Stress-based shape and topology optimization with cellular level set in B-splines

A parametric level set approach based on B-splines is developed for the stress-based shape and topology optimization of cellular structures. In this method, the whole design domain is divided into a set of non-overlapping sub-domains, within each of which the structure is represented by an implicit B-spline level set function. This parameterization scheme ensures that the adjacent cells can be smoothly connected. The stress value of the structure is computed by using ap-norm function-based aggregation. The extended finite element method is implemented to calculate the structural stress. Moreover, a new optimization strategy based on a two-field formulation is proposed to eliminate numerical instability in the optimization process. A continuity scheme based on the least square method is proposed to guarantee the high-order connectivity at the adjacent cell boundary. In addition, optimized cellular structures with different cell partitions are obtained and discussed. Several numerical examples are presented to illustrate the applicability of the approach.