(429f) Realistic Thermal Sensor Modeling Using Finite Element Method (FEM) of Direct Metal Laser Solidification (DMLS)

In the additive manufacturing (AM) industry, the direct metal laser solidification (DMLS) process has received significant research interest because of its ultra-high precision and geometry variability [1]. However, because of the thermal and mechanical complexity, process failures are often encountered in DMLS, which maybe lead to part defects or even detrimental damage to the printing platform. These heating abnormalities may lead to thermal and mechanical stresses on the build part and eventually may cause physical problems like keyholing or lack of fusion [2]. As a result, crucial problems like recoater jam may be induced by the undesired part extrusion above the powder surface [3]. To visualize what is happening during the printing process and, in-situ sensors are developed to investigate and record the printing process information [4].

Thus, to facilitate engineers to understand the abnormality and the underlying physics of the complicated monitoring output, a large-scale finite element method (FEM) model is developed to investigate the heat transfer behavior of the DMLS process and extract experimentally relevant thermal features. Specifically, a microscopic and a meso-level sub-model are initially developed to describe powder properties and the laser behaviors, respectively, and their outputs are directly incorporated in the experimental-scale FEM model. The FEM model-generated data are then processed to reproduce the long-wave infrared camera (LWIR) sensor outputs to relate the physical defects and the output thermal images.

[1] Liu, R., Wang, Z., Sparks, T., Liou, F., Newkirk, J., 2017. Aerospace applications of laser additive manufacturing, in: Laser Additive Manufacturing. Elsevier, pp. 351–371.

[2] Grünberger, T., Domröse, R., 2014. Optical in-process monitoring of direct metal laser sintering (DMLS): A revolutionary technology meets automated quality inspection. Laser Technik Journal11, 40–42.

[3] Gong, H., Rafi, K., Gu, H., Starr, T., Stucker, B., 2014. Analysis of defect generation in Ti–6Al–4Vparts made using powder bed fusion additive manufacturing processes. Additive Manufacturing1, 87–98.

[4] Scott, C.,2017.EOS introduces EOSTATE Exposure OT, First Commercial Optical Tomography System for Additive Manufacturing. https://3dprint.com/178624/eos-eostate-exposure-ot/(Accessed on 2020-07-19).