@inproceedings{Heuer,
  author    = {Heuer, Andreas},
  title     = {THREE-DIMENSIONAL MODELING OF CONCRETE WITH DAMAGE AND PLASTICITY},
  editor    = {G{\"u}rlebeck, Klaus and K{\"o}nke, Carsten},
  organization    = {Bauhaus-Universit{\"a}t Weimar},
  doi       = {10.25643/bauhaus-universitaet.2967},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20170327-29671},
  pages     = {15},
  abstract  = {The concrete is modeled as a material with damage and plasticity, whereat the viscoplastic and the viscoelastic behaviour depends on the rate of the total strains. Due to the damage behaviour the compliance tensor develops different properties in tension and compression. There have been tested various yield surfaces and flow rules, damage rules respectively to their usability in a concrete model. One three-dimensional yield surface was developed from a failure surface based on the Willam--Warnke five-parameter model by the author. Only one general uni-axial stress-strain-relation is used for the numeric control of the yield surface. From that curve all necessary parameters for different strengths of concrete and different strain rates can be derived by affine transformations. For the flow rule in the compression zone a non associated inelastic potential is used, in the tension zone a Rankine potential. Conditional on the time-dependent formulation, the symmetry of the system equations is maintained in spite of the usage of non-associated potentials for the derivation of the inelastic strains. In case of quasi statical computations a simple viscoplastic law is used that is rested on an approach to Perzyna. The principle of equality of dissipation power in the uni-axial and the three-axial state of stress is used. It is modified by a factor that depends on the actual stress ratio and in comparison with the Kupfer experiments it implicates strains that are more realistic. The implementation of the concrete model is conducted in a mixed hybrid finite element. Examples in the structural level are introduced for verification of the concrete model.},
  subject      = {Architektur <Informatik>},
  language  = {en}
}
@inproceedings{Heinrich,
  author    = {Heinrich, Timo},
  title     = {KENNZEICHNUNGSBASIERTER ZUGRIFF VON PROZESSMODELLEN AUF OBJEKTBEST{\"A}NDE DES BAUWESENS},
  editor    = {G{\"u}rlebeck, Klaus and K{\"o}nke, Carsten},
  organization    = {Bauhaus-Universit{\"a}t Weimar},
  doi       = {10.25643/bauhaus-universitaet.2966},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20170327-29669},
  pages     = {13},
  abstract  = {F{\"u}r eine beherrschbare Koordination und Durchf{\"u}hrung von Planungsaufgaben in Bauprojekten wird der Planungsprozess zunehmend in formalisierten Modellen - Prozessmodellen - beschrieben. Die Produktmodellforschung ihrerseits widmet sich der Speicherung von Planungsdaten in Form von objektorientierten Modellen im Rechner. Hauptaugenmerk sind dabei die Wahrung der Konsistenz und die Modellierung von Abh{\"a}ngigkeiten innerhalb dieses Planungsmaterials. Der Bezug zu den Akteuren der Planung wird nicht direkt hergestellt. Ein formal beschriebener Planungsprozesses kann in der Praxis noch nicht derart realisiert werden, dass ein Zugriff auf Einzelobjekte des Planungsprozesses gew{\"a}hrleistet ist. Bestehende Planungsunterst{\"u}tzungs- und Workflowmanagement-Systeme abstrahieren und ordnen das Planungsmaterial nach wie vor auf Dateiebene. Der vorliegende Artikel beschreibt eine Methode f{\"u}r die geeignete Verbindung von formalisierten Prozessmodellen in der Bauplanung mit den Einzelobjekten, die in den modellorientierten Objektmengen kodiert sind. Dabei wird die Zugeh{\"o}rigkeit bestimmter Objekte zu Pl{\"a}nen und Dokumenten (zum Zwecke des Datenaustauschs) nicht l{\"a}nger durch die physische Zuordnung zu Dateien festgelegt. Es wird ein formales Beschreibungsmittel vorgestellt, welches die entsprechende Teilmengenbildung aus der Gesamtheit der Planungsobjekte erm{\"o}glicht. F{\"u}r die bisherigen Formen des Datenaustausches werden aus den Objektmodellen der Planung Teilmengen herausgel{\"o}st und physikalisch zwischen den Planern transportiert. Das neue Beschreibungsmittel hingegen erlaubt es, die Bildungsvorschrift f{\"u}r Objektteilmengen statt der Mengen selbst zwischen den Planern auszutauschen. Der Zugriff auf die konkreten Objekte findet dann direkt modellbasiert statt.},
  subject      = {Architektur <Informatik>},
  language  = {de}
}
@inproceedings{HapurneNistor,
  author    = {Hapurne, Tania Mariana and Nistor, S.},
  title     = {USING MODERN TECHNOLOGIES TO UPGRADE EDILITARY URBAN INFRASTRUCTURE},
  editor    = {G{\"u}rlebeck, Klaus and K{\"o}nke, Carsten},
  organization    = {Bauhaus-Universit{\"a}t Weimar},
  doi       = {10.25643/bauhaus-universitaet.2965},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20170327-29650},
  pages     = {6},
  abstract  = {Adopting the European laws concerning environmental protection will require sustained efforts of the authorities and communities from Romania; implementing modern solutions will become a fast and effective option for the improvement of the functioning systems, in order to prevent disasters. As a part of the urban infrastructure, the drainage networks of pluvial and residual waters are included in the plan of promoting the systems which protect the environmental quality, with the purpose of integrated and adaptive management. The paper presents a distributed control system for sewer network of Iasi town. Unsatisfactory technical state of the actual sewer system is exposed, focusing on objectives related to implementation of the control system. The proposed distributed control system of Iasi drainage network is based on the implementation of the hierarchic control theory for diagnose, sewer planning and management. There are proposed two control levels: coordinating and local execution. Configuration of the distributed control system, including data acquisition and conversion equipment, interface characteristics, local data bus, data communication network, station configuration are widely described. The project wish to be an useful instrument for the local authorities in the preventing and reducing the impact of future natural disasters over the urban areas by means of modern technologies.},
  subject      = {Architektur <Informatik>},
  language  = {en}
}
@inproceedings{HaefnerKesselKoenke,
  author    = {H{\"a}fner, Stefan and Kessel, Marco and K{\"o}nke, Carsten},
  title     = {MULTIPHASE B-SPLINE FINITE ELEMENTS OF VARIABLE ORDER IN THE MECHANICAL ANALYSIS OF HETEROGENEOUS SOLIDS},
  editor    = {G{\"u}rlebeck, Klaus and K{\"o}nke, Carsten},
  organization    = {Bauhaus-Universit{\"a}t Weimar},
  doi       = {10.25643/bauhaus-universitaet.2964},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20170327-29643},
  pages     = {37},
  abstract  = {Advanced finite elements are proposed for the mechanical analysis of heterogeneous materials. The approximation quality of these finite elements can be controlled by a variable order of B-spline shape functions. An element-based formulation is developed such that the finite element problem can iteratively be solved without storing a global stiffness matrix. This memory saving allows for an essential increase of problem size. The heterogeneous material is modelled by projection onto a uniform, orthogonal grid of elements. Conventional, strictly grid-based finite element models show severe oscillating defects in the stress solutions at material interfaces. This problem is cured by the extension to multiphase finite elements. This concept enables to define a heterogeneous material distribution within the finite element. This is possible by a variable number of integration points to each of which individual material properties can be assigned. Based on an interpolation of material properties at nodes and further smooth interpolation within the finite elements, a continuous material function is established. With both, continuous B-spline shape function and continuous material function, also the stress solution will be continuous in the domain. The inaccuracy implied by the continuous material field is by far less defective than the prior oscillating behaviour of stresses. One- and two-dimensional numerical examples are presented.},
  subject      = {Architektur <Informatik>},
  language  = {en}
}
@inproceedings{HaefnerKoenke,
  author    = {H{\"a}fner, Stefan and K{\"o}nke, Carsten},
  title     = {DAMAGE SIMULATION OF HETEROGENEOUS SOLIDS BY NONLOCAL FORMULATIONS ON ORTHOGONAL GRIDS},
  editor    = {G{\"u}rlebeck, Klaus and K{\"o}nke, Carsten},
  organization    = {Bauhaus-Universit{\"a}t Weimar},
  doi       = {10.25643/bauhaus-universitaet.2963},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20170327-29638},
  pages     = {15},
  abstract  = {The present paper is part of a comprehensive approach of grid-based modelling. This approach includes geometrical modelling by pixel or voxel models, advanced multiphase B-spline finite elements of variable order and fast iterative solver methods based on the multigrid method. So far, we have only presented these grid-based methods in connection with linear elastic analysis of heterogeneous materials. Damage simulation demands further considerations. The direct stress solution of standard bilinear finite elements is severly defective, especially along material interfaces. Besides achieving objective constitutive modelling, various nonlocal formulations are applied to improve the stress solution. Such a corrective data processing can either refer to input data in terms of Young's modulus or to the attained finite element stress solution, as well as to a combination of both. A damage-controlled sequentially linear analysis is applied in connection with an isotropic damage law. Essentially by a high resolution of the heterogeneous solid, local isotropic damage on the material subscale allows to simulate complex damage topologies such as cracks. Therefore anisotropic degradation of a material sample can be simulated. Based on an effectively secantial global stiffness the analysis is numerically stable. The iteration step size is controlled for an adequate simulation of the damage path. This requires many steps, but in the iterative solution process each new step starts with the solution of the prior step. Therefore this method is quite effective. The present paper provides an introduction of the proposed concept for a stable simulation of damage in heterogeneous solids.},
  subject      = {Architektur <Informatik>},
  language  = {en}
}
@inproceedings{HaefnerKoenke,
  author    = {H{\"a}fner, Stefan and K{\"o}nke, Carsten},
  title     = {MULTIGRID PRECONDITIONED CONJUGATE GRADIENT METHOD IN THE MECHANICAL ANALYSIS OF HETEROGENEOUS SOLIDS},
  editor    = {G{\"u}rlebeck, Klaus and K{\"o}nke, Carsten},
  organization    = {Bauhaus-Universit{\"a}t Weimar},
  doi       = {10.25643/bauhaus-universitaet.2962},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20170327-29626},
  pages     = {29},
  abstract  = {A fast solver method called the multigrid preconditioned conjugate gradient method is proposed for the mechanical analysis of heterogeneous materials on the mesoscale. Even small samples of a heterogeneous material such as concrete show a complex geometry of different phases. These materials can be modelled by projection onto a uniform, orthogonal grid of elements. As one major problem the possible resolution of the concrete specimen is generally restricted due to (a) computation times and even more critical (b) memory demand. Iterative solvers can be based on a local element-based formulation while orthogonal grids consist of geometrical identical elements. The element-based formulation is short and transparent, and therefore efficient in implementation. A variation of the material properties in elements or integration points is possible. The multigrid method is a fast iterative solver method, where ideally the computational effort only increases linear with problem size. This is an optimal property which is almost reached in the implementation presented here. In fact no other method is known which scales better than linear. Therefore the multigrid method gains in importance the larger the problem becomes. But for heterogeneous models with very large ratios of Young's moduli the multigrid method considerably slows down by a constant factor. Such large ratios occur in certain heterogeneous solids, as well as in the damage analysis of solids. As solution to this problem the multigrid preconditioned conjugate gradient method is proposed. A benchmark highlights the multigrid preconditioned conjugate gradient method as the method of choice for very large ratio's of Young's modulus. A proposed modified multigrid cycle shows good results, in the application as stand-alone solver or as preconditioner.},
  subject      = {Architektur <Informatik>},
  language  = {en}
}
@inproceedings{GurtovyTynchuk,
  author    = {Gurtovy, O. G. and Tynchuk, S.O.},
  title     = {RESEARCH OF DEFORMATION OF MULTILAYERED PLATES ON UNDEFORMABLE BASIS BY UNFLEXURAL SPECIFIED MODEL},
  editor    = {G{\"u}rlebeck, Klaus and K{\"o}nke, Carsten},
  organization    = {Bauhaus-Universit{\"a}t Weimar},
  doi       = {10.25643/bauhaus-universitaet.2961},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20170327-29613},
  pages     = {6},
  abstract  = {Stress-strain state (SSS) of multilayered plates on undeformable foundation is investigated. The settlement circuit of transverse loaded plate is formed by symmetrical attaching of a plate concerning a surface of contact to the foundation. The plate of the double thickness becomes bilateral symmetrically loaded concerning its median surface. It allows to model only unflexural deformation that reduces amount of unknown and the general order of differentiation of resolving system of the equations. The developed refined continual model takes into account deformations of transverse shear and transverse compression in high iterative approximation. Rigid contact between the foundation and a plate, and also shear without friction on a surface of contact of a plate with the foundation is considered. Calculations confirm efficiency of such approach, allowing to receive decisions which is qualitative and quantitatively close to three-dimensional solutions.},
  subject      = {Architektur <Informatik>},
  language  = {en}
}
@inproceedings{GruberValdman,
  author    = {Gruber, Peter and Valdman, J.},
  title     = {APPROXIMATE SOLUTION OF ELASTOPLASTIC PROBLEMS BASED ON THE MOREAU-YOSIDA THEOREM},
  editor    = {G{\"u}rlebeck, Klaus and K{\"o}nke, Carsten},
  organization    = {Bauhaus-Universit{\"a}t Weimar},
  doi       = {10.25643/bauhaus-universitaet.2960},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20170327-29602},
  pages     = {8},
  abstract  = {We propose a new approach to the numerical solution of quasi-static elastic-plastic problems based on the Moreau-Yosida theorem. After the time discretization, the problem is expressed as an energy minimization problem for unknown displacement and plastic strain fields. The dependency of the minimization functional on the displacement is smooth whereas the dependency on the plastic strain is non-smooth. Besides, there exists an explicit formula, how to calculate the plastic strain from a given displacement field. This allows us to reformulate the original problem as a minimization problem in the displacement only. Using the Moreau-Yosida theorem from the convex analysis, the minimization functional in the displacements turns out to be Frechet-differentiable, although the hidden dependency on the plastic strain is non-differentiable. The seconds derivative exists everywhere apart from the elastic-plastic interface dividing elastic and plastic zones of the continuum. This motivates to implement a Newton-like method, which converges super-linearly as can be observed in our numerical experiments.},
  subject      = {Architektur <Informatik>},
  language  = {en}
}
@inproceedings{Goettlicher,
  author    = {G{\"o}ttlicher, Manfred},
  title     = {HYBRID SOLID-LIQUID MODEL FOR GRANULAR MATERIAL},
  editor    = {G{\"u}rlebeck, Klaus and K{\"o}nke, Carsten},
  organization    = {Bauhaus-Universit{\"a}t Weimar},
  doi       = {10.25643/bauhaus-universitaet.2959},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20170327-29596},
  pages     = {20},
  abstract  = {Solid behavior as well as liquid behavior characterizes the flow of granular material in silos. The presented model is based on an appropriate interaction of a displacement field and a velocity field. The constitutive equations and the applied algorithm are developed from the exact solution for a standard case. The standard case evolves from a very tall vertical plane strain silo containing material that flows at a constant speed. No horizontal displacements and velocities take place. No changes regarding the field values arise in the vertical direction and in time. Tension is not allowed at any point. Coulomb friction represents the effects of the vertical walls. The interaction between the flowing material and the walls is covered by a forced boundary condition resulting in an additional matrix for the solid component as well as for the liquid component. The resulting integral equations are designed to be solved directly. Three coefficients describe the properties of the granular material. They govern elastic solid behavior in combination with viscous liquid behavior.},
  subject      = {Architektur <Informatik>},
  language  = {de}
}
@inproceedings{GoebelHildebrandWerner,
  author    = {G{\"o}bel, Michael and Hildebrand, J{\"o}rg and Werner, Frank},
  title     = {NUMERISCHES MODELL F{\"U}R DIE SIMULATION EINER LASERSTRAHLSCHWEIßUNG VON QUARZGLAS},
  editor    = {G{\"u}rlebeck, Klaus and K{\"o}nke, Carsten},
  organization    = {Bauhaus-Universit{\"a}t Weimar},
  doi       = {10.25643/bauhaus-universitaet.2958},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20170327-29589},
  pages     = {14},
  abstract  = {Ausgehend von den fundierten Erfahrungen, die f{\"u}r das Schweißen von verschiedensten Metallen vorliegen, wird an der Professur Stahlbau der Bauhaus-Universit{\"a}t Weimar ein neuartiges Verfahren zum CO2-Laserstrahlschweißen von Quarzglas numerisch untersucht. Dabei kommt die kommerzielle FE-Software SYSWELD® zum Einsatz. Die erforderlichen Versuche werden in Zusammenarbeit mit dem Institut f{\"u}r F{\"u}getechnik und Werkstoffpr{\"u}fung GmbH aus Jena realisiert. Die numerische Analyse wird eingesetzt, um geeignete Prozessparameter zu bestimmen und deren Auswirkungen auf die transienten thermischen und mechanischen Vorg{\"a}nge, die w{\"a}hrend des Schweißvorgangs ablaufen abzubilden. Um die aus der Simulation erhaltenen Aussagen zu {\"u}berpr{\"u}fen, ist es erforderlich, das Berechnungsmodell mittels Daten aus Versuchsschweißungen zu kalibrieren. Dabei sind die verwendeten Materialmodelle sowie die der Simulation zugrunde gelegten Materialkennwerte zu validieren. Es stehen verschiedene rheologische Berechnungsmodelle zur Auswahl, die die viskosen Materialeigenschaften des Glases abbilden. Dabei werden die drei mechanischen Grundelemente, die HOOKEsche Feder, der NEWTONsche D{\"a}mpfungszylinder und das ST.-VENANT-Element miteinander kombiniert. Die M{\"o}glichkeit, thermische und mechanische Vorg{\"a}nge innerhalb des Glases w{\"a}hrend des Schweißvorgangs und nach vollst{\"a}ndiger Abk{\"u}hlung, vorhersagen zu k{\"o}nnen, gestattet es den Schweißvorgang {\"u}ber eine Optimierung der Verfahrensparameter gezielt dahingehend zu beeinflussen, die Wirtschaftlichkeit des Schweißverfahrens zu verbessern, und ein zuverl{\"a}ssiges Schweißergebnis zu erhalten. Dabei k{\"o}nnen auch nur unter hohem experimentellen Aufwand durchf{\"u}hrbare Versuche simuliert werden, um eine Vorhersage zu treffen, ob es zweckm{\"a}ßig ist, den Versuch auch in der Praxis zu fahren. Dies f{\"u}hrt zu einer Reduzierung des experimentellen Aufwandes und damit zu einer Verk{\"u}rzung des Entwicklungszeitraumes f{\"u}r das angestrebte Verfahren.},
  subject      = {Architektur <Informatik>},
  language  = {de}
}