Length scale control schemes for bi‐directional evolutionary structural optimization method

This work develops length scale control schemes for bi‐directional evolutionary structural optimization method, enabling an enhanced and flexible control of the method on structural member sizes. Specifically, the maximum length scale control is achieved by constraining local material volumes below a threshold value, which is determined upon the allowed maximum length. The massive per‐element volume constraints are aggregated by the p‐norm global measure. The aggregated volume constraint is augmented to the conventional compliance design objective through a Lagrange multiplier. On the other hand, the minimum length scale control is achieved by a post‐processing modification of local feature according to the skeleton detected from a preliminarily optimized topology. The sensitivity numbers of the local structural features that violate the minimum length scale constraint are compensated during the post‐processing modification. Both 2D and 3D benchmark design results show that the proposed schemes are effective and efficient in controlling both the maximum and minimum structural length scales.