A Coupled Discrete Element and Incompressible Smoothed Particle Hydrodynamics Approach to Efficiently Simulate Laser Metal Deposition Processes

  • Weißenfels, Christian (University of Augsburg)
  • Tang, Xiaofei (Leibniz University Hannover)
  • Wriggers, Peter (Leibniz University Hannover)

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Among the numerous 3D printing techniques in the context of Additive Manufacturing of metals, the Laser Metal Deposition (LMD) process offers the possibility of near-net-shape fabrication. Here, the powder or wire feed is directly integrated into the laser and the material is only melted at the deposited location. This technique allows higher process speeds, higher build rates and simplifies the change of materials during printing. In addition, products with very large build volumes can be manufactured [1]. On the other hand, a precise adjustment of the process parameters is required. Numerical simulations enable a virtual design. In addition, correlations between process, structure and properties can be uncovered and 3D printing technologies can be optimally designed. The prerequisite for this is the accurate virtual reproduction of the individual physical processes during printing [2]. To enable an efficient virtual reproduction of the LMD process, the Discrete Element Method (DEM) is coupled with Incompressible Smoothed Particle Hydrodynamics (ISPH). Therein, the powder is considered as a rigid body during feeding. Upon contact with the laser the individual particles are then discretized using ISPH. The major challenge in meshfree particle methods is the fulfilment of the essential requirements so that an accurate approximation of the true solution can be guaranteed [3]. Therefore, a modification of the ISPH algorithm is proposed to improve the quality of the approximation. In the virtual reproduction, all the main physical effects, such as surface tension, wetting, Marangoni convection and recoil pressure, are considered. The interaction between the individual phases is modeled as a contact formulation. Numerous examples, including comparisons with experimental results, demonstrate the quality of the proposed approach for efficient modeling of the Laser Metal Deposition process.