@article{svnbuses2024,

title = {A node-based uniform strain virtual element method for elastoplastic solids},

author = {R. Silva-Valenzuela and A. Ortiz-Bernardin and E. Artioli},

url = {https://camlab.cl/wp-content/uploads/2024/12/nvem_elastoplastic_rev1.pdf},

doi = {10.1007/s00466-024-02585-y},

year  = {2024},

date = {2024-12-20},

urldate = {2024-12-20},

journal = {Computational Mechanics},

abstract = {A recently proposed node-based uniform strain virtual element method (NVEM) is here extended to small strain elastoplastic solids. In the proposed method, the strain is averaged at the nodes from the strain of surrounding linearly precise virtual elements using a generalization to virtual elements of the node-based uniform strain approach for finite elements. The averaged strain is then used to sample the weak form at the nodes of the mesh leading to a method in which all the field variables, including state and history-dependent variables, are related to the nodes and thus they are tracked only at these locations during the nonlinear computations. Through various elastoplastic benchmark problems, we demonstrate that the NVEM is locking-free while enabling linearly precise virtual elements to solve elastoplastic solids with accuracy.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{yfe2024,

title = {Finite element graft stress for anteromedial portal, transtibial, and hybrid transtibial femoral drillings under anterior translation and medial rotation: an exploratory study},

author = {R. Yañez and R. Silvestre and M. Roby and A. Neira and C. Azar and S. Madera and A. Ortiz-Bernardin and F. P. Carpes and C. De la Fuente},

url = {https://camlab.cl/wp-content/uploads/2024/06/FE_graft_stress_for_anteromedial_portal.pdf

},

doi = {10.1038/s41598-024-61061-y},

year  = {2024},

date = {2024-05-24},

urldate = {2024-05-24},

journal = {Scientific Reports},

volume = {14},

pages = {11922},

abstract = {Stress concentration on the Anterior Cruciate Ligament Reconstruction (ACLr) for femoral drillings is crucial to understanding failures. Therefore, we described the graft stress for transtibial (TT), the anteromedial portal (AM), and hybrid transtibial (HTT) techniques during the anterior tibial translation and medial knee rotation in a finite element model. A healthy participant with a non-medical record of Anterior Cruciate Ligament rupture with regular sports practice underwent finite element analysis. We modeled TT, HTT, AM drillings, and the ACLr as hyperelastic isotropic material. The maximum Von Mises principal stresses and distributions were obtained from anterior tibial translation and medial rotation. During the anterior tibia translation, the HTT, TT, and AM drilling were 31.5 MPa, 34.6 Mpa, and 35.0 MPa, respectively. During the medial knee rotation, the AM, TT, and HTT drilling were 17.3 MPa, 20.3 Mpa, and 21.6 MPa, respectively. The stress was concentrated at the lateral aspect of ACLr,near the femoral tunnel for all techniques independent of the knee movement. Meanwhile, the AM tunnel concentrates the stress at the medial aspect of the ACLr body under medial rotation. The HTT better constrains the anterior tibia translation than AM and TT drillings, while AM does for medial knee rotation.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{obnbus2023,

title = {A node-based uniform strain virtual element method for compressible and nearly incompressible elasticity},

author = {A. Ortiz-Bernardin and R. Silva-Valenzuela and S. Salinas-Fernández and N. Hitschfeld-Kahler and S. Luza and B. Rebolledo},

url = {https://camlab.cl/wp-content/uploads/2024/06/node_based_vem_arxiv_r4.pdf},

doi = {10.1002/nme.7189},

year  = {2023},

date = {2023-04-30},

urldate = {2023-04-30},

journal = {International Journal for Numerical Methods in Engineering},

volume = {124},

number = {8},

pages = {1818-1855},

abstract = {We propose a combined nodal integration and virtual element method for compressible and nearly incompressible elasticity, wherein the strain is averaged at the nodes from the strain of surrounding virtual elements. For the strain averaging procedure, a nodal averaging operator is constructed using a generalization to virtual elements of the node-based uniform strain approach for finite elements. We refer to the proposed technique as the node-based uniform strain virtual element method (NVEM). No additional degrees of freedom are introduced in this approach, thus resulting in a displacement-based formulation. A salient feature of the NVEM is that the stresses and strains become nodal variables just like displacements, which can be exploited in nonlinear simulations. Through several benchmark problems in compressible and nearly incompressible elasticity as well as in elastodynamics, we demonstrate that the NVEM is accurate, optimally convergent and devoid of volumetric locking.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{sfpol2022,

title = {POLYLLA: polygonal meshing algorithm based on terminal-edge regions},

author = {S. Salinas-Fernández and N. Hitschfeld-Kahler and A. Ortiz-Bernardin and Hang Si},

url = {https://camlab.cl/wp-content/uploads/2024/06/2201.11925v2.pdf},

doi = {10.1007/s00366-022-01643-4},

year  = {2022},

date = {2022-05-03},

urldate = {2022-05-03},

journal = {Engineering with Computers},

volume = {38},

number = {5},

pages = {4545-4567},

abstract = {This paper presents an algorithm to generate a new kind of polygonal mesh obtained from triangulations. Each polygon is built from a terminal-edge region surrounded by edges that are not the longest-edge of any of the two triangles that share them. The algorithm is termed Polylla and is divided into three phases. The first phase consists of labeling each edge of the input triangulation according to its size; the second phase builds polygons (simple or not) from terminal-edges regions using the label system; and the third phase transforms each non simple polygon into simple ones. The final mesh contains polygons with convex and non convex shape. Since Voronoi-based meshes are currently the most used polygonal meshes, we compare some geometric properties of our meshes against constrained Voronoi meshes. Several experiments were run to compare the shape and size of polygons, the number of final mesh points and polygons. For the same input, Polylla meshes contain less polygons than Voronoi meshes and the algorithm is simpler and faster than the algorithm to generate constrained Voronoi meshes. Finally, we have validated Polylla meshes by solving the Laplace equation on an L-shaped domain using the virtual element method (VEM). We show that the numerical performance of the VEM using Polylla meshes and Voronoi meshes is similar.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{bmonncm2020,

title = {A novel nonlinear constitutive model for rock: numerical assessment and benchmarking},

author = {R. Bustamante and S. Montero and A. Ortiz-Bernardin},

url = {https://camlab.cl/wp-content/uploads/2024/06/nonlinear_constitutive_model_for_rock.pdf},

doi = {10.1016/j.apples.2020.100012},

year  = {2020},

date = {2020-09-14},

urldate = {2020-09-14},

journal = {Applications in Engineering Science},

volume = {3},

pages = {100012},

abstract = {In this article, we assess and benchmark a novel nonlinear constitutive relation for modeling the behavior of rock, in which the linearized strain tensor is a function of the Cauchy stress tensor. In stark contrast with the linearized theory of elasticity, the main feature of this novel nonlinear constitutive model is that a different behavior is obtained in compression than in tension, which is consisting with the experimental evidence. Four problems are solved using the finite element method: the compression of a cylinder, the biaxial compression of a slab with a circular hole and with an elliptic hole, and the shear of a slab with an elliptic hole. The results are compared with the predictions of the linearized theory of elasticity. In this comparison, it is found that the maximum stresses and their locations are significantly affected by the choice of the constitutive equation.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}