Prof. Kiendl's seminar at SISSA

[Emanuele Tuillier Illingworth]

MATHLAB SEMINAR ANNOUNCEMENT


Speaker: Josef Kiendl (University of Pavia)

Date: Wednesday, 13 November, 2013 - 14:00

Room: SISSA - Santorio A - room 133

Abstract: Isogeometric analysis is a recent method of computational 
analysis where functions used to describe geometries in Computer Aided 
Design (CAD) are adopted as basis for analysis. Due to this unified 
geometric representation, the model transfer from design to analysis, 
called mesh generation, is omitted providing a better integration of 
design and analysis. NURBS (Non-Uniform Rational B-Splines) are the most 
widespread technology in today’s CAD modeling tools and therefore are 
adopted as basis functions for analysis. Apart from the geometrical 
advantages, NURBS-based isogeometric analysis has proven superior 
approximation properties compared to standard finite element analysis 
for many different applications due to the higher order and higher 
regularity of the basis functions. Furthermore, the higher continuity 
between elements also allows the implementation of formulations of 
second (or higher) order, which is not possible with C0-continuous 
Lagrange elements. An isogeometric shell element [1] based on the 
Kirchhoff-Love shell theory is presented. The formulation is completely 
displacement-based, i.e., without rotational degrees of freedom. The 
element is formulated geometrically nonlinear and therefore applicable 
to problems with large deformations. Furthermore, a method, called the 
bending strip method [2], is presented which enhances the application of 
this shell formulation to arbitrary structures consisting of multiple 
patches. Different examples show the good performance and accuracy of 
the method, for geometrically linear and nonlinear problems. The 
application in a fully coupled FSI simulation of rotating wind turbine 
blades demonstrates the relevance for realistic industrial structures 
[3]. Furthermore, the fact that both CAD description and shell analysis 
are surface-based, allows an effective integration of design and 
analysis, which is demonstrated by integrating the presented method into 
a commercial CAD software. Moreover, the presented method is extended to 
shape optimization. In traditional shape optimization using FE analysis, 
there are two different approaches for the parametrization of the 
optimization model, namely the CAD-based and the FE-based approach. 
Isogeometric shape optimization is introduced as a combination of and 
enhancement to the existing approaches which provides more flexibility 
in choosing the design space.

[1] Isogeometric shell analysis with Kirchhoff–Love elements, J. Kiendl, 
K.-U. Bletzinger, J. Linhard, and R. Wüchner, Computer Methods in 
Applied Mechanics and Engineering, 198:3902-3914, 2009.

[2] The bending strip method for isogeometric analysis of Kirchhoff–Love 
shell structures comprised of multiple patches, J. Kiendl, Y. Bazilevs, 
M.-C. Hsu, R. Wüchner, K.-U. Bletzinger, Computer Methods in Applied 
Mechanics and Engineering, 199:2403–2416, 2010.

[3] 3D simulation of wind turbine rotors at full scale. Part II: 
Fluid-structure interaction modeling with composite blades, Y. Bazilevs, 
M.-C. Hsu, J. Kiendl, R. Wüchner, and K.-U. Bletzinger, International 
Journal for Numerical Methods in Fluids, 65:236–253, 2011.