Research on multi-objective topology optimization design of rudder structure stiffness and flutter

Abstract With the continuous increase in flight speeds and operational performance requirements, the lightweight design of missile rudder structures has become imperative; however, the resulting aeroelastic issues cannot be overlooked. Aiming at the design ability of the internal structure of the skin-skeleton rudder structure, a study on the design methods of the lightweight rudder surface skeleton that takes into account the structural stiffness, flutter velocity, and manufacturing process constraints is made. First, aiming at the traditional radial skeleton rudder surface, based on the bending-torsion coupling frequency coincidence theory, the flutter velocity at different bending-torsional frequency ratios is studied by changing the rudder shaft torsional stiffness, to verify the design idea that the critical flutter velocity of the structure can be improved by separating the bending-torsion frequency of the rudder surface. Secondly, a compromising programming method is introduced to define an objective function that can comprehensively characterize the static stiffness and dynamic bending-torsion frequency difference. At the same time, considering process constraints such as structure size, draft, and symmetry, the topology optimization of the rudder surface is conducted with the variable density method, and the macroscopic force transmission path of the internal skeleton is obtained. Finally, based on the macro-structural topology optimization of the rudder surface structure in the previous step, the influence of dot-matrix filling on the structural flutter and stiffness characteristics of the rudder surface structure is studied and the dot matrix is filled to consider the multi-objective size optimization design for structural flutter and stiffness performance. The study results show that the multi-objective topology optimization design method is able to improve the stiffness and flutter speed, at the same time, the dot-matrix filling structure owns a promising application prospect in terms of weight reduction and flutter performance improvement of the rudder surface structure.