PhD defence of Nagasai Meghana Kauta

Analysis and modelling of flowformability through a hybrid experimental-numerical approach

Nagasai Meghana Kauta conducted her doctoral research under the supervision of Pierre-Olivier Bouchard, Katia Mocellin and Elisabeth Massoni, CSM team. She will defend her PhD in Computational Mechanics and Materials on October 11th, 2024 in front of the following jury:

Abstract:

To address the challenge of damage prediction in industrial flowforming processes, the current PhD is dedicated to the numerical modelling of conical and tube flowforming processes using Forge® software. In particular, an innovative methodology to characterise damage by means of design, testing and modelling of a novel conical flowformability test is implemented. Alongside, Johnson-Cook law, a thermo-mechanical material behaviour model, is identified by inverse analysis, based on simple compression tests performed with strain rate and temperature sensitivity. Considering the complex loading paths observed during flowforming, damage characterisation is performed by means of a hybrid experimental-simulation methodology based on the flowformability tests. Depending on the dominant stress states, two Damage Fracture Criteria (DFCs) – normalised Cockcroft-Latham and Maximum Shear Stress criteria – are identified. During the flowforming process simulations, damage is predicted satisfactorily, with the demonstration of two different damage mechanisms on either side of the flowformed part surface.

Keywords: Flow Forming, Material Behaviour Law, Flowformability, High Strain Rates, Finite Element Modelling, Uncoupled Damage Laws