Optimization of Additive Manufactured Components Using Topology Optimization

Abstract

Additive manufacturing (AM) is today one of the fastest growing industries. Previously, this technology was called Rapid Prototyping. The term ‘rapid prototyping’ (RP) was used in a variety of industries to describe a process for rapidly production of parts before final release or commercialization [1]. Today, this term is not current, because now 3D printing is not used only for fabricating prototypes, but it is increasingly used for small-series production of final parts. This leads to higher requirements on sufficient strength and stiffness of these parts. This problem can be solved using advanced numerical simulations, which also allows to found appropriate solution in combination with structural optimizations. There are many types of structural optimizations (such as geometry, topography, topometry, shape or topology optimization). Topology optimization is one of the best optimizations for this purpose because it can find the best use of material within a given design space [2]. Its use is often overlooked because the final optimized shape of the part is often too complicated for conventional manufacturing technologies, but it is not for AM technologies.

The goal of the paper was to find the appropriate methodology for optimizing a part for FDM fabrication using numerical simulations and topology optimization. The first stage of the intake system of a Yamaha YZF-R6 engine for a one-seat racing car was used as a typical part (a case study) for optimization. The simulation was done with respect to temperature. The PA6 copolymer with short carbon fibres was used as the material for the printed part. Experimental tensile testing of this material at temperatures up to 160 °C according to ISO standards was done to find the mechanical parameters [3]. The transverse isotropic mechanical properties of the material with high temperature dependency were found (see Figs. 1 and 2).

The optimization was done using the NX Nastran 12 Topology Optimization solver with special manufacturing constrains for AM which allow the creation of a design with respect to minimum thickness of the walls, maximum angles for overhangs and an internal lattice structure.

The optimized structure of the part with respect to FDM AM technology and sufficient stiffness and strength of the design was found using the designed methodology. The mass of the currently manufactured aluminium alloy part was reduced by more than 68%.