Events

EU Regional School - Fritzen Seminar

Location: AICES Seminar Room 115, 1st floor, Schinkelstr. 2, 52062 Aachen

Dr. Felix Fritzen - Model Order Reduction and Data-assisted Surrogates in Materials Science

 

Abstract

In engineering applications the use of manufactured or natural composite materials is a key technology enabling leight-weight constructions and outstanding physical properties. However, the prediction of the impact of changes of the microstructural configuration on the physical properties are nontrivial to foresee. In order to better understand the microstructure-property relations, the use of model order reduction can be of great use. First, it enables parametric studies that account for deviations of the phase properties. Second, it allows for the consideration of nonlinearities at a fraction of the compute time of fully resolved models. The link between model reduction and computational homogenization in linear and nonlinear settings will be explored in this lecture. Further, the use of state of the art data-assisted techniques for the surrogation of nonlinear material models will be discussed. Here the use of reduced order models for the generation of the samples of the full order model are found to be rather useful.

EU Regional School - Geuzaine Seminar

Location: AICES Seminar Room 115, 1st floor, Schinkelstr. 2, 52062 Aachen

Prof. Christoph Geuzaine, Ph.D. - Recent Developments in Gmsh

Department of Electrical Engineering and Computer Science, University of Liege, Belgium

Abstract

Gmsh (http://gmsh.info) is an open source finite element mesh generator with built-in pre- and post-processing facilities. Under continuous development for the last two decades, it has become the de facto standard for open source finite element mesh generation, with a large user community in both academia and industry. In this talk I will present an overview of Gmsh, and highlight recent developments including the support for constructive solid geometry, new robust and parallel meshing algorithms, flexible solver integration and a new multi-language Application Programming Interface. Time permitting I will also present an overview of current research directions for meshing based on the solution of partial differential equations: from surface remeshing to frame-based hex-meshing.

EU Regional School - Uciński Seminar

Location: AICES Seminar Room 115, 1st floor, Schinkelstr. 2, 52062 Aachen

Prof. Dariusz Uciński Ph.D. - Optimum Experimental Design for Distributed Parameter System Identification

Institute of Control and Computation Engineering, University of Zielona Góra, Poland

Abstract

The impossibility of observing the states of distributed parameter systems over the entire spatial domain raises the question of where to locate measurement sensors so as to estimate the unknown system parameters as accurately as possible. Both researchers and practitioners do not doubt that making use of sensors placed in an ‘intelligent’ manner may lead to dramatic gains in the achievable accuracy of the parameter estimates, so efficient sensor location strategies are highly desirable. In turn, the complexity of the sensor location problem implies that there are few sensor placement methods which are readily applicable to practical situations. What is more, they are not well known among researchers. The aim of the minicourse is to give account of both classical and recent original work on optimal sensor placement strategies for parameter identification in dynamic distributed systems modeled by partial differential equations. The reported work constitutes an attempt to meet the needs created by practical applications, especially regarding environmental processes, through the development of new techniques and algorithms or adopting methods which have been successful in akin fields of optimal control and optimum experimental design. While planning, real-valued functions of the Fisher information matrix of parameters are primarily employed as the performance indices to be minimized with respect to the sensor positions. Particular emphasis is placed on determining the ‘best’ way to guide moving and scanning sensors, and making the solutions independent of the parameters to be identified. A couple of case studies regarding the design of air quality monitoring networks are adopted as an illustration aiming at showing the strength of the proposed approach in studying practical problems. The course will be complemented by a discussion of more advanced topics including the related problem of optimum input design and the Bayesian approach to deal with the ill-posedness of parameter estimation.

 

EU Regional School - Kiendl Seminar

Location: AICES Seminar Room 115, 1st floor, Schinkelstr. 2, 52062 Aachen

Prof. Dr. Josef Kiendl - Structural Analysis of Shells: Geometry, Mechanics, and Computational Methods

Department of Marine Technology, Norwegian University of Science and Technology, Norway

Abstract

Shell structures are ubiquitous in engineering and nature as they provide a very high ratio of stiffness to weight. Their structural behavior is mainly determined by their shape, and geometry plays a fundamental role in establishing the equations for shell mechanics. In practice, structural analysis is performed mainly through numerical methods like finite element analysis and there have been decades of research for developing efficient and robust shell elements. Isogeometric Analysis, which aims at combining computer-aided geometric design and analysis, has shown to be especially well-suited for shell analysis and has led to a new wave of research on shell element formulations.

In this lecture, we will first discuss the theory of shell structures, starting with an introduction to differential geometry and then deriving the governing equations in strong and weak forms. Based on that, we will discuss their solution with numerical methods and consider different element formulations from FEA and IGA. Finally, some applications from actual research within isogeometric shell analysis will be presented.

SSD - Elber Seminar

Location: AICES Seminar Room 115, 1st floor, Schinkelstr. 2, 52062 Aachen

Prof.Gershon Elber, Ph.D. - Volumetric Representations: the Geometric Modeling of the Next Generation

Computer Science Department, Technion - Israel Institute of Technology, Israel
 

Abstract

The needs of modern (additive) manufacturing (AM) technologies can be satisfied no longer by boundary representations (B-reps), as AM requires the representation and manipulation of interior fields and materials as well. Further, while the need for a tight coupling between design and analysis has been recognized as crucial almost since geometric modeling (GM) has been conceived, contemporary GM systems only offer a loose link between the two, if at all.

For about half a century, (trimmed) Non Uniform Rational B-spline (NURBs) surfaces has been the B-rep of choice for virtually all the GM industry. Fundamentally, B-rep GM has evolved little during this period. In this talk, we seek to examine an extended volumetric representation (V-rep) that successfully confronts the existing and anticipated design, analysis, and manufacturing foreseen challenges. We extend all fundamental B-rep GM operations, such as primitive and
surface constructors and Boolean operations, to trimmed trivariate V-reps. This enables the much needed tight link to (Isogeometric) analysis on one hand and the full support of (heterogeneous and anisotropic) additive manufacturing on the other.

Examples and other applications of V-rep GM, including AM and lattice- and micro-structure synthesis and heterogeneous materials will also be demonstrated.