A geometry constraint handling technique for stiffener layout optimization problem

Beam stiffeners have frequently been used for raising natural frequencies of base structures. In stiffener layout optimization problems, most of the previous researches considering the position and/or the length of the stiffener as design variables dealt with structures having just simple convex shapes such as a square or rectangle. The reason was because concave shape structures have difficulties in formulating geometry constraints. In this paper, a new geometry constraint handling technique, which can define both convex and concave feasible regions and measure a degree of geometry constraint violation, was proposed. Evolution strategies (ESs) was utilized as an optimization tool. In addition, the constraint-handling technique of EVOSLINOC (EVOlution Strategies for scalar optimization with LInear and NOnlinear Constraints) was utilized to solve constrained optimization problems. From numerical examples, the proposed geometry constraint handling technique was verified and proved that the technique can easily be applied to structures in not only convex but also concave shapes, even with a protrusion or interior holes.