B-splines based topology optimization considering material anisotropy, overhang constraints, and build direction for additive manufacturing

This paper proposes a comprehensive topology optimization method that fully accounts for material anisotropy, overhang constraints, and build direction for the layer-by-layer additive manufacturing. An orthotropic material model is incorporated to represent the effect of build direction and scanning path upon the material anisotropy. The material density field describing the material layout is parameterized by means of B-splines to eliminate mesh dependency, while overhang constraints are formulated in terms of the density gradient to design the self-supporting structure of the obtained configuration. The influences of initial build directions upon the optimization results are studied and a setting-up strategy is developed to obtain superior designs. Finally, representative 2D and 3D examples are dealt with to demonstrate the proposed method. It is shown that superior performance is achieved by simultaneously taking into account material anisotropy, overhang constraints, and build direction in topology optimization.