Johannes Käsbauer, M.Sc.

Wissenschaftlicher Mitarbeiter


JournalArticle
  • Johannes Käsbauer
  • Anton Schmailzl
  • J. Prehm
  • T. Loose
  • S. Hierl
Simulation of Quasi-Simultaneous Laser Transmission Welding of Plastics: Optimization of Material Parameters in Broad Temperature Range , vol94
  • 2020

DOI: 10.1016/j.procir.2020.09.136

Thermo-mechanical simulation offers great opportunities to optimize welding processes of plastics. For realistic simulation, the temperature dependent mechanical properties need to be implemented from ambient temperature to temperatures above the flow temperature. Standard test methods are insufficient for characterization in the entire temperature range because close to the flow temperature the material is too soft for tensile tests and too stiff for rheometry. Therefore, an optimization strategy is developed, that determines unknown material parameters by testing in welding simulations. The unknown parameters are iteratively adjusted to minimize the mismatch between computed and measured set-paths. Thus, important process characteristics are calculated realistically, enabling the computer aided assessment of the weld quality.
Lecture
  • Johannes Käsbauer
  • Anton Schmailzl
  • T. Loose
  • S. Hierl
Potentials of the EFG-Method for Modeling Quasi-Simultaneous Laser Transmission Welding Considering the Melt Flow
  • 2020
Lecture
  • Johannes Käsbauer
  • Anton Schmailzl
  • T. Loose
  • S. Hierl
Thermo-Mechanical Modeling of Quasi-Simultaneous Laser Transmission Welding using LS-DYNA with Focus on Accuracy of Heat Input Calculation
  • 2020
Lecture
  • Johannes Käsbauer
  • Anton Schmailzl
  • T. Loose
  • S. Hierl
Potentials of the EFG-Method for Modeling Quasi-Simultaneous Laser Transmission Welding Considering the Melt Flow
  • 2020
JournalArticle
  • Johannes Käsbauer
  • Anton Schmailzl
  • J. Prehm
  • T. Loose
  • S. Hierl
Simulation of Quasi-Simultaneous Laser Transmission Welding of Plastics: Optimization of Material Parameters in Broad Temperature Range , vol94
  • 2020

DOI: 10.1016/j.procir.2020.09.136

Thermo-mechanical simulation offers great opportunities to optimize welding processes of plastics. For realistic simulation, the temperature dependent mechanical properties need to be implemented from ambient temperature to temperatures above the flow temperature. Standard test methods are insufficient for characterization in the entire temperature range because close to the flow temperature the material is too soft for tensile tests and too stiff for rheometry. Therefore, an optimization strategy is developed, that determines unknown material parameters by testing in welding simulations. The unknown parameters are iteratively adjusted to minimize the mismatch between computed and measured set-paths. Thus, important process characteristics are calculated realistically, enabling the computer aided assessment of the weld quality.
JournalArticle
  • Anton Schmailzl
  • Johannes Käsbauer
  • J. Martan
  • P. Honnerová
  • F. Schäfer
  • Maximilian Fichtl
  • T. Lehrer
  • L. Prušáková
  • J. Tesař
  • J. Skála
  • M. Honner
Measurement of core temperature through semi-transparent polyamide 6 using scanner-integrated pyrometer in laser welding , vol146
  • 2020

DOI: 10.1016/j.ijheatmasstransfer.2019.118814

Predicting the core temperature during welding is an ambitious aim in many research works. In this work, a 3D-scanner with integrated pyrometer is characterized and used to measure the temperature during quasi-simultaneous laser transmission welding of polyamide 6. However, due to welding in an overlap configuration, the heat radiation emitted from the joining zone of a laser transmission weld has to pass through the upper polymer, which is itself a semi-transparent emitter. Therefore, the spectral filtering of the heat radiation in the upper polymer is taken into account by calibrating the pyrometer for the measurement task. Thermal process simulations are performed to compare the temperature field with the measured temperature signal. The absorption coefficients of the polymers are measured, in order to get precise results from the computation. The temperature signals during welding are in good agreement with the computed mean temperature inside the detection spot, located in the joining area. This is also true for varying laser power, laser beam diameter and the carbon black content in the lower polymer. Both, the computed mean temperature and the temperature signal are representing the core temperature. In order to evaluate the spatial sensitivity of the measurement system, the emitted heat radiation from both polymers is calculated on basis of the computed temperature field. Hereby it is found, that more than 90 percent of the detected heat radiation comes from the joining area, which is a crucial information for contact-free temperature measurement tasks on semi-transparent polymers.
JournalArticle
  • Anton Schmailzl
  • Johannes Käsbauer
  • J. Martan
  • P. Honnerová
  • F. Schäfer
  • Maximilian Fichtl
  • T. Lehrer
  • L. Prušáková
  • J. Tesař
  • J. Skála
  • M. Honner
Measurement of core temperature through semi-transparent polyamide 6 using scanner-integrated pyrometer in laser welding , vol146
  • 2020

DOI: 10.1016/j.ijheatmasstransfer.2019.118814

Predicting the core temperature during welding is an ambitious aim in many research works. In this work, a 3D-scanner with integrated pyrometer is characterized and used to measure the temperature during quasi-simultaneous laser transmission welding of polyamide 6. However, due to welding in an overlap configuration, the heat radiation emitted from the joining zone of a laser transmission weld has to pass through the upper polymer, which is itself a semi-transparent emitter. Therefore, the spectral filtering of the heat radiation in the upper polymer is taken into account by calibrating the pyrometer for the measurement task. Thermal process simulations are performed to compare the temperature field with the measured temperature signal. The absorption coefficients of the polymers are measured, in order to get precise results from the computation. The temperature signals during welding are in good agreement with the computed mean temperature inside the detection spot, located in the joining area. This is also true for varying laser power, laser beam diameter and the carbon black content in the lower polymer. Both, the computed mean temperature and the temperature signal are representing the core temperature. In order to evaluate the spatial sensitivity of the measurement system, the emitted heat radiation from both polymers is calculated on basis of the computed temperature field. Hereby it is found, that more than 90 percent of the detected heat radiation comes from the joining area, which is a crucial information for contact-free temperature measurement tasks on semi-transparent polymers.
Lecture
  • Johannes Käsbauer
  • Anton Schmailzl
  • T. Loose
  • S. Hierl
Thermo-Mechanical Modeling of Quasi-Simultaneous Laser Transmission Welding using LS-DYNA with Focus on Accuracy of Heat Input Calculation
  • 2020
Contribution
  • Anton Schmailzl
  • S. Hüntelmann
  • T. Loose
  • Johannes Käsbauer
  • F. Maiwald
  • S. Hierl
Potentials of the ALE-Method for Modeling Plastics Welding Processes, in Particular for the Quasi-Simultaneous Laser Transmission Welding
  • 2019

DOI: 10.3217/978-3-85125-615-4-51

The Arbitrary-Lagrangian-Eulerian-Method (ALE-Method) offers the possibility to model the quasi-simultaneous laser transmission welding of plastics, in which a squeeze-flow of molten plastic occurs. It is of great interest to get a deeper understanding of the fluid-structure-interactions in the welding zone, since the occurring squeeze-flow transports heated material out of the joining zone, causing a temperature decrease inside. In addition, the numerical modelling offers the possibility to investigate the flow conditions in the joining zone. The aim of this article is to show the potentials of the ALE-Method to simulate the quasi-simultaneous laser transmission welding with the commercially available software LS-DYNA. The central challenge is to realize a bi-directional thermo-mechanically coupled simulation, which considers the comparatively high thermal expansion and calculates the interactions of solid and melted plastic correctly. Finally, the potentials of the ALE element formulations for the mathematical description of welding processes are shown, especially for those with a squeeze-flow.
JournalArticle
  • Johannes Käsbauer
  • Anton Schmailzl
  • U. Weber
  • S. Hierl
  • T. Jaus
  • M. Schwalme
Simulationsgestütze Evaluierung von Strahloszillationsmustern beim quasi-simultanen Laser-Durchstrahlschweißen.
  • 2019
Contribution
  • Anton Schmailzl
  • S. Hüntelmann
  • T. Loose
  • Johannes Käsbauer
  • F. Maiwald
  • S. Hierl
Potentials of the ALE-Method for Modeling Plastics Welding Processes, in Particular for the Quasi-Simultaneous Laser Transmission Welding
  • 2019

DOI: 10.3217/978-3-85125-615-4-51

The Arbitrary-Lagrangian-Eulerian-Method (ALE-Method) offers the possibility to model the quasi-simultaneous laser transmission welding of plastics, in which a squeeze-flow of molten plastic occurs. It is of great interest to get a deeper understanding of the fluid-structure-interactions in the welding zone, since the occurring squeeze-flow transports heated material out of the joining zone, causing a temperature decrease inside. In addition, the numerical modelling offers the possibility to investigate the flow conditions in the joining zone. The aim of this article is to show the potentials of the ALE-Method to simulate the quasi-simultaneous laser transmission welding with the commercially available software LS-DYNA. The central challenge is to realize a bi-directional thermo-mechanically coupled simulation, which considers the comparatively high thermal expansion and calculates the interactions of solid and melted plastic correctly. Finally, the potentials of the ALE element formulations for the mathematical description of welding processes are shown, especially for those with a squeeze-flow.
JournalArticle
  • Johannes Käsbauer
  • Anton Schmailzl
  • U. Weber
  • S. Hierl
  • T. Jaus
  • M. Schwalme
Simulationsgestütze Evaluierung von Strahloszillationsmustern beim quasi-simultanen Laser-Durchstrahlschweißen.
  • 2019
Contribution
  • Johannes Käsbauer
  • Anton Schmailzl
  • S. Hierl
Simulationsgestützte Prozessentwicklung beim Laser Durchstrahlschweißen von Thermoplasten ohne absorbierende Füllstoffe
  • 2018
Lecture
  • Johannes Käsbauer
Simulationsgestützte Prozessentwicklung beim Laser-Durchstrahlschweißen von Thermoplasten ohne absorbierende Füllstoffe
  • 2018
Lecture
  • Johannes Käsbauer
Simulationsgestützte Prozessentwicklung beim Laser-Durchstrahlschweißen von Thermoplasten ohne absorbierende Füllstoffe
  • 2018
Contribution
  • Johannes Käsbauer
  • Anton Schmailzl
  • S. Hierl
Simulationsgestützte Prozessentwicklung beim Laser Durchstrahlschweißen von Thermoplasten ohne absorbierende Füllstoffe
  • 2018
Contribution
  • Johannes Käsbauer
  • Anton Schmailzl
  • S. Hierl
Simulative investigation on the influence of material- and process parameter on quasi-simultaneous laser transmission welding Poster Session
  • 2017
Contribution
  • Johannes Käsbauer
  • Anton Schmailzl
  • S. Hierl
Simulative investigation on the influence of material- and process parameter on quasi-simultaneous laser transmission welding Poster Session
  • 2017