Simultaneous layout and topology optimization of curved stiffened panels

Simultaneous layout and topology optimization of stiffened panels is investigated in this paper by a new level-set-based method. Specifically, plate elements are used to construct a stiffened panel structure. The level set method is then used to manipulate the stiffener layout, with curved members allowed. A free-form mesh deformation method with a control mesh is utilized to adjust the finite element mesh. The level set method is also used to optimize the internal topologies of the stiffeners. Both mass minimization with buckling constraint and critical buckling load factor maximization with mass constraint are investigated. A semi-analytical sensitivity analysis is performed, and the optimization algorithm is outlined. For the buckling-constrained problem, the p-norm function is used to aggregate many buckling modes and a gradient-based optimizer is used with an adaptive scaling method to enforce an exact control of the buckling limit. Numerical investigations demonstrate and validate the proposed method