Abstract. Additive manufacturing (AM) is a very promising technology; however, there are a number of open issues related to the different AM processes. The literature on modelling the existing AM processes is reviewed and classified. A categorization of the different AM processes in process groups, according to the process mechanism, has been conducted and the most important issues are stated. Suggestions are made as to which approach is more appropriate according to the key performance indicator desired to be modelled and a discussion is included as to the way that future modelling work can better contribute to improving today's AM process understanding.
The interest in additive manufacturing (AM) of cement-based materials is steadily increasing. Moreover, there is a growing need for higher productivity and part quality. In this study, the impact of the different values of the process parameters on part quality was identified. An alternative process-control strategy was investigated, according to which the width of the extruded path is controlled by the ratio of the extrusion speed over the scanner head speed. To conduct linear-and rotational-extrusion experiments, an experimental apparatus was designed. The significance of the effect of the speed ratio on the part quality was found to be the highest, followed by the extrusion radius, whereas the extrusion speed appeared to be of low importance. Therefore, in linear extrusion, high quality and consistency can be achieved by maintaining the ratio value above 0.8. However, in rotational extrusion, the effect of the radius was additionally considered by calculating the ratio on the outer side of the part, rather than on the centerline. Thus, acceptable quality and consistency were ensured for both linear and curved paths by controlling the aforementioned ratio values.
An important quality-related aspect of metal-based additive manufacturing (AM) parts is the existence of thermal stresses and deformations. To address this issue, a 3D thermal simulation approach for powder bed fusion (PBF) processes has been developed, along with the definition of an index that encapsulates the intensity of the non-uniformity of the thermal field. The proposed approach delivers sufficient and computationally low-cost results regarding the intensity of the expected thermal stresses and deformations. A case study of eighteen parts is presented, in which eight different scanning strategies are tested to identify the optimum scanning strategy in terms of thermal stresses and deformations. Finally, the impact of different design elements on the importance of the scanning strategy selection in terms of thermal stresses and deformations is discussed. Both the developed model and the index have been benchmarked using experimental and computational data.
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