PhD defense by Anders Noel Thomsen
26.11.2020 kl. 10.00 - 13.00
Laser forming of sheet metal is an innovate method for contact-less thermal forming. The process is based on using a laser as a heat source for introducing thermal based permanent stresses and strains in the workpiece. The process has been investigated in numerous scientific articles and boasts a large potential as a non-contact free forming method. However, its use and even awareness in industry is still severely lacking.
This thesis investigates the limitations and potentials of the process, which forms the basis for introducing improvements. The investigation led to several different open problems for laser forming, which deserve further attention. However, one problem stood out as the primary driving force against the adaptation of the process; process control. Several factors constrain the use of process control. Firstly, the process is iterative, where each laser scan path introduced a small amount of the total deformation required; this creates a discrete multi-variable planning operation. Secondly, the process suffers from a relatively large degree of process variation, which when coupled with an iterative process causes variations to build up from each pass.
A framework for feedback control of laser forming was introduced and tested experimentally as part of this thesis. The framework is based on planning a part of the total process and measuring the surface. The measurements allow the framework to account for unwanted distortions and process variations. The framework shows that feedback control is possible, but further development is necessary before laser forming is competitive with traditional sheet metal forming. To improve the framework a theoretical study based on discrete constrained non-linear multi-variable optimization of the process settings using analytical equations to predict the laser forming response was performed. The study shows promise but has not been experimentally tested yet.
Associate Professor Jens Henrik Andreasen (chairman)
Department of Materials and Production, Aalborg University, Denmark
Professor Jesper Hattel
Department of Mechanical Engineering, Technical University of Denmark, Denmark
Associate Senior Lecturer.Jörg Volpp
Department of Engineering Sciences and Mathematics Luleå University of Technology, Sweden
Associate professor Benny Ørtoft Endelt
Department of Materials and Production, Aalborg University
Associate professor Morten Kristiansen, Department of Materials and Production, Aalborg University
The PhD defense will be hosted by Moderator Jens Henrik Andreasen. The lecture constitutes a 45 minutes presentation by Anders Noel Thomsen followed by a short break and a discussion session with questions from the opponents and the auditorium.
After the defense the department will host a small reception in the common room at FIB 14.
Department of Materials and Production
FIB 16, room 1.108 or Miscrosoft Teams
20.11.2020 kl. 00.00