TY - JOUR A1 - Nanthakumar, S.S. A1 - Lahmer, Tom A1 - Zhuang, Xiaoying A1 - Zi, Goangseup A1 - Rabczuk, Timon T1 - Detection of material interfaces using a regularized level set method in piezoelectric structures JF - Inverse Problems in Science and Engineering N2 - Detection of material interfaces using a regularized level set method in piezoelectric structures KW - Angewandte Mathematik KW - Stochastik KW - Strukturmechanik Y1 - 2016 SP - 153 EP - 176 ER - TY - JOUR A1 - Nanthakumar, S.S. A1 - Lahmer, Tom A1 - Zhuang, Xiaoying A1 - Zi, Goangseup A1 - Rabczuk, Timon T1 - Detection of material interfaces using a regularized level set method in piezoelectric structures JF - Inverse Problems in Science and Engineering N2 - Detection of material interfaces using a regularized level set method in piezoelectric structures KW - Angewandte Mathematik KW - Stochastik KW - Strukturmechanik Y1 - 2015 ER - TY - JOUR A1 - Nguyen-Tuan, Long A1 - Könke, Carsten A1 - Bettzieche, Volker A1 - Lahmer, Tom T1 - Numerical modeling and validation for 3D coupled-nonlinear thermo-hydro-mechanical problems in masonry dams JF - Computers & Structures N2 - Numerical modeling and validation for 3D coupled-nonlinear thermo-hydro-mechanical problems in masonry dams KW - Angewandte Mathematik KW - Stochastik KW - Strukturmechanik Y1 - 2017 SP - 143 EP - 154 ER - TY - JOUR A1 - Nguyen-Tuan, Long A1 - Lahmer, Tom A1 - Datcheva, Maria A1 - Schanz, Tom T1 - Global and local sensitivity analyses for coupled thermo‐hydro‐mechanical problems JF - International Journal for Numerical and Analytical Methods in Geomechanics N2 - Global and local sensitivity analyses for coupled thermo‐hydro‐mechanical problems KW - Angewandte Mathematik KW - Stochastik KW - Strukturmechanik Y1 - 2016 ER - TY - JOUR A1 - Nguyen-Tuan, Long A1 - Lahmer, Tom A1 - Datcheva, Maria A1 - Stoimenova, Eugenia A1 - Schanz, Tom T1 - A novel parameter identification approach for buffer elements involving complex coupled thermo-hydro-mechanical analyses JF - Computers and Geotechnics N2 - A novel parameter identification approach for buffer elements involving complex coupled thermo-hydro-mechanical analyses KW - Angewandte Mathematik KW - Stochastik KW - Strukturmechanik Y1 - 2016 SP - 23 EP - 32 ER - TY - JOUR A1 - Nguyen-Vinh, H. A1 - Bakar, I. A1 - Msekh, Mohammed Abdulrazzak A1 - Song, Jeong-Hoon A1 - Muthu, Jacob A1 - Zi, Goangseup A1 - Le, P. A1 - Bordas, Stéphane Pierre Alain A1 - Simpson, R. A1 - Natarajan, S. A1 - Lahmer, Tom A1 - Rabczuk, Timon T1 - Extended Finite Element Method for Dynamic Fracture of Piezo-Electric Materials JF - Engineering Fracture Mechanics N2 - We present an extended finite element formulation for dynamic fracture of piezo-electric materials. The method is developed in the context of linear elastic fracture mechanics. It is applied to mode I and mixed mode-fracture for quasi-steady cracks. An implicit time integration scheme is exploited. The results are compared to results obtained with the boundary element method and show excellent agreement. KW - Angewandte Mathematik KW - Stochastik KW - Strukturmechanik Y1 - 2012 U6 - http://dx.doi.org/10.1016/j.engfracmech.2012.04.025 SP - 19 EP - 31 ER - TY - JOUR A1 - Schmidt, Albrecht A1 - Lahmer, Tom T1 - Efficient domain decomposition based reliability analysis for polymorphic uncertain material parameters JF - Proceedings in Applied Mathematics & Mechanics N2 - Realistic uncertainty description incorporating aleatoric and epistemic uncertainties can be described within the framework of polymorphic uncertainty, which is computationally demanding. Utilizing a domain decomposition approach for random field based uncertainty models the proposed level-based sampling method can reduce these computational costs significantly and shows good agreement with a standard sampling technique. While 2-level configurations tend to get unstable with decreasing sampling density 3-level setups show encouraging results for the investigated reliability analysis of a structural unit square. KW - Polymorphie KW - Stoffeigenschaft KW - Stochastik KW - polymorphe Unschärfemodellierung KW - Materialverhalten KW - hybride Werkstoffe Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20220112-45563 UR - https://onlinelibrary.wiley.com/doi/full/10.1002/pamm.202100014 VL - 2021 IS - Volume 21, issue 1 SP - 1 EP - 4 PB - Wiley-VHC CY - Weinheim ER - TY - THES A1 - Schorling, York T1 - Beitrag zur Stabilitätsuntersuchung von Strukturen mit räumlich korrelierten geometrischen Imperfektionen N2 - Für geometrisch imperfekte Strukturen wird die Versagenswahrscheinlichkeit bezüglich Stabilitätskriterien bestimmt. Eine probabilistische Beschreibung der geometrischen Imperfektionen erfolgt mit skalaren ortsdiskretisierten Zufallsfeldern. Die Stabilitätsberechnungen werden mit der Finite Elemente Methode durchgeführt. Ausgangspunkt der Berechnung ist eine systematische Formulierung probabilistisch gewichteter Imperfektionsformen durch eine Eigenwertzerlegung der Kovarianzmatrix. Wenn mit einer strukturmechanisch orientierten Sensitivitätsanalyse ein Unterraum zur näherungsweisen Beschreibung des probabilistischen Strukturverhaltens gefunden wird, kann die Versagenswahrscheinlichkeit numerisch sehr effizient durch ein Interaktionsmodell bestimmt werden. Es zeigte sich, daß dies genau dann möglich ist, wenn die Beulform merklich im Imperfektionsfeld enthalten ist. Die Imperfektionsform am Bemessungspunkt entspricht dann, unabhängig vom Lastniveau, gerade der Beulform. Wenn die Beulform im Imperfektionsfeld einen untergeordneten Beitrag liefert, erscheint eine Reduktion des stochastischen Problems auf wenige Zufallsvariablen dagegen nicht möglich. N2 - The thesis presents a concept for reliability analysis of geometrical imperfect structures with respect to static stability criteria. The geometrical imperfections are modeled as Gaussian random fields. The structural analysis is based on the Finite Element Method. A spectral decomposition of the covariance matrix, enables to formulate independent probabilistically weighted imperfections shapes, which may be analyzed by means of structural mechanics. Reliability calculations with procedures such as the response surface method require the reduction of the random variable space. Examples proved that a suitable definition of a subspace of the random variable space is possible, if the buckling shapes are sufficiently included in the random field. In this case the imperfection shape is-independent of the load level-identical to the buckling shape. In contrast if the buckling shapes are not included in the random field, the structure shows a wide banded behavior. Consequently a reduction of the variable space and the application of an interaction models is then not feasible for the determination of the failure probabilty. KW - Tragwerk KW - Formabweichung KW - Stabilität KW - Beulung KW - Zuverlässigkeit KW - Finite-Elemente-Methode KW - Imperfektion KW - Berechnung KW - Stochastik KW - Zufallsfeld Y1 - 1997 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20040216-317 ER - TY - JOUR A1 - Stein, Peter A1 - Lahmer, Tom A1 - Bock, Sebastian T1 - Synthese und Analyse von gekoppelten Modellen im konstruktiven Ingenieurbau BT - Sonderdruck‐DFG Graduiertenkolleg JF - Bautechnik N2 - Synthese und Analyse von gekoppelten Modellen im konstruktiven Ingenieurbau KW - Angewandte Mathematik KW - Stochastik KW - Strukturmechanik Y1 - 2011 SP - 8 EP - 11 ER - TY - JOUR A1 - Vu-Bac, N. A1 - Lahmer, Tom A1 - Keitel, Holger A1 - Zhao, Jun-Hua A1 - Zhuang, Xiaoying A1 - Rabczuk, Timon T1 - Stochastic predictions of bulk properties of amorphous polyethylene based on molecular dynamics simulations JF - Mechanics of Materials N2 - Stochastic predictions of bulk properties of amorphous polyethylene based on molecular dynamics simulations KW - Angewandte Mathematik KW - Stochastik KW - Strukturmechanik Y1 - 2014 SP - 70 EP - 84 ER -