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TY - THES AU - Stebner, Sophie Charlotte TI - Development of a soft sensor system for the property-controlled process design of freeform bending with moveable die PB - Rheinisch-Westfälische Technische Hochschule Aachen VL - Dissertation CY - Aachen M1 - RWTH-2024-09686 SP - 1 Online-Ressource : Illustrationen PY - 2024 N1 - Veröffentlicht auf dem Publikationsserver der RWTH Aachen University N1 - Dissertation, Rheinisch-Westfälische Technische Hochschule Aachen, 2024 AB - The freeform bending process with movable die is an innovative bending process that allows the manufacture of complex three-dimensional geometries without a change in the bending tool. Thus, it offers a high degree of design freedom and customization. The initial situation of this scientific work was the ability of bending complex geometries, however without any knowledge on relevant mechanical properties, that were set in the bent component. This led to high amounts of scrap material, time consuming adjustment procedures during the process as well as unknown reliability regarding the component’s performance. Hence, there is a need to implement a closed-loop property-control into the freeform bending process, that can adjust the degrees of freedom on offer during the bending procedure according to the needed mechanical properties of the tube. Mechanical properties that are especially of interest for bent round tubes are the strength, ductility as well as the residual stresses in axial and hoop direction, as they predominantly determine the components application. However, these mechanical properties are time-consuming or even impossible to determine during the bending process, where it is necessary to know them, in order to be able to manipulate the actuators according to the needed properties. Hence, there needs to be a fast, reliable and efficient solution for the derivation of the strength, ductility and residual stresses in the tubes. Thus, the focus of this work lies on the conception of a so-called soft sensor based on state-space models that can quickly derive the relevant mechanical properties during the bending process. The soft sensor relies on Ultrasonic Contact Impedance hardness and Barkhausen Noise measurements that are susceptible to a change in macroscopical/microscopical properties in the investigated material and can, furthermore, be implemented into the bending machine. Strength, ductility, hoop, and residual axial stress measurements are taken partly experimentally as well as numerically and are correlated to the Ultrasonic Contact Impedance hardness and Barkhausen Noise respectively such that a fast and reliable derivation of the relevant mechanical properties is enabled. Hence, this work lies the foundation for a closed-loop property-control of the bending process in introducing a methodology for the quick and reliable determination of immeasurable parameters in a component allowing a more resource and economically efficient design of the process. LB - PUB:(DE-HGF)11 DO - DOI:10.18154/RWTH-2024-09686 UR - https://publications.rwth-aachen.de/record/995044 ER -