Modelling and Simulation

The Fraunhofer Institute for Laser Technology ILT engages in fundamental work on the description of technical processes as well as their monitoring, control and regulation. With the combination of a deep physical understanding of laser processes and modern computational engineering techniques, Fraunhofer ILT provides the basis for tailor-made laser processing.

Our core competences include the modelling of radiation sources – in particular, high-power lasers and gas discharges – as well as their application in manufacturing technology. The involved physical processes range from generation, propagation and absorption of radiation to transport processes and phase transformations induced in the material by radiation. We apply methods of computer engineering to analyse the measurement data and to monitor the processes. These include, in particular, numerical methods for simulation and visualization of the processes as well as algorithms for interpretation of measurement data. 

Our experienced team includes researchers in the areas of applied mathematics, physics and computer engineering. Together, we offer our customers model-based solutions for technical tasks. We develop and analyse individual approaches based on the knowledge of our customers and our expertise as well as the properties of existing models.

• Design of resonators for gas, solid and high-power diode lasers
• Optimization of the beam guidance in optical systems
• Radiation propagation in gas and vapor
• Subsonic and supersonic fl ows in liquid, gas and vapor
• Mass flow and heat transfer
• Dynamic simulation for ablating, cutting, patterning, additive manufacturing and drilling
• Digitalization concepts in computational physics
• Modular dynamics of ultrashort pulse processing
• Simulation of laser processing in photovoltaics
• Control of manufacturing processes
• Algorithms for analysis of measurement data
• Programming of graphical user interfaces for simulation and visualization
• Numerical methods and calculation approaches, such as Cluster-In-Cell (CIC), Finite Element (FE), Finite Volume (FV), Discontinuous Galerkin (DG) and model reduction methods in time-variant domains
• Meta-modelling of physical phenomena and manufacturing processes

In order to share our knowledge with customers, we offer a »Simulation as a Service« platform named »SimWeb«. The platform provides our highly individual simulation and analysis tools without a time-consuming installation process also on mobile devices. 

High power ultrashort pulsed lasers enable high precision ablation of a multitude of materials resulting in unprecedented manufacturing possibilities. In order to bring this precision into a larger build volume, our team investigates processing strategies based on a deep understanding of the underlying physics. Using a multi-scale approach, which takes our knowledge about single pulse laser ablation and maps it to a multi-beam matrix, to predict distortions and to optimize process parameters facilitates the patterning of thin films used in the production of e. g. water fi lters.

Additive manufacturing is a game changer in production technologies. However, the layer-by-layer construction of geometries is still an erroneous task and many prototypes have to be discarded due to unforeseen defects. For this reason we develop »StrucSol«. A thermo-mechanical simulation which allows the analysis of tracks, hatches, layers, up to an entire part. In the future, »StrucSol« will enable manufacturers to select scan strategies, which fulfi ll the requirements for e. g. deformations and residual stresses within the component and thus pave the way towards a ‘first-time-right‘ approach for components in additive manufacturing.

The model creation and simulation for drilling with lasers are directed primarily at avoiding recast on the drill hole wall for a long pulse length (microseconds) and at increasing the drilling speed for a smaller pulse length (sub-picoseconds to nanoseconds). Through analysis of drilling with long pulse length, we can identify four different phenomena that interact dynamically to cause the formation of recast on the drill hole wall. In the analysis of drilling with short and ultrashort pulse lengths and higher laser beam intensity, we also take into consideration the inertia of the melt, recondensation of the vapour on the hole wall, refl ection of the beam and changing of the state equation upon nearing the critical temperature. This knowledge was successfully used to improve e. g. processes for the production of cooling ducts in turbine components. By the customer simulation tool »AsymptoticDRILL« the asymptotic shape of the bore can be described when drilling metallic materials with long-pulsed laser radiation.

The combination of diagnostics and simulation yields a systematic defi nition of the relationships between cut quality and cutting parameters. Through analysis of the cut quality, we can identify at least three different types of ripples and four different types of adherent dross. The formation of the various score mark and burr types can be described by a straightforward set of parameters as well as their dynamic interactions during cutting. Our vision of a cognitive cutting machine comprises intelligent confi guration and systematic error diagnosis. With the cognitive cutting machine, we advance developments in cutting processes to the physical limits of the laser beam, machine and process, with a defi ned level of quality.