Bauhaus University, Weimar

About: Bauhaus University, Weimar is a education organization based out in Weimar, Thüringen, Germany. It is known for research contribution in the topics: Finite element method & Isogeometric analysis. The organization has 1421 authors who have published 2998 publications receiving 104454 citations. The organization is also known as: Bauhaus-Universität Weimar & Hochschule für Architektur und Bauwesen.

Element-wise algorithm for modeling ductile fracture with the Rousselier yield function

Abstract: Within the theme of ductile fracture in metals, we propose an algorithm for FEM-based computational fracture based on edge rotations and smoothing of complementarity conditions. Rotation axes are the crack front nodes in surface discretizations and each rotated edge affects the position of only one or two nodes. Modified edge positions correspond to the predicted crack path. To represent softening, porous plasticity in the form of the Rousselier yield function is used. The finite strain integration algorithm makes use of a consistent updated Lagrangian formulation which makes use of polar decomposition between each increment. Constitutive updating is based on the implicit integration of a regularized non-smooth problem. The proposed alternative is advantageous when compared with enriched elements that can be significantly different than classical FEM elements and still pose challenges for ductile fracture or large amplitude sliding. For history-dependent materials, there are still some transfer of relevant quantities between meshes. However, diffusion of results is more limited than with tip or full remeshing. To illustrate the advantages of our approach, fracture examples making use of the Rousselier yield function are presented. The Ma-Sutton crack path criterion is employed. Traditional fracture benchmarks and newly proposed verification tests are solved. These were found to be very good in terms of crack path and load/displacement accuracy.

Anisotropic mechanical properties and strain tuneable band-gap in single-layer SiP, SiAs, GeP and GeAs

Abstract: Group IV–V-type two-dimensional (2D) materials, such as GeP, GeAs, SiP and SiAs with anisotropic atomic structures , have recently attracted remarkable attention due to their outstanding physics. In this investigation, we conducted density functional theory simulations to explore the mechanical responses of these novel 2D systems. In particular, we explored the possibility of band-gap engineering in these 2D structures through different mechanical loading conditions. First-principles results of uniaxial tensile simulations confirm anisotropic mechanical responses of these novel 2D structures, with considerably higher elastic modulus , tensile strength and stretchability along the zigzag direction as compared with the armchair direction. Notably, the stretchability of considered monolayers along the zigzag direction was found to be slightly higher than that of the single-layer graphene and h-BN. The electronic band-gaps of energy minimized single-layer SiP, SiAs, GeP and GeAs were estimated by HSE06 method to be 2.58 eV, 2.3 eV, 2.24 eV and 1.98 eV, respectively. Our results highlight the strain tuneable band-gap character in single-layer SiP, SiAs, GeP and GeAs and suggest that various mechanical loading conditions can be employed to finely narrow the electronic band-gaps in these structures.

Methods for flutter stability analysis of long-span bridges: a review

Abstract: Predicting the phenomenon of aerodynamic instability is essential for the analysis and design of long-span cable-supported bridges This paper reviews the history and development of aerodynamic analysis techniques and state-of-the-art numerical and experimental methods for flutter stability analysis A discussion of the flutter phenomenon is followed by a literature review This study provides a perspective on self-excited aerodynamic force models, identification of aerodynamic derivatives and methods for determining aerodynamic instability of long-span bridges in two dimensions and three dimensions Computational fluid dynamics (CFD) techniques for modelling the flow past bluff bodies are also covered Different model combination techniques are presented, utilising analytical, numerical and experimental approaches to predict the flutter limit The effect of different parameters on the flutter stability limit is also highlighted Furthermore, an overview of the complementary relationship between wind tunn

A review of experimental and analytical studies on the out-of-plane behaviour of masonry infilled frames

Abstract: This paper presents a literature review of research undertaken on the out-of-plane behaviour of masonry infilled frames. This paper also discusses the effects of bidirectional loads, openings, slenderness, boundary conditions etc. As numerous researchers have reported, these effects play a crucial role in achieving arching action cause, as they can bypass or limit its effectiveness. Namely, arching action leads to additional compressive forces which resist traversal ones. This is confirmed by inertial force methods of testing, while the same cannot be claimed for inter-storey drift or dynamical methods. It is to be acknowledged that most experimental tests were carried out using inertial force methods, mostly with the use of airbags. In contrast, only a few were undertaken with dynamical methods and just two with inter-storey drift methods. It was found that inertial force and inter-storey drift methods differ widely. In particular, inertial force methods damage the infill, leaving the frame more or less intact. Conversely, drift heavily damages the frame, while infill only slightly. Openings were investigated, albeit with contrasting results. Namely, in all cases, it was found that openings do lower the deformational but not all load-bearing capacities. Furthermore, analytical models have shown contrasting results between themselves and with experimental data. Models’ stabilities were checked with single- and multi-variable parametric analysis from which governing factors, influences of frame and other parameters were identified.