The Experts below are selected from a list of 163155 Experts worldwide ranked by ideXlab platform
Franzjosef Ulm - One of the best experts on this subject based on the ideXlab platform.
-
hybrid method for quantification of stress states in shotcrete tunnel shells combination of 3d in situ displacement measurements and thermochemoplastic Material Law
Computers & Structures, 2001Co-Authors: Christian Hellmich, Herbert A Mang, Franzjosef UlmAbstract:Abstract A hybrid method for quantification of the loading of shotcrete tunnel shells, combining thermochemomechanical Material modeling of shotcrete with 3D in situ displacement measurements in the framework of the non-linear finite element method, is presented. Histories of displacement fields, determined from in situ measurements by suitable interpolation functions, are prescribed on the outer boundary of a part of the tunnel, discretized in 2D or 3D. The main goal is the determination of fields of safety degrees, amounting to 0% for the unloaded shell and to 100% for the Material loaded up (locally) to the compressive strength. A comprehensive investigation of the significance of the individual Material characteristics of shotcrete as well as that of the third dimension in space on the structural behavior is performed. The Sieberg tunnel in Lower Austria, constituting a part of the high capacity railway line between Vienna and Salzburg, is used as the vehicle for this investigation. This tunnel was very recently completed.
U. Schomburg - One of the best experts on this subject based on the ideXlab platform.
-
a finite elastic viscoelastic elastoplastic Material Law with damage theoretical and numerical aspects
Computer Methods in Applied Mechanics and Engineering, 2003Co-Authors: R.c. Lin, U. SchomburgAbstract:Abstract The present work is concerned with the theoretical formulation and numerical implementation of a new isotropic finite elastic–viscoelastic–elastoplastic Material Law with Mullins’ damage for rubber-like Materials based on a set of dissipation inequalities published recently by the first author. A phenomenological model consisting of an elastic, an elastoplastic branch and N viscoelastic branches connected in parallel is exploited. The total free energy and the total stress are additively decomposed into three parts corresponding to the three types of branches. The damage effect is assumed to act on the three types of branches homogeneously and isotropically. According to the dissipation inequalities the evolution equations of the viscoelastic and elastoplastic branches are directly formulated in terms of the corotational rates of the internal elastic logarithmic strains. It is proved that in the present constitutive setting the internal elastic logarithmic strains are coaxial to the total and trial elastic logarithmic strains. The present theoretical and algorithmic formulations provide an alternative geometric representation of the same constitutive model outlined in [J. Mech. Phys. Solids 48 (2000) 323]. The numerical simulations show that the present Material Law gives predictions agreeing quite well with the experimental observations and numerical simulations issued in (loc. cit.).
-
A finite elastic–viscoelastic–elastoplastic Material Law with damage: theoretical and numerical aspects
Computer Methods in Applied Mechanics and Engineering, 2003Co-Authors: R.c. Lin, U. SchomburgAbstract:Abstract The present work is concerned with the theoretical formulation and numerical implementation of a new isotropic finite elastic–viscoelastic–elastoplastic Material Law with Mullins’ damage for rubber-like Materials based on a set of dissipation inequalities published recently by the first author. A phenomenological model consisting of an elastic, an elastoplastic branch and N viscoelastic branches connected in parallel is exploited. The total free energy and the total stress are additively decomposed into three parts corresponding to the three types of branches. The damage effect is assumed to act on the three types of branches homogeneously and isotropically. According to the dissipation inequalities the evolution equations of the viscoelastic and elastoplastic branches are directly formulated in terms of the corotational rates of the internal elastic logarithmic strains. It is proved that in the present constitutive setting the internal elastic logarithmic strains are coaxial to the total and trial elastic logarithmic strains. The present theoretical and algorithmic formulations provide an alternative geometric representation of the same constitutive model outlined in [J. Mech. Phys. Solids 48 (2000) 323]. The numerical simulations show that the present Material Law gives predictions agreeing quite well with the experimental observations and numerical simulations issued in (loc. cit.).
Werne Wagne - One of the best experts on this subject based on the ideXlab platform.
-
a piezoelectric solid shell element based on a mixed variational formulation for geometrically linear and nonlinear applications
Computers & Structures, 2008Co-Authors: Sve Klinkel, Werne WagneAbstract:The paper is focused on a piezoelectric solid shell finite element formulation. A geometrically nonlinear theory allows large deformations and includes stability problems. The formulation is based on a variational principle of the Hu-Washizu type including six independent fields: displacements, electric potential, strains, electric field, mechanical stresses and dielectric displacements. The element has eight nodes with displacements and the electric potential as nodal degrees of freedom. A bilinear distribution through the thickness of the electric field is assumed to obtain correct results in bending dominated situations. The presented element is able to model arbitrary curved shells and incorporates a 3D-Material Law. Numerical examples demonstrate the ability of the proposed model to analyze piezoelectric devices.
Christian Hellmich - One of the best experts on this subject based on the ideXlab platform.
-
hybrid method for quantification of stress states in shotcrete tunnel shells combination of 3d in situ displacement measurements and thermochemoplastic Material Law
Computers & Structures, 2001Co-Authors: Christian Hellmich, Herbert A Mang, Franzjosef UlmAbstract:Abstract A hybrid method for quantification of the loading of shotcrete tunnel shells, combining thermochemomechanical Material modeling of shotcrete with 3D in situ displacement measurements in the framework of the non-linear finite element method, is presented. Histories of displacement fields, determined from in situ measurements by suitable interpolation functions, are prescribed on the outer boundary of a part of the tunnel, discretized in 2D or 3D. The main goal is the determination of fields of safety degrees, amounting to 0% for the unloaded shell and to 100% for the Material loaded up (locally) to the compressive strength. A comprehensive investigation of the significance of the individual Material characteristics of shotcrete as well as that of the third dimension in space on the structural behavior is performed. The Sieberg tunnel in Lower Austria, constituting a part of the high capacity railway line between Vienna and Salzburg, is used as the vehicle for this investigation. This tunnel was very recently completed.
R.c. Lin - One of the best experts on this subject based on the ideXlab platform.
-
a finite elastic viscoelastic elastoplastic Material Law with damage theoretical and numerical aspects
Computer Methods in Applied Mechanics and Engineering, 2003Co-Authors: R.c. Lin, U. SchomburgAbstract:Abstract The present work is concerned with the theoretical formulation and numerical implementation of a new isotropic finite elastic–viscoelastic–elastoplastic Material Law with Mullins’ damage for rubber-like Materials based on a set of dissipation inequalities published recently by the first author. A phenomenological model consisting of an elastic, an elastoplastic branch and N viscoelastic branches connected in parallel is exploited. The total free energy and the total stress are additively decomposed into three parts corresponding to the three types of branches. The damage effect is assumed to act on the three types of branches homogeneously and isotropically. According to the dissipation inequalities the evolution equations of the viscoelastic and elastoplastic branches are directly formulated in terms of the corotational rates of the internal elastic logarithmic strains. It is proved that in the present constitutive setting the internal elastic logarithmic strains are coaxial to the total and trial elastic logarithmic strains. The present theoretical and algorithmic formulations provide an alternative geometric representation of the same constitutive model outlined in [J. Mech. Phys. Solids 48 (2000) 323]. The numerical simulations show that the present Material Law gives predictions agreeing quite well with the experimental observations and numerical simulations issued in (loc. cit.).
-
A finite elastic–viscoelastic–elastoplastic Material Law with damage: theoretical and numerical aspects
Computer Methods in Applied Mechanics and Engineering, 2003Co-Authors: R.c. Lin, U. SchomburgAbstract:Abstract The present work is concerned with the theoretical formulation and numerical implementation of a new isotropic finite elastic–viscoelastic–elastoplastic Material Law with Mullins’ damage for rubber-like Materials based on a set of dissipation inequalities published recently by the first author. A phenomenological model consisting of an elastic, an elastoplastic branch and N viscoelastic branches connected in parallel is exploited. The total free energy and the total stress are additively decomposed into three parts corresponding to the three types of branches. The damage effect is assumed to act on the three types of branches homogeneously and isotropically. According to the dissipation inequalities the evolution equations of the viscoelastic and elastoplastic branches are directly formulated in terms of the corotational rates of the internal elastic logarithmic strains. It is proved that in the present constitutive setting the internal elastic logarithmic strains are coaxial to the total and trial elastic logarithmic strains. The present theoretical and algorithmic formulations provide an alternative geometric representation of the same constitutive model outlined in [J. Mech. Phys. Solids 48 (2000) 323]. The numerical simulations show that the present Material Law gives predictions agreeing quite well with the experimental observations and numerical simulations issued in (loc. cit.).