Casting-oriented structural topology optimization with dimensional shrinkage

Solidification shrinkage and surface finishing cause the inevitable dimensional shrinkage between the blueprint and model designs, thereby creating huge cost and precision challenges to casting designs. This paper proposes an efficient structural topology optimization approach to simultaneously achieve the blueprint and model designs with uniform dimensional shrinkage in only one optimization setting. An appropriate two-projected-field scheme is established to simulate the blueprint and model designs by extending the density-based threshold projection approach. And, an effective quantitative framework is constructed to precisely predict the shrinkage rules. Besides, to ensure the castability of both the two projected designs, the Poisson equation-based constraint method is subtly integrated with the two-projected-field scheme. More importantly, to reduce the computational burden involving multiple designs and constraints, an efficient formulation is presented by reasonably considering the projected fields in the objective and constraint functions. Typical 2D and 3D numerical examples as well as one real-world example are provided to validate the effectiveness of the proposed strategies. The results show that the traditional one-projected-field scheme is difficult to yield the model design through the filtered field associated with the blueprint design. The proposed approach enables this and can help engineers achieve predictable dimensional shrinkage in an optimization way.