Extension of a Simulation Model of the Freeform Bending Process as Part of a Soft Sensor for a Property Control

This work introduces an Abaqus CAE simulation model and its validation for freeform bending with movable die, which is extended in the simulation of a weld seam for the longitudinally welded tube. The superordinate goal is the development of a soft sensor, that can derive mechanical properties of a freeform bent tube as a basis for a closed-loop control. To guarantee a close monitoring of the mechanical properties, the soft sensor needs to be able to extrapolate the mechanical properties spatially. Because the investigated steel tubes are longitudinally welded, the weld depicts a disturbance regarding the rotational symmetry. In developing and validating a numerical simulation of the process, that quantitatively describes the influences the weld has on the mechanical properties, a significant improvement of the qualitative and quantitative prediction of the soft sensor can be achieved. The numerical modelling is done based on tensile tests on material taken from the weld seam, where hardness measurements are then used for the local validation of the model. The validated model now provides a time as well as cost efficient way of a primary investigation of the mechanical properties, especially regarding the local strength of the steel tube for a soft sensor and as input data for a feed forward control in the machine. Therefore, this work represents an important addition to the superordinate goal of developing a closed-loop property-control based on a soft sensor for freeform bending with movable die.