@article{MatheisRoethWagner2005, author = {Matheis, Anton and R{\"o}th, Thilo and Wagner, Manfred}, title = {Studentenprojekt "Capro" - eine virtuelle Sportwagenstudie "Vision 2015"}, year = {2005}, abstract = {Design- und Karosseriebaustudenten der FH Aachen entwickeln gemeinsam mit externen Fachleuten unter Einsatz virtueller Entwicklungswerkzeuge ein Konzept f{\"u}r einen Sportwagen}, subject = {Karosseriebau}, language = {de} } @inproceedings{Mertens2000, author = {Mertens, Josef}, title = {Laminar leading edges: manufacturing, contamination, and operational aspects - results from the German RaWid programme}, year = {2000}, abstract = {RaWid was the German national technology programme on transonic aerodynamics and supporting technologies, lasting from 1995 to 1998. One of the main topics was laminar wing development. Besides aerodynamic design work, many operational aspects were investigated. A manufacturing concept was developed to be applied to operational laminar wings and empennages. It was built in a large scale manufacturing demonstrator with the aerodynamic shape of a 1,5 m section of the A320 fin nose. Tolerances in shape and roughness fulfilled all requirements. The construction can easily be adapted to varying stiffness and strength requirements. Weight and manufacturing costs are comparable to common nose designs. The mock-up to be designed in ALTTA is based on this manufacturing principle. Another critical point is contamination of suction surfaces. Several tests were performed to investigate perforated titanium suction surfaces at realistic operational conditions: - a one year flight test with a suction plate in the stagnation area of the Airbus "Beluga" - a one year test of several suction plates in a ground test near the airport - a one year test of a working suction ground test installation at all weather conditions. No critical results were found. There is no long term suction degradation visible. Icing conditions and ground de-icing fluids used on airports did not pose severe problems. Some problems detected require only respection of weak design constraints.}, subject = {Laminare Str{\"o}mung}, language = {en} } @article{MoehrenBergmannJanseretal.2023, author = {M{\"o}hren, Felix and Bergmann, Ole and Janser, Frank and Braun, Carsten}, title = {On the influence of elasticity on propeller performance: a parametric study}, series = {CEAS Aeronautical Journal}, volume = {14}, journal = {CEAS Aeronautical Journal}, publisher = {Springer Nature}, address = {Berlin}, issn = {1869-5590 (Online)}, doi = {10.1007/s13272-023-00649-y}, pages = {311 -- 323}, year = {2023}, abstract = {The aerodynamic performance of propellers strongly depends on their geometry and, consequently, on aeroelastic deformations. Knowledge of the extent of the impact is crucial for overall aircraft performance. An integrated simulation environment for steady aeroelastic propeller simulations is presented. The simulation environment is applied to determine the impact of elastic deformations on the aerodynamic propeller performance. The aerodynamic module includes a blade element momentum approach to calculate aerodynamic loads. The structural module is based on finite beam elements, according to Timoshenko theory, including moderate deflections. Several fixed-pitch propellers with thin-walled cross sections made of both isotropic and non-isotropic materials are investigated. The essential parameters are varied: diameter, disc loading, sweep, material, rotational, and flight velocity. The relative change of thrust between rigid and elastic blades quantifies the impact of propeller elasticity. Swept propellers of large diameters or low disc loadings can decrease the thrust significantly. High flight velocities and low material stiffness amplify this tendency. Performance calculations without consideration of propeller elasticity can lead to decreased efficiency. To avoid cost- and time-intense redesigns, propeller elasticity should be considered for swept planforms and low disc loadings.}, language = {en} } @article{MoehrenBergmannJanseretal.2024, author = {M{\"o}hren, Felix and Bergmann, Ole and Janser, Frank and Braun, Carsten}, title = {Assessment of structural mechanical effects related to torsional deformations of propellers}, series = {CEAS Aeronautical Journal}, journal = {CEAS Aeronautical Journal}, publisher = {Springer}, address = {Wien}, issn = {1869-5590 (eISSN)}, doi = {10.1007/s13272-024-00737-7}, pages = {22 Seiten}, year = {2024}, abstract = {Lifting propellers are of increasing interest for Advanced Air Mobility. All propellers and rotors are initially twisted beams, showing significant extension-twist coupling and centrifugal twisting. Torsional deformations severely impact aerodynamic performance. This paper presents a novel approach to assess different reasons for torsional deformations. A reduced-order model runs large parameter sweeps with algebraic formulations and numerical solution procedures. Generic beams represent three different propeller types for General Aviation, Commercial Aviation, and Advanced Air Mobility. Simulations include solid and hollow cross-sections made of aluminum, steel, and carbon fiber-reinforced polymer. The investigation shows that centrifugal twisting moments depend on both the elastic and initial twist. The determination of the centrifugal twisting moment solely based on the initial twist suffers from errors exceeding 5\% in some cases. The nonlinear parts of the torsional rigidity do not significantly impact the overall torsional rigidity for the investigated propeller types. The extension-twist coupling related to the initial and elastic twist in combination with tension forces significantly impacts the net cross-sectional torsional loads. While the increase in torsional stiffness due to initial twist contributes to the overall stiffness for General and Commercial Aviation propellers, its contribution to the lift propeller's stiffness is limited. The paper closes with the presentation of approximations for each effect identified as significant. Numerical evaluations are necessary to determine each effect for inhomogeneous cross-sections made of anisotropic material.}, language = {en} } @misc{Roeth2004, author = {R{\"o}th, Thilo}, title = {Leichtbau und Karosserietechnik}, year = {2004}, abstract = {Studienschwerpunkt Leichtbau und Karosserietechnik an der FH Aachen, Grobstruktur der Lehrinhalte, Studentenprojekt "CAPRO"}, subject = {Leichtbau}, language = {de} } @inproceedings{Roeth2002, author = {R{\"o}th, Thilo}, title = {Modularisierung in der Karosserie von morgen}, year = {2002}, abstract = {1) Module werden die Fahrzeugplattform und den -aufbau in Zukunft weiterhin und in zunehmendem Maße bestimmen. 2) Neue Module und Modulschnittstellen am Fahrzeug werden {\"u}berdacht und k{\"o}nnen in der Zukunft erwartet werden. 3) Die Wertsch{\"o}pfung und der Entwicklungsumfang wird sich vom OEM zum Modullieferanten verlagern. 4) Modulvergaben werden in der Zukunft noch st{\"a}rker auf Innovation und Kostenreduktion beruhen. 5) Modularisierung des Fahrzeuges heißt ein Aufbrechen der Fahrzeugkarosserie und wird daher von der Beherrschung struktureller Aufgaben sowie der L{\"o}sung der (sichtbaren) Modul{\"u}berg{\"a}nge bestimmt sein. 6) Neben den Systemintegratoren und den Komponentenspezialisten besetzen die Modullieferanten die erste Lieferantenriege. 7) Der Modullieferant wird neben h{\"o}chster Fertigungsexpertise ein hohes Maß an (Teil-)fahrzeug-Know-How und Produktentwickler-mentalit{\"a}t bereitstellen.}, subject = {Karosseriebau}, language = {de} } @inproceedings{RoethTragsdorf2004, author = {R{\"o}th, Thilo and Tragsdorf, Carsten}, title = {Innovativer Einsatz von Werkstoffen - Trends und Entwicklungen im Karosserieleichtbau}, year = {2004}, abstract = {1) In Karosseriestrukturen steht der richtige Werkstoffeinsatz st{\"a}rker den je im Spannungsfeld von Leichtbau, Kosten (St{\"u}ckzahlen) und Leistungsanforderung 2) In „klassischen" Strukturen von Modultr{\"a}gern und Klappen hat sich die Materialmischbauweise verst{\"a}rkt in den letzten Jahren durchgesetzt 3) Unter Aspekten des konzeptionellen Leichtbaus erscheint der verst{\"a}rkte Einsatz von Leichtbauwerkstoffen im Vorderwagen sowie in der Dachstruktur zielf{\"u}hrend 4) Offene Strukturprofile in Materialmischbauweise liefern f{\"u}r eine Vielzahl von Anwendungen ein interessantes und bis dato kaum genutztes Potential 5) Neue Entwicklungen bei den F{\"u}getechnologien (i.b. kontinuierliche F{\"u}geverbindungen und kombinierte Verfahren) unterst{\"u}tzen den wirtschaftlichen Karosserieleichtbau 6) Werkstoffinnovationen sowie neuartige Fertigungsverfahren machen den Konstruktionswerkstoff „Stahl" auch in der Zukunft im Karosseriebau weiterhin sehr attraktiv}, subject = {Karosseriebau}, language = {de} } @article{ThomaGardiFisheretal.2024, author = {Thoma, Andreas and Gardi, Alessandro and Fisher, Alex and Braun, Carsten}, title = {Improving local path planning for UAV flight in challenging environments by refining cost function weights}, series = {CEAS Aeronautical Journal}, journal = {CEAS Aeronautical Journal}, publisher = {Springer}, address = {Wien}, issn = {1869-5590 (eISSN)}, doi = {10.1007/s13272-024-00741-x}, pages = {12 Seiten}, year = {2024}, abstract = {Unmanned Aerial Vehicles (UAV) constantly gain in versatility. However, more reliable path planning algorithms are required until full autonomous UAV operation is possible. This work investigates the algorithm 3DVFH* and analyses its dependency on its cost function weights in 2400 environments. The analysis shows that the 3DVFH* can find a suitable path in every environment. However, a particular type of environment requires a specific choice of cost function weights. For minimal failure, probability interdependencies between the weights of the cost function have to be considered. This dependency reduces the number of control parameters and simplifies the usage of the 3DVFH*. Weights for costs associated with vertical evasion (pitch cost) and vicinity to obstacles (obstacle cost) have the highest influence on the failure probability of the local path planner. Environments with mainly very tall buildings (like large American city centres) require a preference for horizontal avoidance manoeuvres (achieved with high pitch cost weights). In contrast, environments with medium-to-low buildings (like European city centres) benefit from vertical avoidance manoeuvres (achieved with low pitch cost weights). The cost of the vicinity to obstacles also plays an essential role and must be chosen adequately for the environment. Choosing these two weights ideal is sufficient to reduce the failure probability below 10\%.}, language = {en} } @article{ThomessenThomaBraun2023, author = {Thomessen, Karolin and Thoma, Andreas and Braun, Carsten}, title = {Bio-inspired altitude changing extension to the 3DVFH* local obstacle avoidance algorithm}, series = {CEAS Aeronautical Journal}, journal = {CEAS Aeronautical Journal}, publisher = {Springer}, address = {Wien}, issn = {1869-5590 (Online)}, doi = {10.1007/s13272-023-00691-w}, pages = {11 Seiten}, year = {2023}, abstract = {Obstacle avoidance is critical for unmanned aerial vehicles (UAVs) operating autonomously. Obstacle avoidance algorithms either rely on global environment data or local sensor data. Local path planners react to unforeseen objects and plan purely on local sensor information. Similarly, animals need to find feasible paths based on local information about their surroundings. Therefore, their behavior is a valuable source of inspiration for path planning. Bumblebees tend to fly vertically over far-away obstacles and horizontally around close ones, implying two zones for different flight strategies depending on the distance to obstacles. This work enhances the local path planner 3DVFH* with this bio-inspired strategy. The algorithm alters the goal-driven function of the 3DVFH* to climb-preferring if obstacles are far away. Prior experiments with bumblebees led to two definitions of flight zone limits depending on the distance to obstacles, leading to two algorithm variants. Both variants reduce the probability of not reaching the goal of a 3DVFH* implementation in Matlab/Simulink. The best variant, 3DVFH*b-b, reduces this probability from 70.7 to 18.6\% in city-like worlds using a strong vertical evasion strategy. Energy consumption is higher, and flight paths are longer compared to the algorithm version with pronounced horizontal evasion tendency. A parameter study analyzes the effect of different weighting factors in the cost function. The best parameter combination shows a failure probability of 6.9\% in city-like worlds and reduces energy consumption by 28\%. Our findings demonstrate the potential of bio-inspired approaches for improving the performance of local path planning algorithms for UAV.}, language = {en} }