Successfully completed doctorate
Successfully completed doctorate
On 24 November 2023, Marius Schwarz, M.Sc., received his doctorate in engineering from the Faculty of Mechanical Engineering at Chemnitz University of Technology. The examinations included the viva voce examination and a specialist presentation with defence. His dissertation is entitled „Strategies for quality assurance using optical coherence tomography in laser beam welding of thin copper and aluminium sheets“.
Dr Schwarz completed the thesis while working as a doctoral student at Mercedes-Benz AG in Untertürkheim. In organisational terms, the topic was assigned to quality assurance in the laser contacting of lithium-ion batteries. The dissertation was supervised by Professor Thomas Lampke.
The aim of this dissertation was to investigate whether a quality assurance system (OCT system) based on an optical coherence tomograph can be used to assess the welding quality during laser welding. For this purpose, thin copper and aluminium sheets were welded together in an overlap joint and a scanner-based OCT system was used with which the OCT measurement beam could be positioned autonomously locally around the processing laser beam. This allowed topological dimensional measurements to be carried out. First, a topological vapour capillary model was created for the joints under investigation in order to determine the effect of a joint gap on the welding quality and the OCT measurements. Using a developed methodology, the weld penetration depth was calculated using the capillary depth measurement of the OCT system as an example. It was possible to determine the so-called weld penetration width with the OCT system. In addition, an approach is presented with which the weld quality can be determined if a joint gap occurs. Based on the topological vapour capillary model developed, three characteristic values for evaluating the process quality are extracted from the measurement data and monitored. The methodological procedure shown can also be applied to other joints and thus extends the ability of an OCT system to determine quality beyond the exclusive monitoring of the capillary depth.
The entire WOT team congratulates you on your promotion!
Photo: The photo shows the people involved in the process (from left): Prof Jörn Ihlemann, Prof Jonas Hensel, Dr Marius Schwarz, Prof Thomas Lampke. (Photo: private)
8.1.2024 – Personnel of the professorship ( thomas.lampke@mb… )
