Fak. 5 Verkehrs- und Maschinensysteme

1519 Items

Recent Submissions
Proactive empty vehicle rebalancing for Demand Responsive Transport services

Bischoff, Joschka ; Maciejewski, Michał (2020-04-14)

Worldwide, ridesharing business is steadily growing and has started to receive attention also by public transport operators. With future fleets of Autonomous Vehicles, new business models connecting schedule-based public transport and feeder fleets might become a feasible transport mode. However, such fleets require a good management to warrant a high level of service. One of the key aspects of...

Impacts of vehicle fleet electrification in Sweden – a simulation-based assessment of long-distance trips

Bischoff, Joschka ; Márquez-Fernández, Francisco J. ; Domingues-Olavarría, Gabriel ; Maciejewski, Michał ; Nagel, Kai (2019-06)

Electrifying road transport is seen as one of the key components in decreasing the carbon footprint of the society as a whole. Recent developments in electric drivetrain and battery technology have helped to design vehicles with ranges that make them independent of public charging infrastructure during most sub-urban and commuting trips. Once long-haul trips are planned, however, these vehicles...

The impact of pricing and service area design on the modal shift towards demand responsive transit

Kaddoura, Ihab ; Leich, Gregor ; Nagel, Kai (2020-04-14)

In this study, an agent-based transport simulation is used to look into different design concepts for demand responsive transit (DRT). In different simulation experiments for a real-world case study of the Greater Berlin area, the DRT service area is either set to the inner-city center area or the entire city area, and the DRT pricing scheme is varied. The existing simulation framework is exten...

The effect of unexpected disruptions and information times on public transport passengers: a simulation study

Müller, Sebastian Alexander ; Leich, Gregor ; Nagel, Kai (2020-04-14)

This paper deals with the simulation of unexpected disruptions in public transport in the agent-based transport simulation framework of MATSim. A replanning logic for public transport passengers is implemented so passengers can be informed about and react to a disruption and use an alternative route. An unexpected disruption of an underground line in Berlin is simulated to analyze how passenger...

Potential of Private Autonomous Vehicles for Parcel Delivery

Schlenther, Tilmann ; Martins-Turner, Kai ; Bischoff, Joschka Felix ; Nagel, Kai (2020-09-10)

Using the same vehicles for both passenger and freight transport, to increase vehicle occupancy and decrease their number, is an idea that drives transport planners and is also being addressed by manufacturers. This paper proposes a methodology to simulate the behavior of such vehicles within an urban traffic system and evaluate their performance. The aim is to investigate the impacts of resign...

Hybrid Artificial Intelligence System for the Design of Highly-Automated Production Systems

Hagemann, Simon ; Sünnetcioglu, Atakan ; Stark, Rainer (2019-01-25)

The automated design of production systems is a young field of research which has not been widely explored by industry nor research in recent decades. Currently, the effort spent in production system design is increasing significantly in automotive industry due to the number of product variants and product complexity. Intelligent methods can support engineers in repetitive tasks and give them m...

Finite element analysis of in-situ distortion and bulging for an arbitrarily curved additive manufacturing directed energy deposition geometry

Biegler, Max ; Marko, Angelina ; Graf, Benjamin ; Rethmeier, Michael (2018-10-05)

With the recent rise in the demand for additive manufacturing (AM), the need for reliable simulation tools to support experimental efforts grows steadily. Computational welding mechanics approaches can simulate the AM processes but are generally not validated for AM-specific effects originating from multiple heating and cooling cycles. To increase confidence in the outcomes and to use numerical...

Investigation of liquid metal embrittlement of dual phase steel joints by electro-thermomechanical spot-welding simulation

Frei, Julian ; Biegler, Max ; Rethmeier, Michael ; Böhne, Christoph ; Meschut, Gerson (2019-02-22)

A 3D electro-thermomechanical model is established in order to investigate liquid metal embrittlement. After calibration to a dual phase steel of the 1000 MPa tensile strength class, it is used to analyse the thermo-mechanical system of an experimental procedure to enforce liquid metal embrittlement during resistance spot welding. In this procedure, a tensile stress level is applied to zinc coa...

Sensitivity analysis of the residual stress state in friction stir welding of high strength aluminum alloy

Bachmann, Marcel ; Rethmeier, Michael ; Wu, Chuan Song (2016-01)

In this paper, the friction stir welding process was numerically investigated for 6 mm thick aluminum alloy AA2024-T3. The finite element software COMSOL Multiphysics was used to calculate the transient thermal field during welding and the mechanical reaction depending on different mechanical clamping conditions and hardening models subsequently. A thermal pseudo-mechanical (TPM) heat source wa...

Numerical assessment and experimental verification of the influence of the Hartmann effect in laser beam welding processes by steady magnetic fields

Bachmann, Marcel ; Avilov, Vjaceslav ; Gumenyuk, Andrey ; Rethmeier, Michael (2015-11-18)

Controlling the dynamics in the weld pool is a highly demanding challenge in deep-penetration laser beam welding with modern high power laser systems in the multi kilowatt range. An approach to insert braking forces in the melt which is successfully used in large-scaled industrial applications like casting is the so-called Hartmann effect due to externally applied magnetic fields. Therefore, th...

Calibration-free gaze interfaces based on linear smooth pursuit

Zeng, Zhe ; Siebert, Felix Wilhelm ; Venjakob, Antje Christine ; Rötting, Matthias (2020-02-26)

Since smooth pursuit eye movements can be used without calibration in spontaneous gaze interaction, the intuitiveness of the gaze interface design has been a topic of great interest in the human-computer interaction field. However, since most related research focuses on curved smooth-pursuit trajectories, the design issues of linear trajectories are poorly understood. Hence, this study evaluate...

MODUS-COVID Bericht vom 11.09.2020

Müller, Sebastian Alexander ; Charlton, William ; Conrad, Natasa Djurdjevac ; Ewert, Ricardo ; Conrad, Tim ; Nagel, Kai ; Schütte, Christof (2020-09-11)

Als Reaktion auf die Vielzahl von Aussagen und Regeln bezüglich der Eindämmung von SARS-2, schlagen wir im Bericht vom 11.09.2020 eine systematische Einordnung dieser Regeln vor. Durch eine Art Baukastensystem lassen sich die Wirkungen von Maßnahmen überschlägig berechnen. Darüber hinaus halten wir fest, dass Infektionen in Schulen keinen besonders großen direkten Einfluss auf die Infektionsdyn...

Experimental and numerical assessment of weld pool behavior and final microstructure in wire feed laser beam welding with electromagnetic stirring

Meng, Xiangmeng ; Bachmann, Marcel ; Artinov, Antoni ; Rethmeier, Michael (2019-07-25)

Advantages such as element homogenization and grain refinement can be realized by introducing electromagnetic stirring into laser beam welding. However, the involved weld pool behavior and its direct role on determining the final microstructure have not been revealed quantitatively. In this paper, a 3D transient heat transfer and fluid flow model coupled with element transport and magnetic indu...

Assessment of thermal cycles by combining thermo-fluid dynamics and heat conduction in keyhole mode welding processes

Artinov, Antoni ; Karkhin, Victor ; Khomich, Pavel ; Bachmann, Marcel ; Rethmeier, Michael (2019-07-07)

A numerical framework for simulation of the steady-state thermal behaviour in keyhole mode welding has been developed. It is based on the equivalent heat source concept and consists of two parts: computational thermo-fluid dynamics and heat conduction. The solution of the thermo-fluid dynamics problem by the finite element method for a bounded domain results in a weld pool interface geometry be...

Numerical and experimental investigation of thermo-fluid flow and element transport in electromagnetic stirring enhanced wire feed laser beam welding

Meng, Xiangmeng ; Artinov, Antoni ; Bachmann, Marcel ; Rethmeier, Michael (2019-09-06)

The introduction of electromagnetic stirring to laser beam welding can bring several beneficial effects e.g. element homogenization and grain refinement. However, the underlying physics has not been fully explored due to the absence of quantitative data of heat and mass transfer in the molten pool. In this paper, the influence of electromagnetic stirring on the thermo-fluid flow and element tra...

Avoidance of liquid metal embrittlement during resistance spot welding by heat input dependent hold time adaption

Böhne, Christoph ; Meschut, Gerson ; Biegler, Max ; Rethmeier, Michael (2020-07-20)

Liquid metal embrittlement (LME) cracking can occur during resistance spot welding (RSW) in zinc-coated advanced high-strength steels (AHSS) for automotive production. In this study, a methodological variation of hold time is performed to investigate the process-related crack influence factors. A combination of numerical and experimental investigations confirms, that the extent of heat dissipat...

Stress Tensor and Gradient of Hydrostatic Pressure in the Half-Space Beneath Axisymmetric Bodies in Normal and Tangential Contact

Forsbach, Fabian (2020-06-26)

The stress state in the volume of contacting bodies may essentially influence the material behavior. For evaluating various modes of inelastic behavior and/or failure, such as plastic deformation, crack initiation, and propagation or fatigue, the complete stress tensor beneath the contact interface may be of importance. For many geotechnical and biomechanical applications, the hydrostatic press...

Untersuchung von Diesel-Einspritzkonzepten unter Berücksichtigung von zukünftigen Anforderungen

Frank, Karsten Dieter (2020)

Um die immer neu gesteckten Ziele der positiven Einflussnahme auf die Steigerung der Leistung, die Reduzierung von Kraftstoffverbrauch, Geräusch- und Schadstoffemissionen zu erreichen, werden höhere Ansprüche an das Diesel-Direkteinspritzsystem gestellt. Dies führt zu einem Spannungsfeld von Kosten, Komplexität und Nutzen zwischen dem Einspritz- und dem Abgasnachbehandlungssystem. Für die zukün...

MODUS-COVID Bericht vom 21.08.2020

Rakow, Christian ; Wulkow, Hanna ; Conrad, Natasa Djurdjevac ; Ewert, Ricardo ; Conrad, Tim ; Nagel, Kai ; Schütte, Christof (2020-08-21)

Reiserückkehrer können Infektionen nach Deutschland tragen. Wir betrachten dies in unserem agenten-basierten Modell. Wesentliches Resultat ist, dass der Infektionsimport in derzeitiger Höhe bei den derzeitigen Neuinfektionszahlen einen sehr deutlichen Beitrag leistet, und damit die Maßnahmen, um diesen zu reduzieren, durch die Simulation bestätigt werden. Sogenannten “Superspreading Events” ...

Untersuchungen zu ungeschmiertem Schwingungsverschleiß an 100Cr6-Kugeln gegen 100Cr6-Ebenen

Reichelt, Manuel (2020)

Die vorliegende Doktorarbeit handelt von der Bestimmung vom Verschleißvolumen und vom Verschleißkoeffizienten bei Modellversuchen an 100Cr6-Ebenen und -Kugeln unter Schwingungsbeanspruchung. Es wird in der Tribologie häufig beobachtet, dass der Verschleißkoeffizient, definiert vom Archard-Gesetz als der Proportionalitätsfaktor zwischen dem Verschleißvolumen und dem Produkt aus Normalkraft und ...