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Dissertation
Multi-Robot Task Allocation for Inspection Problems with Cooperative Tasks Using Hybrid Genetic Algorithms
(kassel university press, 2014)
In dieser Dissertation werden Methoden zur optimalen Aufgabenverteilung in Multirobotersystemen (engl. Multi-Robot Task Allocation – MRTA) zur Inspektion von Industrieanlagen untersucht. MRTA umfasst die Verteilung und Ablaufplanung von Aufgaben für eine Gruppe von Robotern unter Berücksichtigung von operativen Randbedingungen mit dem Ziel, die
Gesamteinsatzkosten zu minimieren. Dank zunehmendem technischen Fortschritt und sinkenden Technologiekosten ist das Interesse an mobilen Robotern für den Industrieeinsatz ...
Dissertation
Analyse und numerische Simulation von freien Oberflächenwellen in der Gießkammer eines Druckgießprozesses
(kassel university press, 2015)
Die Ausbreitung von Oberflächenwellen an der Phasengrenzfläche zwischen einer Flüssigkeit und einem Gas kommt sowohl in der Natur als auch in der Technik häufig vor.
In zeitabhängigen Prozessen ist die freie Oberfläche in der Regel nicht fest, sondern sie ändert ihre Lage in Abhängigkeit von Ort und Zeit. Zur Prognose der Strömung selbst sowie für die entstehenden Kräfte und Momente ist es daher erforderlich, die Bewegung der freien Oberfläche simultan zu bestimmen. Unter stark einschränkenden Bedingungen, z. B. ...
Dissertation
Numerical and experimental response and stability investigations of anisotropic rotor-bearing systems
(kassel university press, 2010)
Buch
Modellierung und Simulation viskoelastischer Polymerschmelzen
(kassel university press, 2012)
Die vorliegende Dissertation behandelt Kunststoffschmelzen als viskoelastische Fluide, bzw. im allgemeinen als Nicht-Newtonsche Fluide. Schmelzen dieser Art zeigen in der Tat viskoelastisches Verhalten, aber auch u.a. Strukturviskosität bzw. Scherentzähung und
Normalspannungsdifferenzen.
Diese Fülle an verschiedenen, beobachtbaren Phänomene werden mit linearen Ansätzen nicht mehr ausreichend beschrieben. In dieser Arbeit werden Modelle eingesetzt, die auf makroskopischen und mikroskopischen Konzepten basieren. Dazu ...
Aufsatz
Cyclic degradation of Co49Ni21Ga30 high-temperature shape memory alloy - On the roles of dislocation activity and chemical order
(2015)
Conventional shape memory alloys (SMAs), such as binary Ni-Ti, are typically limited to service temperatures below 100 °C. Recent studies on Co-Ni-Ga high temperature (HT) SMAs revealed the potential that these alloys can be used up to temperatures of about 400 °C. Analysis of the cyclic functional properties showed that degradation in these alloys is mainly triggered by intensive dislocation motion. However, data on the cyclic stress-strain response and the mechanisms leading to functional degradation of Co-Ni-Ga ...
Konferenzveröffentlichung
Multicomponent Injection Molding Of Thermoplastics And Liquid Silicone Rubber (LSR) – Either Cured By Heat Or UV Light
(Society of Plastics Engineers, 2016)
For processing thermally curing liquid silicone rubber (LSR) as well as UV light curing LSR for multicompo-nent injection molding with thermoplastics in an compa-rable way a processing center was designed and set into operation.
For the production of the multicomponent specimens a modular tool was designed. In there a thermoplastic plate gets molded on the one side, then gets transferred auto-matically by a robot system and gets overmolded by the silicone on the other side. The complete silicone side of the tool is ...
Aufsatz
On the Effect of Quenching on Postweld Heat Treatment of Friction-Stir-Welded Aluminum 7075 Alloy
(2019)
This work focuses on the effect of postweld heat treatment (PWHT) on the mechanical properties and microstructural evolution of aluminum 7075 alloy processed via friction stir welding (FSW). FSW is known to be capable of grain refinement in the nugget zone (NZ). Two different quench media (water and air) were employed for PWHT. Regardless of the quench media, the PWHT led to the occurrence of grain growth in the NZ of the FSWed aluminum 7075 alloy. Abnormal grain growth occurred in the water quenched specimen. It is ...
Aufsatz
Cyclic Deformation Response of Ultra-fine Grained Titanium at Elevated Temperatures
(2019)
This study focuses on the high-temperature cyclic deformation response (CDR) of ultra-fine grained (UFG) titanium of commercial purity (grade 4) processed via equal channel angular extrusion as a severe plastic deformation method. Low-cycle fatigue experiments were conducted at elevated temperatures up to 600 °C and at strain amplitudes ranging from 0.2% to 0.6%. Besides temperature and strain amplitude, the influence of two processing routes (8BC and 8E) on the fatigue characteristics of UFG Ti was examined. It is ...
Aufsatz
Effect of grain size on the very high cycle fatigue behavior and notch sensitivity of titanium
(2019)
The very high-cycle fatigue performances of coarse-grained and ultrafine-grained titanium samples with different geometries at ambient temperature and various stress amplitudes were investigated. Severe plastic deformation improves monotonic strength of titanium at the cost of a loss in ductility. Ultrafine-grained titanium demonstrates a superior fatigue performance compared to that of coarse-grained counterparts in the high-cycle fatigue regime, however, suffers notch sensitivity. Furthermore, in the very high-cycle ...
Aufsatz
Parameter identification for constitutive models of innovative textile composite materials using digital image correlation
(2019-11-18)
This contribution focuses on an innovative composite material consisting of textile layers made from continuous wooden fibers embedded in a thermoplastic matrix. A finite element simulation of potential use‐cases is planned to support the development process and to study the suitability of the material in an architectural context. The simulation is based on a constitutive model assuming homogenous orthotropic elastic behavior and will be expanded to include multiscale modeling in future research. The material parameters ...