Investigation of heat source modeling for selective laser melting

Selective Laser Melting (SLM) is an emerging Additive Manufacturing technology for metals. Complex three dimensional parts can be generated from a powder bed by locally melting the desired portions layer by layer. The necessary heat is provided by a laser. The laser–matter interaction is a crucial physical phenomenon in the SLM process. Various modeling approaches with different degrees of complexity exist in the literature to represent the laser–matter interaction within a numerical framework. Often, the laser energy is simply distributed into a specified volume. A more precise approach is ray tracing. The laser beam can be divided into moving discrete energy portions (rays) that are traced in space and time. In order to compute the reflection and absorption usually a triangulation of the free surface is conducted. Within meshfree methods, this is a very expensive operation. In this work, a computationally efficient algorithm is developed which avoids triangulation and can easily be combined with meshfree methods. Here, the suggested ray tracing algorithm is exemplary coupled with the stabilized Optimal Transportation Meshfree Method. The importance of ray tracing is evaluated by simulating the fusion of metal powder particles. A comparison of the results with a volumetric heat source approach shows that ray tracing significantly improves the accuracy of absorption and vaporization.