Simulation based process analysis of the powder bed additive manufacturing process Selective Laser Melting (SLM)

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Laser based Additive Manufacturing technologies such as powder bed based selective laser melting allow an almost unlimited geometrical freedom in the production of metallic functional parts. Due to existing process deficits like residual stresses and part distortion this immense potential for the production of functional parts of high complexity can be exploited in a limited way only. This is caused by the currently insufficient understanding of the involved physical processes both locally in the interaction or process zone (e.g. beam propagation in the powder layer, evaporation) and globally in the part (thermomechanics). Neither part nor specific to material there are currently concrete recommendation regarding a stress or distortion minimizing process management. The scientific benefits of the project is given by the development of a multiscale simulation of the SLM process, which reduces the computation time for a thermomechanical simulation by using multiscale methods and parallelized algorithms. By the computational prediction of distortion and residual stresses a gained understanding of the process will help to identify process strategies for stress and distortion-minimizing production. The aim of this project is to reduce the number of degrees of freedom (factor 1,000-10,000) required for simulations of parts by means of multiscale approaches, thus realizing a macro-simulation of the process in which the welding sequence, the supporting structures and process parameters are taken into account. Further development of an existing model for the process zone (meso-scale) which allows a sufficiently accurate calculation of the temperature fields in acceptable computation times (<1h) is necessary for the construction of the multiscale simulation. The calculated temperature-time cycles are the input for a multiscale simulation for the thermomechanical processes of parts. Based on the gained understanding of the process the relevant process variables will be identified and experimental process strategies for stress and distortion-minimizing production will be developed and validated using relevant parts.