Computationally efficient reduction of modal data from finite element models by nested sets of B-splines

摘要

This paper introduces a novel methodology for the reduction of modal data from complex finite element\ud(FE) models, resulting in a highly accurate and computationally efficient model termed B-SAFE (B-splinebased\udSemi-Analytical Finite Element model). It is conceptually similar to a method based on nested sets\udof polynomials proposed earlier by the authors (Poly-SAFE) but provides greater accuracy in the case of\udcomplex structures and greater ease of use, limiting the need for user interventions and facilitating automated\udprocessing. B-SAFE is constructed via the reduction of a standard displacement-based FE model\uddown to a semi-analytical function built from nested B-splines recursively fitted to modal data, which\udeliminates the need of high-order polynomials and heavy user-intervention required by Poly-SAFE for\udthe case of complex modal patterns. The present work describes the non-trivial modifications to the original\udmethodology, and shows how fewer and more efficient semi-analytical functions representing field\udvariables such as displacement, strain and stress can be obtained. The new method is exemplified\udthrough a numerical case study of a 9.2 m composite wind turbine blade, showing that improved numerical\udstability and robustness as well as a systematic handling of general geometries can be obtained without\uduser intervention.