainly at the wound edge. While the formation of an actin purse string has been identified as one of the main mechanisms, far less is known about the effects of the viscoelastic properties of the surrounding cells, and the different contribution of the junctional and cytoplasmic contractilities.
In this paper we simulate the wound healing process, resorting to a hybrid vertex model that includes cell boundary and cytoplasmatic contractilities explicitly, together with a differentiated viscoelastic rheology based on an adaptive rest-length. From experimental measurements of the recoil and closure phases of wounds in the Drosophila wing disc epithelium, we fit tissue viscoelastic properties. We then analyse in terms of closure rate and energy requirements the contributions of junctional and cytoplasmatic contractilities.
Our results suggest that reduction of junctional stiffness rather than cytoplasmatic stiffness has a more pronounced effect on shortening closure times, and that intercalation rate has a minor effect on the stored energy, but contributes significantly to shortening the healing process, mostly in the later stages.