R. Schleich

Bio: R. Schleich is an academic researcher from University of Stuttgart. The author has contributed to research in topics: Formability & Forming processes. The author has an hindex of 4, co-authored 9 publications receiving 53 citations.

Investigation on the effect of curvature on forming limit prediction for aluminium sheet alloys

Abstract: The investigation of bendability of sheet metal alloys is of great importance for the evaluation of process robustness in production of hemmed sheet metal assemblies. Furthermore, material cracks due to bending can also occur at deep drawing operations. This contribution focuses on the experimental determination of material’s formability at deep drawing, the characterisation of bendability especially for hemming operations and the determination of formability under combined deep drawing and bending loads, respectively.

Investigation on the effect of curvature and sheet thickness on forming limit prediction for aluminium sheet metal alloys

Abstract: For characterising formability of sheet metal materials several testing methods have been developed during recent years. The most common way to estimate formability of sheet metal parts is the so called Forming Limit Diagram (FLD) method. But forming limits under bending cannot be described by the conventional FLC. This contribution reveals possibilities of an experimental characterisation of material’s bendability. Furthermore, an approach concerning the characterisation of formability under simultaneous drawing and bending for various sheet thicknesses is given.

Einfluss dehnungsabhängiger Werkstoffeigenschaften auf die Umformbarkeit von Blechwerkstoffen

Abstract: Dieser Beitrag zeigt auf Basis experimenteller Untersuchungen Einflusse dehnungsinduzierter Anderungen von Werkstoffkennwerten auf die Berechnung der Grenzformanderung und die Folgen fur sowohl ein- als auch mehrstufige Umformprozesse auf. Besonderes Augenmerk liegt dabei auf den Vorteilen dieser differenzierten Betrachtung gegenuber dem in der Praxis ublichen Stand der Technik. Effect of strain dependent material properties on formability of sheet metals This paper describes strain induced effects on the change of material properties. Because of these effects the calculation of forming limit curve changes, too. Special attention is given to the material property caused differences between one or more stepped forming operations with main advantages in comparison to the today’s common practice.

Investigation on the influence of combined shear loads on the forming limit for high strength steels

Abstract: The knowledge of material behaviour under certain load conditions, occurring in metal-forming processes, urgently calls for the development of robust production processes. For characterisation of materials behaviour in metal forming processes in the automotive industry, Forming Limit Diagrams (FLD) are mainly used to characterise formability under certain in-plane load conditions . But in industrial forming processes not only in-plane- loads, but a mixture of in-plane, bending, pure-shear and combined shear-and tensions loads can occur. But today there is a lack in testing equipment for those combined load conditions because with conventional testing set-ups no superposed shear rates can be realized. For this purpose three novel sample geometries are presented in this article. Further first experimental results show the application of the specimen geometries. On the one hand maximal achievable strains under combined shear and tension loads are measured and on the other hand a first approach to get real stress-strain curves is shown.

Neue Duktilitätskriterien für die Qualitätsbewertung von Leichtbauwerkstoffen

Abstract: KurzfassungDieser Beitrag zeigt auf der Basis bestehender Ansatze Moglichkeiten neuer Duktilitatsdefinitionen auf. Die dabei neu erstellten Ansatze bieten im besonderen Mase fur umformkritische Leichtbaublechwerkstoffe die Moglichkeit zur differenzierten Werkstoffcharakterisierung. Die Beschreibung der Duktilitat eines Werkstoffes dient nicht nur der Versagensvorhersage in der Bauteilsimulation, sondern zeigt sowohl dem Karosserieentwickler weitere Optimierungspotenziale als objektives Bewertungskriterium, als auch der Qualitatssicherung zusatzliche Prufkriterien auf.

Modeling of localization and fracture phenomena in strain and stress space for sheet metal forming

Abstract: In this study, a model based on a strain localization level to overcome the shortcomings of the well-established Forming Limit Diagram (FLD) in predicting the physical phenomenon of necking is introduced. An optical measurement system was used to capture the strain history of the Nakazima experiment until rupture occurred. In order to measure the fracture strain more accurately, a further method is introduced, which is based on the microscopic measurements of ruptured regions. This model is validated using a 3-point bending test. The results show the ability of the method to predict failure under bending conditions as well. Additionally, failure is investigated based on the pressure sensitivity and the Lode dependency. The results show that the triaxiality at the failure point is independent of the loading path.