Alessandro Franceschi has successfully completed his PhD
On 20.12.2022, the successful disputation of our former scientific employee Alessandro Franceschi took place. His dissertation is entitled “Requirement-specific adjustment of the residual stress state in cold forging”.
His work heralds a paradigm shift regarding the residual stress state from a disturbance with potentially undesirable effects to a customised residual stress design for setting targeted product properties through specific manufacturing strategies. The aim of his work is to develop techniques and tools for the requirement-specific adjustment of residual stresses during the forming process.
The process design includes the component stress and other requirements for a desired stress state, so that the necessary process parameters are determined, which makes post-treatment in the conventional sense superfluous. Mr Franceschi divides the forward extrusion process into two sub-processes. By applying a counterforce during forward extrusion, it is possible to control the residual stresses through stress superpositions. In addition, a so-called “active die” is used, which makes it possible to adjust the die pre-stress. The developed combination of both methods extends the spectrum of achievable residual stress profiles.
Mr Franceschi's modelling uses fundamental principles of residual stress superposition in axisymmetric components to develop a strategy for the targeted introduction of residual stresses in full forward extrusion. In this way, it can be demonstrated that the setting of targeted residual stresses brings about an improvement in component properties, such as an increase in fatigue life or a reduction in component distortion. At the same time, his work provides action pointers for the creation of automatic tools for the identification of optimal process parameters, which thus result in a shortening of the conventional process chain.
The PtU thanks Mr Franceschi for his many years of commitment and wishes him all the best and much success for his professional and private future.