Shen, Yongxing
Total activity: 24

## Scientific and technological production Ordered by:  Date asc. Date desc. Title asc. Title desc. Researcher asc. Researcher desc.

1 to 24 of 24 results
• A locking-free and optimally convergent discontinuous-Galerkin-based extended finite element method for cracked nearly incompressible solids

Computer methods in applied mechanics and engineering
Vol. 273, p. 119-142
DOI: 10.1016/j.cma.2014.01.017
Date of publication: 2014-05-01
Journal article

The extended finite element method (XFEM) is an efficient way to include discontinuities, such as a crack, into a finite element mesh. The singularity at the crack tip restricts standard finite element methods to converge with a rate of at most 1/2 for the stresses, and I for the displacements, with respect to the mesh size. This is true for cracks in incompressible materials as well, when any of the standard techniques to sidestep locking is adopted. To attain an optimal convergence rate of 1 for stresses and of 2 for displacements with piecewise affine elements, it is necessary to enrich the finite element space with singular basis functions. The support of these singular functions is the entire plane, but to avoid decreasing the sparsity of the stiffness matrix too much, each of them is then generally localized to a neighborhood of the crack tip by multiplying by a cutoff function or a subset of a partition-of-unity basis. For nearly incompressible materials, however, the resulting basis functions no longer contain incompressible displacement fields, and hence they either lead to locking or suboptimal convergence rates. To overcome this problem, we introduce here an XFEM with optimal convergence rate and without the problem of locking for nearly incompressible materials, i.e., it possesses an error bound that does not diverge as Poisson's ratio approaches 0.5. The method is based on a primal, or one-field formulation of a discontinuous Galerkin method that we introduced earlier. This one-field formulation is obtained through the introduction of a lifting operator, but unlike most lifting operators which map inter-element discontinuities into elementwise polynomials, ours maps such discontinuities into spaces enriched with the singular behavior of the solution. This is the key idea for the method to be simultaneously locking-free and optimally convergent. (C) 2014 Elsevier B.V. All rights reserved.

• A variational inequality formulation to incorporate the fluid lag in fluid-driven fracture propagation

Shen, Yongxing
Computer methods in applied mechanics and engineering
Vol. 272, p. 17-33
DOI: 10.1016/j.cma.2014.01.006
Date of publication: 2014-04-15
Journal article

We have developed an efficient method to model the fluid lag in fluid-driven fracture propagation via a variational inequality formulation. The distinct feature of this method is that the configurations with and without a lag can be handled in a unified framework and no change of formulation is needed during the simulation at the time the fracturing liquid reaches the fracture tip. This is achieved by formulating the problem as solving for the non-negative pressure field in the fracture via a time-dependent (parabolic) variational inequality. Without introducing extra assumptions but merely based on mass conservation, this method is able to predict whether a fluid lag is going to remain or completely disappear as the fracturing progresses. (C) 2014 Elsevier B.V. All rights reserved.

• Phase-field modeling of fracture in linear thin shells

Amiri, Fatemeh; Millán, Daniel; Shen, Yongxing; Rabczuk, Timon; Arroyo Balaguer, Marino
Theoretical and applied fracture mechanics
Vol. 69, p. 102-109
DOI: 10.1016/j.tafmec.2013.12.002
Date of publication: 2014-02
Journal article

We present a phase-field model for fracture in Kirchoff-Love thin shells using the local maximum-entropy (LME) meshfree method. Since the crack is a natural outcome of the analysis it does not require an explicit representation and tracking, which is advantage over techniques as the extended finite element method that requires tracking of the crack paths. The geometric description of the shell is based on statistical learning techniques that allow dealing with general point set surfaces avoiding a global parametrization, which can be applied to tackle surfaces of complex geometry and topology. We show the flexibility and robustness of the present methodology for two examples: plate in tension and a set of open connected pipes.

• Mètodes numèrics en ciències aplicades i enginyeria

Sarrate Ramos, Jose; Diez Mejia, Pedro; Rodriguez Ferran, Antonio; Fernandez Mendez, Sonia; Arias Vicente, Irene; Arroyo Balaguer, Marino; Parés Mariné, Núria; Muñoz Romero, Jose Javier; Discacciati, Marco; Zlotnik, Sergio; de Villardi de Montlaur, Adeline; Poblet Puig, Jordi; Shen, Yongxing; Huerta Cerezuela, Antonio
Competitive project

• Numerical simulation of soil-water jet interaction with smoothed particle hydrodynamics

Guo, Zhiming; Shao, Jiaru; Shen, Yongxing; Liu, Moubin
International Conference on Particle-based Methods
p. 418-427
Presentation's date: 2013-09
Presentation of work at congresses

Smoothed particle hydrodynamics (SPH) is a meshfree, Lagrangian particle method, which has been applied to different areas in sciences and industrial applications. In this work, SPH is used to simulate the soil-water jet interaction and erosion. In the simulation, water is modelled as a viscous fluid with weak compressibility and the soil is assumed to be an elastic-perfectly plastic material. The stress states of soil in the plastic flow regime follow the Drucker-Prager failure criterion. Both the shear and tensile criterions are used for the yield of soil particles if the yield point is reached and the total stress of the particle is scaled. Instead of computing particle pressure from an equation of state, the spherical stress is computed by dividing total stress into spherical stress and deviatoric stress. The interaction of coupling interfaces is strengthened by a penalty function to avoid unphysical penetration between particles from different materials. The obtained numerical results have shown that SPH could be a valuable method for the simulation of complex soil water interaction.

• Numerical simulation of explosive fracturing with smoothed particle hydrodynamics

Guo, Zhiming; Shen, Yongxing; Liu, Moubin
International Conference on Computational Methods for Coupled Problems in Science and Engineering
p. p873-1-p873-12
Presentation's date: 2013-06-17
Presentation of work at congresses

• Using massively parallel processors to simulate crack propagation problems with the phase-field formulation

International Conference on Computational Modeling of Fracture and Failure of Materials and Structures
p. 199
Presentation's date: 2013-06-05
Presentation of work at congresses

• Efficient methods to take into account the fluid lag in hydraulic fracturing simulations through a variational inequality formulation

Shen, Yongxing
Annual Technical Conference of Society of Engineering Sciences
p. 1
Presentation's date: 2012-10
Presentation of work at congresses

• Efficient methods to take into account the fluid lag in hydraulic fracturing simulations through a variational inequality formulation

Shen, Yongxing
European Congress on Computational Methods in Applied Sciences and Engineering
p. 270
Presentation's date: 2012-09-12
Presentation of work at congresses

• Efficient methods to take into account the fluid lag in hydraulic fracturing simulations through a variational inequality formulation

Shen, Yongxing
International Congress of Theoretical and Applied Mechanics
p. 1
Presentation's date: 2012-08
Presentation of work at congresses

• Computer Metrods to predict three-dimensional hydraulic fracture networks

Shen, Yongxing; Arroyo Balaguer, Marino
Competitive project

• A family of discontinuous Galerkin mixed methods for nearly and perfectly incompressible elasticity

ESAIM. Mathematical modeling and numerical analysis. Modelisation mathématique
Vol. 46, num. 5, p. 1003-1028
DOI: 10.1051/m2an/2011046
Date of publication: 2012
Journal article

• A finite element approach to the simulation of hydraulic fractures with lag

Hunsweck, Michael J.; Shen, Yongxing; Lew, Adrian J.
International journal for numerical and analytical methods in geomechanics
DOI: 10.1002/nag.1131
Date of publication: 2012
Journal article

• Fractura de láminas finas debido a la interacción fluido-estructura

Arroyo Balaguer, Marino; Millan, Raul Daniel; Rabczuk, Timon; Amiri, Fatemeh; Ziaei Rad, Vahid; Shen, Yongxing
Competitive project

• Simulation of hydraulic fracturing: interaction between a cracked solid and the lubrication flow in the crack

Hunsweck, Michael J.; Shen, Yongxing; Lew, Andrew J.
International Conference on Computational Modeling of Fracture and Failure of Materials and Structures
p. 87
Presentation's date: 2011-06-08
Presentation of work at congresses

• A robust discontinuous-Galerkin-based extended finite element method for fracture problems with nearly incompressible elasticity

Shen, Yongxing; Lew, Andrew J.
International Conference on Computational Modeling of Fracture and Failure of Materials and Structures
p. 64
Presentation's date: 2011-06-08
Presentation of work at congresses

• An optimally convergent discontinuous Galerkin-based extended finite element method for fracture mechanics

International journal for numerical methods in engineering
Vol. 82, num. 6, p. 716-755
DOI: 10.1002/nme.2781
Date of publication: 2010
Journal article

• Stability and convergence proofs for a discontinuous-Galerkin-based extended finite element method for fracture mechanics

Computer methods in applied mechanics and engineering
Vol. 199, num. 37-40, p. 2360-2382
DOI: 10.1016/j.cma.2010.03.008
Date of publication: 2010
Journal article

• MÈTODES NUMÈRICS EN CIÈNCIES APLICADES I ENGINYERIA

Roca Navarro, Francisco Javier; Giorgiani, Giorgio; Zlotnik, Sergio; Fernandez Mendez, Sonia; Rodriguez Ferran, Antonio; Muñoz Romero, Jose Javier; Arias Vicente, Irene; de Villardi de Montlaur, Adeline; Sarrate Ramos, Jose; Diez Mejia, Pedro; Arroyo Balaguer, Marino; Sevilla Cardenas, Ruben; Parés Mariné, Núria; Casoni Rero, Eva; Ruiz Girones, Eloi; Modesto Galende, David; Millan, Raul Daniel; Abdollahi Hosnijeh, Amir; Steffens, Lindaura Maria; Discacciati, Marco; Shen, Yongxing; Rahimi Lenji, Mohammad; Tamayo Mas, Elena; Diaz Cereceda, Cristina; Prat Robles, David; Verdugo Rojano, Francesc; Zhang, Kuan; Estela Carbonell, M. Rosa; Peco Regales, Christian; Pérez Foguet, Agustí; Angeloski, Aleksandar; Gargallo Peiró, Abel; Huerta Cerezuela, Antonio
Competitive project

• Analytic perturbation solution to the capacitance system of a hyberboloidal tip and a rough surface

Shen, Yongxing; Barnett, David M.; Pinsky, Peter M.
Applied physics letters
Vol. 92, num. 13, p. 134105-
DOI: 10.1063/1.2906487
Date of publication: 2008
Journal article

The capacitance system of a hyperboloidal tip and a rough surface is usually encountered in analyzing electrostatic force microscopy images. In this letter, a perturbation approach has been applied to solve for the electric potential of this system, in which the rough surface is treated as perturbation from a flat one. For the first-variation solution, the boundary value problem is represented in the prolate-spheroidal coordinate system and solved in terms of a generalized Fourier series involving conical functions. Based on this solution, the tip-surface Coulombic interaction can be computed. Sample calculations have been applied to sinusoidal surface profiles

• Modeling electrostatic force microscopy for conductive and dielectric samples using the boundary element method

Shen, Yongxing; Barnett, David M.; Pinsky, Peter M.
Engineering analysis with boundary elements
Vol. 32, num. 8, p. 682-691
DOI: 10.1016/j.enganabound.2007.12.003
Date of publication: 2008
Journal article

• Simulating and interpreting Kelvin probe force microscopy images on dielectrics with boundary integral equations

Shen, Yongxing; Barnett, David M.; Pinsky, Peter M.
Review of scientific instruments
Vol. 79, num. 2, p. 023711-
DOI: 10.1063/1.2885679
Date of publication: 2008
Journal article

Kelvin probe force microscopy KPFM is designed for measuring the tip-sample contact potential differences by probing the sample surface, measuring the electrostatic interaction, and adjusting a feedback circuit. However, for the case of a dielectric insulating sample, the contact potential difference may be ill defined, and the KPFM probe may be sensing electrostatic interactions with a certain distribution of sample trapped charges or dipoles, leading to difficulty in interpreting the images.We have proposed a general framework based on boundary integral equations for simulating the KPFM image based on the knowledge about the sample charge distributions forward problem and a deconvolution algorithm solving for the trapped charges on the surface from an image inverse problem . The forward problem is a classical potential problem, which can be efficiently solved using the boundary element method. Nevertheless, the inverse problem is ill posed due to data incompleteness. For some special cases, we have developed deconvolution algorithms based on the forward problem solution. As an example, this algorithm is applied to process the KPFM image of a gadolinia-doped ceria thin film to solve for its surface charge density, which is a more relevant quantity for samples of this kind than the contact potential difference normally only defined for conductive samples values contained in the raw image.

• A resolution study for electrostatic force microscopy on bimetallic samples using the boundary element method

Shen, Yongxing; Lee, Minhwan; Lee, Wonyoung; Barnett, David M.; Pinsky, Peter M.; Prinz, Friedrich B.
Nanotechnology
Vol. 19, num. 3, p. 035710-
DOI: 10.1088/0957-4484/19/03/035710
Date of publication: 2007
Journal article

• An extended invariant line analysis for fcc/bcc precipitation systems

Qiu, Dong; Shen, Yongxing; Zhang, Wen-Zheng
Acta materialia
Vol. 54, num. 2, p. 339-347
DOI: 10.1016/j.actamat.2005.09.009
Date of publication: 2006
Journal article