Investigation on the Influence of Different Modeling of Multiple Surface Layers on a 3D Topology Optimization

Abstract

Products nowadays are expected to have load-compliant designs as well as a high degree of individuality and design flexibility. In this context, topology optimization in combination with a redesign provides a possibility to generate load-compliant product designs. In terms of achieving a high individuality and design flexibility additive manufacturing processes like selective laser melting (SLM) can be used. SLM is an additive manufacturing process that creates a part layer by layer and each one in two steps. First, the outer contour is formed and afterwards the inner area. This separation ensures that a comparatively high contour accuracy is realized. However, at the same time it results in three areas (contour, interface and hatching) with different material properties due to different cooling rates. To consider these areas including their material properties in a topology optimization, a method is developed to interrupt the topology optimization after each iteration and export the smoothed interim result. Subsequently, the exported interim result is automatically divided into the three areas by offsets using the level set method. In this contribution, a 3D topology optimization is investigated that assigns different isotropic material properties to the corresponding areas after each iteration. After this assignment, the optimization is continued and the described procedure is repeated until the optimization fulfils its convergence criterion. Thus, the influence of such an interruption and change of material properties on the result of the topology optimization is analyzed on a simple part. The results depict, that the methodology tries to maximize the surface area, if Young’s modulus of the contour area is higher in comparison to the hatching area and if Young's modulus in the interface area is lower in comparison to the hatching area. In the future, the method will be extended to include experimentally measured material properties of the SLM process.