A Methodical approach for additively manufactured heat-generating structures – linkage between material development, manufacturing process and geometry

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Additive Manufacturing like Material Extrusion (MEX), offers new freedom in design, due to its principle of layer-by-layer material deposition. Among other benefits, this allows a combination of multiple materials within one part, without additional assembly and joining processes are needed. Thus, an integration of material-specific functions as electrical conductivity for heat generation is enabled which provides a very efficient exploitation of high-cost functional polymers.The integration of heat-generating structures allows manufacturing individualized Joule heating systems (geometry and surface temperature) or actuators by using thermally activated shape-memory polymers. Two central challenges currently limit the exploitation of such potentials. One is the very limited performance of functional composites in terms of electrical conductivity accompanied by an extremely high viscosity at process temperature. The other challenge is the lacking in-depth knowledge about the inherent dependencies between the choice of process parameters and geometry and the resulting electrical part properties. This is due to a change in the material properties caused by anisotropies that originates from the manufacturing process. From this follows, that a systematic design of additively manufactured structures for heat generation with respect to aspects regarding material development, manufacturing process and geometry is strongly limited at present.This research project aims to develop a methodological approach for the design of additively manufactured heat-generating structures. The closely linked cooperation between the fields of process engineering and engineering design is the prerequisite for elucidating the complex interactions of the material system, process parameters and the design of geometry. This includes investigating the production process of functional polymers with defined electrical and process-relevant properties for MEX, as well as process and geometry related levers for reaching defined surface temperatures. By means of strand-level resolved thermographic analysis, the effect of all influencing factors is assessed and regarded for the provision of design-knowledge. The clarified dependencies between material properties, manufacturing process and geometry definition will be employed to establish a model, which is physically based to the greatest extend. It is also applied to parameterize a numerical model by means of the Finite Element Method (FEM). The evaluation of the methodological approach and the FEM-Model will be done by the targeted design and manufacturing of integrated heat-generating structures with preliminarily defined properties (surface temperature and geometry).