An Adaptive Material Mask Overlay Method: Modifications and Investigations on Binary, Well Connected Robust Compliant Continua

The material mask overlay strategy employs negative masks to create material voids within the design region to synthesize perfectly binary (0-1), well connected continua. Previous implementations use either a constant number of circular masks or increase the latter via a sequence of subsearches making the procedure computationally expensive. Here, a modified algorithm is presented wherein the number of masks is adaptively varied within a single search, in addition to their positions and sizes, thereby generating material voids, both efficiently and effectively. A stochastic, mutation-only search with different mutation strategies is employed. The honeycomb parameterization naturally eliminates all subregion connectivity anomalies without requiring additional suppression methods. Boundary smoothening as a new preprocessing step further facilitates accurate evaluations of intermediate and final designs with moderated notches. Thus, both material and contour boundary interpretation steps, that can alter the synthesized solutions, are avoided during postprocessing. Various features, e.g., (i) effective use of the negative masks, (ii) convergence, (iii) mesh dependency, (iv) solution dependence on the reaction force, and (v) parallel search are investigated through the synthesis of small deformation fully compliant mechanisms that are designed to be robust under the specified loads. The proposed topology search algorithm shows promise for design of single-material large deformation continua as well.