Project Details
Projekt
Defined inducement of residual stresses via suitable forming operations in order to create bi-stable, metallic tube profiles with a full circle cross section
Applicant
Professor Dr.-Ing. Gerhard Hirt
Subject Area
Primary Shaping and Reshaping Technology, Additive Manufacturing
Term
from 2017 to 2024
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 374688658
The overall goal of this research project is the production of bistable, metallic, fully-closed tube profiles. Bistability in this case refers to the existence of two stable geometries, a tube profile as well as a geometry used for transportation. A change between these two stable states is possible employing elastic strains only. In case of metals, bistability is enabled due to residual stresses introduced to the material by inhomogeneous forming processes. Within the first funding period of the addressed priority program SPP 2013 a bistable tube profile with an additional transportation geometry has been manufactured successfully combining two bending operations. In order to design the bending processes, both an FE model as well as a semi-analytical model have been developed. Both models can predict bistability and the resulting profile geometry based on the bending radii. Due to fast calculation, the semi-analytical model enables a detailed process layout for the production of bistable tube profiles.Based on these models, a concept for the continuous production of large bistable tube profiles has been developed in the second phase. Therefore, an incremental bending process introducing stresses activating the transportation geometry is combined with roll profiling, which aims on stresses triggering the tube profile shape.Based on the results of the first two funding phases, the following sub-goals will be addressed in the third funding phase, which are reflected accordingly in the work program: (1) optimization and extension of the process chain consisting of incremental die bending and roll forming for the production of long bistable tubes, (2) creation of prognosis models for the operation of the components, (3) verification of residual stress stability and component properties under given application boundary conditions.At the end of the third funding period, an industrializable continuous process chain for the production of large-area bistable components will thus be available. With the aid of the prediction models, application scenarios can be evaluated and the residual stress and property stability of the new products can be measured by means of experiments. New bistable products can thus be fully evaluated and manufactured by introducing residual stresses.
DFG Programme
Priority Programmes
Co-Investigator
Dr.-Ing. Marco Teller
