TY  - BOOK
A1  - Staat, Manfred
A1  - Digel, Ilya
A1  - Trzewik, Jürgen
A1  - Sielemann, Stefanie
A1  - Erni, Daniel
A1  - Zylka, Waldemar
T1  - Symposium Proceedings; 4th YRA MedTech Symposium 2024 : February 1 / 2024 / FH Aachen
Y1  - 2024
SN  - 978-3-940402-65-3
U6  - https://doi.org/10.17185/duepublico/81475
PB  - Universität Duisburg-Essen
CY  - Duisburg
ER  - 
TY  - JOUR
A1  - Koch, Christopher
A1  - Böhnisch, Nils
A1  - Verdonck, Hendrik
A1  - Hach, Oliver
A1  - Braun, Carsten
T1  - Comparison of unsteady low- and mid-fidelity propeller aerodynamic methods for whirl flutter applications
JF  - Applied Sciences
N2  - Aircraft configurations with propellers have been drawing more attention in recent times, partly due to new propulsion concepts based on hydrogen fuel cells and electric motors. These configurations are prone to whirl flutter, which is an aeroelastic instability affecting airframes with elastically supported propellers. It commonly needs to be mitigated already during the design phase of such configurations, requiring, among other things, unsteady aerodynamic transfer functions for the propeller. However, no comprehensive assessment of unsteady propeller aerodynamics for aeroelastic analysis is available in the literature. This paper provides a detailed comparison of nine different low- to mid-fidelity aerodynamic methods, demonstrating their impact on linear, unsteady aerodynamics, as well as whirl flutter stability prediction. Quasi-steady and unsteady methods for blade lift with or without coupling to blade element momentum theory are evaluated and compared to mid-fidelity potential flow solvers (UPM and DUST) and classical, derivative-based methods. Time-domain identification of frequency-domain transfer functions for the unsteady propeller hub loads is used to compare the different methods. Predictions of the minimum required pylon stiffness for stability show good agreement among the mid-fidelity methods. The differences in the stability predictions for the low-fidelity methods are higher. Most methods studied yield a more unstable system than classical, derivative-based whirl flutter analysis, indicating that the use of more sophisticated aerodynamic modeling techniques might be required for accurate whirl flutter prediction.
KW  - Aeroelasticity
KW  - Flutter
KW  - Propeller whirl flutter
KW  - Unsteady aerodynamics
KW  - 1P hub loads
Y1  - 2024
U6  - https://doi.org/10.3390/app14020850
SN  - 2076-3417
VL  - 14
IS  - 2
SP  - 1
EP  - 28
PB  - MDPI
CY  - Basel
ER  - 
TY  - CHAP
A1  - Goh, Kheng Lim
A1  - Topçu, Murat
A1  - Madabhushi, Gopal S. P.
A1  - Staat, Manfred
ED  - Maia, Fatima Raquel Azevedo
ED  - Miguel Oliveira, J.
ED  - Reis, Rui L.
T1  - Collagen fibril reinforcement in connective tissue extracellular matrices
T2  - Handbook of the extracellular matrix
N2  - The connective tissues such as tendons contain an extracellular matrix (ECM) comprising collagen fibrils scattered within the ground substance. These fibrils are instrumental in lending mechanical stability to tissues. Unfortunately, our understanding of how collagen fibrils reinforce the ECM remains limited, with no direct experimental evidence substantiating current theories. Earlier theoretical studies on collagen fibril reinforcement in the ECM have relied predominantly on the assumption of uniform cylindrical fibers, which is inadequate for modelling collagen fibrils, which possessed tapered ends. Recently, Topçu and colleagues published a paper in the International Journal of Solids and Structures, presenting a generalized shear-lag theory for the transfer of elastic stress between the matrix and fibers with tapered ends. This paper is a positive step towards comprehending the mechanics of the ECM and makes a valuable contribution to formulating a complete theory of collagen fibril reinforcement in the ECM.
KW  - Connective tissues
KW  - Extracellular matrix (ECM)
KW  - Collagen fibrils
KW  - Mechanical stability
KW  - Tapered ends
Y1  - 2024
SN  - 978-3-031-56362-1 (Print)
SN  - 978-3-031-56363-8 (Online)
U6  - https://doi.org/10.1007/978-3-031-56363-8_6
SP  - 89
EP  - 108
PB  - Springer Nature
CY  - Cham
ER  -