Combined optimization of part topology, support structure layout and build orientation for additive manufacturing

Matthijs Langelaar

doi:10.1007/s00158-017-1877-z

Matthijs Langelaar

Open Access

https://doi.org/10.1007/s00158-017-1877-z

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Abstract

Additive manufacturing (AM) enables the fabrication of parts of unprecedented complexity. Dedicated topology optimization approaches, that account for specific AM restrictions, are instrumental in fully exploiting this capability. In popular powder-bed-based AM processes, the critical overhang angle of downward facing surfaces limits printability of parts. This can be addressed by changing build orientation, part adaptation, or addition of sacrificial support structures. Thus far, each of these measures have been studied separately and applied sequentially, which leads to suboptimal solutions or excessive computation cost. This paper presents and studies, based on 2D test problems, an approach enabling simultaneous optimization of part geometry, support layout and build orientation. This allows designers to find a rational tradeoff between manufacturing cost and part performance. The relative computational cost of the approach is modest, and in numerical tests it consistently obtains high quality solutions.

Highlights

Additive manufacturing (AM) offers unprecedented form freedom and is rapidly being adopted throughout industry
This approach builds on the simplified AM process simulation we proposed to determine the printable regions of a part, which will be referred to as ‘AM filter’ (Langelaar 2016b, 2017)
To consider other critical angles, element aspect ratios had to be modified. Both in critical angle and in printing direction, we propose to separate the discretizations used in the finite element (FE) analysis and the simplified process simulation performed by the AM filter

Summary

Introduction

Additive manufacturing (AM) offers unprecedented form freedom and is rapidly being adopted throughout industry. To fully exploit the potential offered by AM technologies, freeform design optimization and in particular topology optimization (TO) is recognized to be of key importance (Brackett et al 2011; Rosen 2014). Conventional TO does not account for specific AM restrictions, which can affect the optimal design layout significantly. Beyond a critical overhang angle, structures cannot be printed with the desired quality. In particular for popular powder-bed metal AM processes (e.g. selective laser melting, SLM) this forms an important restriction with implications for design. Other relevant considerations are e.g. local overheating, part distortion and even part failure during the printing process. These aspects require computationally intensive process simulations and are outside the scope of the present study

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