Simultaneous Topology and Build Orientation Optimization for Minimization of Additive Manufacturing Cost and Time
The ever-present demand for increased performance in mechanical systems, with reduced cost and manufacturing time, has led to the adoption of computational design tools and innovative manufacturing methods. Among these tools is topology optimization, which typically produces highly complex designs that can be prohibitively difficult to manufacture. However, recent developments in additive manufacturing provide the means to manufacture such designs, including components suitable for service in industrial and commercial applications. Integration of these two technologies has the potential to reveal further benefits and innovate the design and manufacture of mechanical components. This work presents a novel mathematical methodology for simultaneous build orientation and topology optimization, which considers additive manufacturing cost and time, and structural compliance. Various physical factors that influence additive manufacturing cost and time were researched, with component surface area and support volume implemented as contributors in this work. The presented methodology approximates support volume throughout topology optimization with variable build orientation; a critical ability, as support volume is highly dependent on both part topology and build orientation. This enables direct minimization of support volume in simultaneous density-based topology and build orientation optimization; an area that was previously unaddressed in literature. Sensitivity expressions were derived for the continuous and differentiable methodology, thereby permitting the use of efficient gradient-based optimization solvers. Three numerical examples are provided that demonstrate the proposed methodology is capable of efficiently identifying optimum build orientations, while performing the simultaneous optimization. Evaluation of the support volume and build time required to manufacture the optimization results, using commercial additive manufacturing software, demonstrated the ability of the optimization to reduce additive manufacturing cost and time. The simultaneous optimization performed in these examples produced a range of designs with equivalent performance to designs produced by multi-objective topology optimization performed at a fixed optimal orientation.