47 citations · 79 across the 24 of their papers we have counts for
30 papers
Minimization of energy functionals via FEM: implementation of hp-FEM
Miroslav Frost, Alexej Moskovka, Jan Valdman
Many problems in science and engineering can be rigorously recast into minimizing a suitable energy functional. We have been developing efficient and flexible solution strategies t…
Surface penalization of self-interpenetration in linear and nonlinear elasticity
Stefan Krömer, Jan Valdman
We analyze a term penalizing surface self-penetration, as a soft constraint for models of hyperelastic materials to approximate the Ciarlet-Nečas condition (almost everywhere globa…
Elastoplastic deformations of layered structures
Daria Drozdenko, Michal Knapek, Martin Kružík +3
We formulate a large-strain model of single-slip crystal elastoplasticity in the framework of energetic solutions. Numerical performance of the model is compared with lab experimen…
MATLAB implementation of hp finite elements on rectangles
Alexej Moskovka, Jan Valdman
A simple MATLAB implementation of hierarchical shape functions on 2D rectangles is explained and available for download. Global shape functions are ordered for a given polynomial d…
On the application of the SCD semismooth* Newton method to variational inequalities of the second kind
Helmut Gfrerer, Jiri V. Outrata, Jan Valdman
The paper starts with a description of the SCD (subspace containing derivative) mappings and the SCD semismooth* Newton method for the solution of general inclusions. This method i…
Linearization and Computation for Large-Strain Viscoelasticity
Patrick Dondl, Martin Jesenko, Martin Kružík +1
Time-discrete numerical minimization schemes for simple viscoelastic materials in the large strain Kelvin-Voigt rheology are not well-posed due to non-quasiconvexity of the dissipa…
Fast MATLAB evaluation of nonlinear energies using FEM in 2D and 3D: nodal elements
Alexej Moskovka, Jan Valdman
Nonlinear energy functionals appearing in the calculus of variations can be discretized by the finite element (FE) method and formulated as a sum of energy contributions from local…
On the solution of contact problems with Tresca friction by the semismooth* Newton method
Helmut Gfrerer, Jiri V. Outrata, Jan Valdman
An equilibrium of a linear elastic body subject to loading and satisfying the friction and contact conditions can be described by a variational inequality of the second kind and th…
Minimization of p-Laplacian via the Finite Element Method in MATLAB
Ctirad Matonoha, Alexej Moskovka, Jan Valdman
Minimization of energy functionals is based on a discretization by the finite element method and optimization by the trust-region method. A key tool is a local evaluation of the ap…
On the application of the semismooth* Newton method to variational inequalities of the second kind
Helmut Gfrerer, Jiri V. Outrata, Jan Valdman
The paper starts with a concise description of the recently developed semismooth* Newton method for the solution of general inclusions. This method is then applied to a class of va…
On computation of optimal strategies in oligopolistic markets respecting the cost of change
Jiří V. Outrata, Jan Valdman
The paper deals with a class of parametrized equilibrium problems, where the objectives of the players do possess nonsmooth terms. The respective Nash equilibria can be characteriz…
MATLAB Implementation of Element-based Solvers
Leszek Marcinkowski, Jan Valdman
Rahman and Valdman (2013) introduced a vectorized way to assemble finite element stiffness and mass matrices in MATLAB. Local element matrices are computed all at once by array ope…
Poincare-Friedrichs Type Constants for Operators Involving grad, curl, and div: Theory and Numerical Experiments
Dirk Pauly, Jan Valdman
We give some theoretical as well as computational results on Laplace and Maxwell constants. Besides the classical de Rham complex we investigate the complex of elasticity and the c…
MATLAB Implementation of C1 finite elements: Bogner-Fox-Schmit rectangle
Jan Valdman
Rahman and Valdman (2013) introduced a new vectorized way to assemble finite element matrices. We utilize underlying vectorization concepts and extend MATLAB codes to implementatio…
Numerical approximation of von Kármán viscoelastic plates
Manuel Friedrich, Martin Kružík, Jan Valdman
We consider metric gradient flows and their discretizations in time and space. We prove an abstract convergence result for time-space discretizations and identify their limits as c…
SpinDoctor: a Matlab toolbox for diffusion MRI simulation
Jing-Rebecca Li, Van-Dang Nguyen, Try Nguyen Tran +7
The complex transverse water proton magnetization subject to diffusion-encoding magnetic field gradient pulses in a heterogeneous medium can be modeled by the multiple compartment…
Global injectivity in second-gradient Nonlinear Elasticity and its approximation with penalty terms
Stefan Krömer, Jan Valdman
We present a new penalty term approximating the Ciarlet-Nečas condition (global invertibility of deformations) as a soft constraint for hyperelastic materials. For non-simple mater…
Interfacial polyconvex energy-enhanced evolutionary model for shape memory alloys
Miroslav Frost, Martin Kružík, Jan Valdman
A sharp-interface model describing static equilibrium configurations of shape mory alloys by means of interfacial polyconvex energy density introduced by Šilhavý in 2010 and extend…
Efficient and flexible MATLAB implementation of 2D and 3D elastoplastic problems
Martin Čermák, Stanislav Sysala, Jan Valdman
We propose an effective and flexible way to implement 2D and 3D elastoplastic problems in MATLAB using fully vectorized codes. Our technique is applied to a broad class of the prob…
Verifications of primal energy identities for variational problems with obstacles
Sergey Repin, Jan Valdman
We discuss error identities for two classes of free boundary problems generated by obstacles. The identities suggest true forms of the respective error measures which consist of tw…
Error identities for variational problems with obstacles
Sergey Repin, Jan Valdman
The paper is concerned with a class of nonlinear free boundary problems, which are usually solved by variational methods based on primal (or primal-dual) variational settings. We d…
Computational modeling of magnetic hysteresis with thermal effects
Martin Kružík, Jan Valdman
We study computational behavior of a mesoscopic model describing temperature/external magnetic field-driven evolution of magnetization. Due to nonconvex anisotropy energy describin…
A FEM approximation of a two-phase obstacle problem and its a posteriori error estimate
Farid Bozorgnia, Jan Valdman
This paper is concerned with the two--phase obstacle problem, a type of a variational free boundary problem. We recall the basic estimates of Repin and Valdman (2015) and verify th…
Stress-driven solution to rate-independent elasto-plasticity with damage at small strains and its computer implementation
Tomáš Roubíček, Jan Valdman
The quasistatic rate-independent damage combined with linearized plasticity with hardening at small strains is investigated. The fractional-step time discretisation is devised with…