SIM-AM 2023

A Combined Inherent Strain and Phase Transformation Model for the Modeling and Simulation of LPBF Additive Manufacturing Processes

  • Bartel, Thorsten (TU Dortmund)
  • Noll, Isabelle (TU Dortmund)
  • Menzel, Andreas (TU Dortmund)

Please login to view abstract download link

Additive manufacturing processes, such as Laser Powder Bed Fusion (LPBF) discussed in this paper, exhibit great potential for industrial applications in terms of optimal structures. However, in order to fully exploit this potential, one must be able to predict the process-induced distortion of the components and the occurring residual stresses and control them by adjusting the process parameters. For this purpose, computer-aided simulations with physically motivated material models are required. The metallurgical and thermal processes present in LPBF processes are numerous and complex. Therefore, models and simulations encompassing all essential aspects would have to consider multiple material scales from individual powder particles to the entire component. However, this would lead to unreasonably long calculation times. In order to obtain a satisfactory compromise between accuracy and efficiency, the decoupled multiscale approach referred to as “Inherent Strain Method” is applied which is extended by a new material model. The overall method can be briefly explained in terms of the following considered sub problems: Within the ``laser scan model'', the aforementioned newly developed and thermomechanically coupled material model based on phase transformations is employed. The goal is to determine an accurate effective heat source as a function of various process parameters such as laser speed and laser intensity. This information is then transferred to the ``layer hatch model'', where representative transformation strains or, in other words, inherent strains are calculated using a simplified version of the previously mentioned material model. Finally, these inherent strains are prescribed as the load in a purely mechanical simulation of the manufacturing process of the final part in the ``part model''. The capabilities of the present framework are explored through simulations of the behavior of a twin cantilever beam, where the effects of various process parameters on the overall material and structural behavior are investigated.