Structural topology optimization considering casting and stress constraints under uniform dimensional shrinkage

This work proposes and investigates a new multi-field-multi-constraint coupled topology optimization problem, in which stress control, design castability, and geometry dimensional shrinkage issues that are of concern to practical engineering are simultaneously considered. In the optimization proposal considered, a pair of special twin designs are generated using a two-projected-field scheme, which maintains a consistent topological configuration and uniform dimensional shrinkage variations during the optimization process. The implicit correlation between these twin designs poses major challenges to their independent stress and castability control. To this end, an appropriate formulation is presented by reasonably integrating stress and casting constraints into the optimization proposal with dimensional shrinkage. And, special numerical techniques including stress penalization, aggregation approximation, approximation correction, and regional regularization are appropriately introduced to construct an effective solution strategy. Typical numerical examples are operated to demonstrate the validity of the proposed method and systematically evaluate its numerical properties. The results indicate that in the absence of necessary stress control measures, the obtained twin designs cannot avoid local high-stress concentration under uniform dimensional shrinkage. In contrast, the proposed method can effectively address this issue, but at the cost of the design stiffness under a given material volume limit. As a result, twin designs used for blueprint and model designs that simultaneously meet stress, castability, and uniform dimensional shrinkage requirements are now readily available.