Concurrent optimization of building direction and structural topology for multi-axis additive manufacturing of rotary parts considering anisotropic strength

Abstract

The additional printing degrees of freedom in multi-axis additive manufacturing (AM) based on the BC table machine facilitate control of the building direction (BD), the formation of complex curved surfaces, and the fabrication of rotary parts. This provides significant advantages in controlling material anisotropy and structural layouts. In topology optimization (TO), concurrent optimization of BD and topological layouts can fully take advantage of the process-induced anisotropy. However, most of the previous studies were limited to three-axis AM systems and failed to fully exploit the manufacturing potential of multi-axis AM machines. Therefore, this study develops a TO method tailored for multi-axis AM based on the BC table machine. Firstly, an innovative constitutive model is developed for printing rotary parts based on the BC table machine. This model describes the constitutive characteristics of anisotropic rotary parts formed by $C$-axis rotation after adjusting the print platform based on the $B$-axis to a non-horizontal plane, providing a theoretical foundation for material property interpolation and BD optimization. Secondly, the Tsai–Hill failure criterion for multi-axis AM of rotary parts is derived, which can predict the anisotropic strength distribution under different BDs. Next, a TO model is developed to concurrently optimize BD and topological layouts considering anisotropic strength and structural stiffness in multi-axis AM, and the sensitivities of the objective function and constraints are derived. Finally, optimization examples of hook supports and compressor disks are presented to validate the importance and effectiveness of BD optimization and anisotropic strength constraints, while an optimization example of turbine rear cooling plates demonstrates the method’s engineering applicability. The results show that this method can concurrently optimize the BD and structural layout of multi-axis AM of rotary parts, fully utilizing anisotropy in AM and improving overall structural performance.