TY - GEN A1 - Noack, Martin A1 - Kühhorn, Arnold A1 - Kober, Markus A1 - Firl, Matthias T1 - A new stress-based topology optimization approach for finding flexible structures T2 - Structural and Multidisciplinary Optimization N2 - This paper presents a new FE-based stress-related topology optimization approach for finding bending governed flexible designs. Thereby, the knowledge about an output displacement or force as well as the detailed mounting position is not necessary for the application. The newly developed objective function makes use of the varying stress distribution in the cross section of flexible structures. Hence, each element of the design space must be evaluated with respect to its stress state. Therefore, the method prefers elements experiencing a bending or shear load over elements which are mainly subjected to membrane stresses. In order to determine the stress state of the elements, we use the principal stresses at the Gauss points. For demonstrating the feasibility of the new topology optimization approach, three academic examples are presented and discussed. As a result, the developed sensitivity-based algorithm is able to find usable flexible design concepts with a nearly discrete 0 − 1 density distribution for these examples. KW - Topology optimization KW - Flexible structure KW - Stress-based KW - SIMP KW - Conceptual design Y1 - 2021 U6 - https://doi.org/10.1007/s00158-021-02960-w SN - 1615-147X SN - 1615-1488 VL - 64 IS - 4 SP - 1997 EP - 2007 ER - TY - GEN A1 - Gambitta, Marco A1 - Kühhorn, Arnold A1 - Beirow, Bernd A1 - Schrape, Sven T1 - Stator Blades Manufacturing Geometrical Variability in Axial Compressors and Impact on the Aeroelastic Excitation Forces T2 - Journal of Turbomachinery N2 - The manufacturing geometrical variability is a source of uncertainty, which cannot be avoided in the realization of machinery components. Deviations of a part geometry from its nominal design are inevitably present due to the manufacturing process. In the case of the aeroelastic forced response problem within axial compressors, these uncertainties may affect the vibration characteristics. For this reason, the impact of geometrical uncertainties due to the manufacturing process onto the modal forcing of axial compressor blades is investigated in this study. The research focuses on the vibrational behavior of an axial compressor rotor blisk. In particular, the amplitude of the forces acting as a source of excitation on the vibrating blades is studied. The geometrical variability of the upstream stator is investigated as input uncertainty. The variability is modeled starting from a series of optical surface scans. A stochastic model is created to represent the measured manufacturing geometrical deviations from the nominal model. A data reduction methodology is proposed in order to represent the uncertainty with a minimal set of variables. The manufacturing geometrical variability model allows to represent the input uncertainty and probabilistically evaluate its impact on the aeroelastic problem. An uncertainty quantification is performed in order to evaluate the resulting variability on the modal forcing acting on the vibrating rotor blades. Of particular interest is the possible rise of low engine orders due to the mistuned flow field along the annulus. A reconstruction algorithm allows the representation of the variability during one rotor revolution. The uncertainty on low harmonics of the modal rotor forcing can be therefore identified and quantified. KW - aeromechanical instabilities KW - computational fluid dynamics (CFD) KW - turbomachinery blading design Y1 - 2022 U6 - https://doi.org/10.1115/1.4052602 SN - 1528-8900 VL - 144 ER -