RUB Research School RUB Comp-Eng RUB RD SME RUB AGES SFB 837 FOR 1498 ASCE - EMI SPP 1886 EURO-C 2018


Aktuelles

 

Videos zu Vorlesungen am Lehrstuhl erneut anschauen


Es ist nun möglich Videos zu folgenden Vorlesungen erneut am Lehrstuhl anzuschauen:

- FEM in Linear Structural Mechanics
- Baustatik I
- Baustatik III

Bitte vereinbaren Sie einen Termin im Sekretariat bei Frau Schützner (svenja.schuetzner@rub.de)

 


FORUM FOR YOUNG ENGINEERING PROFESSIONALS


In late 2017, seven PhD students of the SFB 837 have founded a German-wide forum for junior scientists in tunneling, namely the „Forum For Young Engineering Professionals“.
The forum supports young engineers in taking the step from studies to their further career and establishes contacts within the tunneling community. The Kick-off Meeting, which was attended by nearly 100 engineers from industry and research, took place on 6th December 2017 at STUVA, an international conference for tunnels and infrastructure. The next meeting in spring 2018 will be hosted by the SFB 837.

 


Image-based numerical prediction for effective thermal conductivity of heterogeneous materials: A quadtree based scaled boundary finite element metho
Dr. Yiqian He (Dalian University of Technology, China)

Dr. Yiqian He from the Dalian University of Technology, China, will hold a guest lecture in the framework of SFB 837 about 'Image-based numerical prediction for effective thermal conductivity of heterogeneous materials: A quadtree based scaled boundary finite element method'.

The evaluation of Effective Thermal Conductivity (ETC) for heterogeneous materials is of interest in many heat transfer applications. For example, the ETC is proved to be one of the most important parameters in packed beds, metal foams and sponges, functionally graded materials, granular materials and fibrous porous materials, etc.
In this talk, a new framework that centres about a quadtree based scaled boundary finite element method (SBFEM) is developed for the heat transfer analysis and the estimation of ETC. Two significant advantages of the proposed methods includes:

  1. The proposed method can be used to model the geometrical features directly based on images. Each generated quadtree or octree cell can be modelled as a scaled boundary polygonal element or a scaled boundary polyhedral element, respectively, which eliminates the hanging node issue encountered in the FEM and XFEM. Furthermore, as the element solutions for cells of the same pattern but different sizes are proportional, so the efficiency of this approach is high, because the limited cell patterns generated can be precomputed and quickly extracted when required.

  2. An inverse analysis is presented to numerically evaluate the ETC. The inclusions are considered to be randomly distributed. The temperatures values at some sample points in the heterogeneous material is calculated as the measured points, and then the ETC is identified in an equivalent material model by solving an inverse problems, in which the sensitivity is calculated and the Gauss-Newton method is used.



Numerical examples are provided to demonstrate the effectiveness of the proposed method, considering the distribution of circular or elliptical inclusions are random, and the influence of the size and shape of inclusions are investigated.

Am: 07.12.2017
Um: 16:30
Ort: ID 04 / 471

see PDF file for more information

 


Modelling the Third Kind Boundary Condition in Scaled Boundary Finite Element Method Based Numerical Analysis
Prof. Haitian Yang (Dalian University of Technology, China)

Prof. Haitian Yang form the Dalian University of Technology, China, will hold a guest lecture in the framework of SFB 837 about 'Modelling the Third Kind Boundary Condition in Scaled Boundary Finite Element Method Based Numerical Analysis'.

The third kind boundary condition usually gives relationships between functions and their derivatives along the boundary, and often appears in modelling interactions between two structures, for instance, the interaction between surrounding rock and tunnel, the interaction between buildings and foundation, and the interaction between tunnel segments and so on. In the modelling process, the impact of one structure on another is described by the third kind boundary condition.

Numerical algorithms to deal with the third kind boundary condition (TKBC) are presented under the framework of Scaled Boundary Finite Element Method (SBFEM) By smoothing the bilinear TKBC, a differentiable relationship is derived, and a gradient based numerical algorithm is proposed in the solution process. For viscoelastic TKBC, a recursive constitutive equation is derived, and a temporally-piecewised algorithm is developed. In addition, a proof that the appended stiffness matrix is block-circulant is presented when the TKBC are cyclic symmetric, resulting in a reduction of computational expense of SBFEM based numerical analysis. Numerical examples are given to verify proposed approaches, and satisfactory results are obtained.

Am: 07.12.2017
Um: 15:30
Ort: ID 04 / 471

see PDF file for more information

 


Workshop Multiscale Modeling and Simulation of Fracture


In the run-up to the Workshop "Multiscale Modeling and Simulation of Fracture" Prof. Michael Ortiz will give a guest lecture on "Multiscale Modeling And Simulation Of Fracture And Fragmentation – Application To Fused Silica Glass".

The Guest Lecture by Prof. Ortiz is followed by four presentations by Ph.D. and PostDoc researchers:

  • Coupled Two-Scale Simulation Of Multiphase Steel
    A. Gandhi and D. Balzani

  • Variational Interface Model In Solid And Hydraulic Fracturing Problems
    I. Khisamitov and G. Meschke

  • A Relaxation-Based Approach To Damage Modeling
    P. Junker and K. Hackl

  • Multiscale Modeling Of Transport And Deterioration In Porous Materials
    J.J. Timothy and G. Meschke



Am: 29.11.2017
Um: 13:53
Ort: IC 03 / 606

see PDF file for more information

 


Guest Lecture Prof. M. ORTIZ (California Institute of Technology, USA): Multiscale Modeling And Simulation Of Fracture And Fragmentation – Application To Fused Silica Glass
Prof. Michael Ortiz (California Institute of Technology, USA and Hausdorff Center for Mathematics, Germany)

Prof. Michael Ortiz from the California Institute of Technology, USA and Hausdorff Center for Mathematics, Germany will hold a guest lecture in the framework of SFB 837 about 'Multiscale Modeling And Simulation Of Fracture And Fragmentation – Application To Fused Silica Glass'.

The anomalous shear modulus behavior of fused silica glass has been a long-standing topic of investigation. Likewise, the anomalous pressure dependence of the strength of amorphous silica has also received considerable attention. In order to formulate a model of material behavior, we perform molecular dynamics (MD) calculations designed to data-mine information regarding the permanent deformation, both volumetric and in shear, of amorphous silica. Based on these observations, we formulate a critical-state constitutive model for fused silica and fit material parameters to the MD data. Remarkably, the MD data reveals that the limit yield surface is non-convex. The treatment of this non-convexity necessitates a fundamental extension of classical plasticity. We consider the implications of this extension and utilize tools from the Direct Methods in the Calculus of Variation to characterize explicitly the effective behavior at the macro-scale. The resulting effective model of plasticity, together with consideration of brittle fracture of fragmentation, provide the basis for the simulation of failure waves in glass rods impacting a rigid target. The calculations are carried out using the Optimal-Transportation Meshfree (OTM) method combined with the eigenerosion approach to fracture. This computational approach proves effective at predicting the experimentally observed failure wave speeds and complex fracture and fragmentation patterns, while simultaneously allowing for complex material behavior.

Am: 29.11.2017
Um: 13:30
Ort: IC 03 / 606

see PDF file for more information

 


Herausforderung Tunnelbau 2017
Dipl.-Ing. Fritz Grübl (PSP Consulting Engineers GmbH, München & FH Stuttgart) und Dr.-Ing. Martin Wittke (WBI GmbH, Weinheim)

Die Nutzung des unterirdischen Raums ist ein Schlüsselfaktor für eine nachhaltige Entwicklung sowohl von Industrie-, als auch von Schwellenund Entwicklungsländern. Unterirdische transalpine Verkehrsverbindungen, die Tendenz zu größeren Durchmessern, schwierige geologische Verhältnisse oder hohe Grundwasserdrücke stellen den Tunnelbau und die Vortriebstechnologien vor große Herausforderungen.

Prof. Dipl.-Ing. Fritz Grübl wird in seinem Vortrag auf die Herausforderungen bei der Planung und Herstellung von Tübbingringen für schwierige Bedingungen eingehen. Der Vortrag von Dr.-Ing. Martin Wittke thematisiert moderne Tunnelstatik zur Bemessung der Auskleidung von Tunneln im quellfähigen Gebirge.

please register here for free

Am: 10.11.2017
Um: 15:00
Ort: Veranstaltungszentrum – Saal 1

see PDF file for more information

 


Inverse Analyses and Quasi-Non-Destructive Tests for Identification of both Material Parameters and Residual Stresses
Dr. Aram Cornaggia (Politecnico di Milano, Italy)

Dr. Aram Cornaggia form the Politecnico di Milano, Italy, will hold a guest lecture in the framework of SFB 837 about 'Inverse Analyses and Quasi-Non-Destructive
Tests for Identification of both Material Parameters and Residual Stresses'.

Mechanical characterization of materials and assessment of residual stresses are, at present, subjects of growing interest in engineering for the diagnosis of structural components and structures.
In this talk, some research results will be presented about diagnostic analyses, on the basis of experimental data collected from quasi-non-destructive tests, providing practical advantages, with respect to the present practice, such as reduced damages, times and costs and, possibly, execution in situ. The methodologies presented herein for identifications of parameters are centred, from computational point of view, on inverse analyses based on mechanical and mathematical procedures apt to provide more accurate and reliable parameter estimates. Moreover, stochastic inverse analysis procedures are proposed, based on Kalman filters, for quantification of estimates uncertainty.
The presented practical applications concern metallic structural components and the following combined experiments: Small Punch tests (SP) and specimen extraction (preSP); Hole Drilling (HD) and instrumented Indentation tests (IND). In both cases, an innovative procedure is developed; novelties consist of combined identifications of both material parameters (elastic-plastic, with possible extensions to creep and anisotropic behaviours) and residual stresses, possibly in situ. Consequent reductions of computing times, costs and damages may provide remarkable advantages with respect to the present standardized practices and are evidenced by numerical examples.

Am: 07.11.2017
Um: 15:00
Ort: ID 04 / 471+459

see PDF file for more information