Maschinenbau und Werkstofftechnik
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Adaptives Spiegelelement
(2021)
Forming complex parts out of high and ultra-high strength aluminium alloys has proved to be more challenging in comparison to the currently used deep drawing steels. Nevertheless, aluminium alloys show a limited formability in contrast with, for example, deep drawing steels. Novel processes like Warm-forming, W-Temper or Hotforming, offer the potential to produce light and highly integrated one-piece components from such aluminium alloys at elevated temperatures. When considering aluminium alloys of the 7000 group, which can reach strength values (UTS) of about 600 MPa, crash components such as side impact bars would offer a suitable field of application.
Forming at elevated temperatures, in particular with the Hotforming process, offers high potential in the production of complex structural components on the one hand and in the use of existing press hardening equipment on the other. To date, the material behaviour of aluminium alloys in the 7000 group, applied in such processes and in the later final state after forming, is not sufficiently known.
Therefore, in this study, systematic investigations on the formability and the final strength during and after forming at elevated temperature of the EN AW-7075 aluminium wrought alloy from different suppliers are conducted. In general, material- and damage/ failure models were created and implemented into simulation in order to make predictions. Characterisation of the plastic material properties on the basis of various tensile specimens as shear-, notched-, tensile- and Erichsen tests are carried out to adapt the complex material- and failure models such as Barlat YLD2000 and GISSMO to the experimental values using a parameter optimisation. These were made for the material conditions during forming, i.e. after solution heat treatment, the final condition after artificial ageing at 180°C for 20 minutes, which corresponds to the cathodic dip coating, and the T6 condition, which is the highest strength condition.
To evaluate a suitable friction coefficient for high temperature forming processes, anti-friction agents are screened, and the potential applicability evaluated by strip-drawing tests. Thereby, using an analytical relationship, friction coefficients are determined at room temperature and 180°C, which are used as corresponding friction model for the finite element forming simulation.
Crash simulations using the nonlinear finite element method (FEM) of side impact protection beams are used to demonstrate the weight saving potential of high and ultra-high strength aluminium alloys compared to a beam made of press hardened steel. A weight saving of about 20 % could be achieved with the same crash performance. This can be significantly increased to around 30 % - 40 % by using local reinforcements such as CFRP or GFRP (carbon/ glass fibre reinforced plastic) patch. For this reason, a novel process was developed which is based on the conventional Hotforming process with an integrated thermal direct joining step called “Extended Hotforming”.
Subsequently, a heatable forming tool for the production of a serial like sheet metal side impact beam was developed to validate the finite element simulation and to demonstrate the potential of the forming processes at elevated temperatures for aluminium sheet metal components.
An Investigation of the Deep Drawing Behavior of Automotive Aluminum Alloys at Very Low Temperatures
(2020)
Besonderheiten der Didaktik der Service-Mathematik innerhalb der Didaktik der Hochschulmathematik
(2020)
Besonderheiten der Didaktik der Service-Mathematik innerhalb der Didaktik der Hochschulmathematik
(2019)
Die Begriffe künstliche Intelligenz und digitaler Zwilling sind prägende Themen der heutigen Zeit. Zwar beeinflussen beide Themen die Entwicklung der Gesellschaft auf verschiedene Arten und Weisen. Dennoch sind sie als Untersuchungsobjekt schlecht definiert und es herrschen etliche unterschiedliche Verständnisse dieser Begriffe.
Der vorliegende Aufsatz nähert sich dem Begriffen künstliche Intelligenz und digitaler Zwilling durch eine Literaturanalyse, um das Verständnis dieser Begriffe in ihrer Nutzung zu schärfen. Im Anschluss der Begriffsbetrachtung wird für jeden der zwei Begriffe betriebliche Anwendungsbereiche aufgezeigt. Folgend den Einzelbetrachtungen werden mögliche Forschungsrichtungen aufgezeigt und diskutiert.
Biomechanischer Pedelec-Prüfstand zur besseren Verifizierung der Lebensdauer von Pedelec-Getrieben
(2020)
Biomechanischer Pedelec-Prüfstand zur besseren Verifizierung der Lebensdauer von Pedelec-Getrieben
(2020)
Black box efficiency modelling of an electric drive unit utilizing methods of maschine learning
(2021)
The surface topography of biodegradable polymer foils is modified by mechanical imprinting on a submillimeter length scale. The created patterns strongly influence the wetting behavior and allow the preparation of hydrophobic surfaces with controlled solid-liquid interaction. A detailed analysis of anisotropic surface patterns reveals that the observed effect arises from a combination of topographical and compositional changes that are introduced to the surface. As a main result it is found that an individual combination of material and structure is required for the production of water-repellent biopolymer foils that are highly attractive for packaging applications.