Topology optimization of fluid–structure interaction problems with buckling constraints

In many engineering applications, structures immersed in fluid flow must withstand not only external moving fluid loading but also potential instabilities arising from fluid–structure interaction. Fluid-induced instabilities such as structural buckling, can lead to sudden and catastrophic failures, especially in slender structural members in compression. While classic fluid–structure interaction topology optimization studies often focus on improving stiffness or reducing mass, the possibility of buckling under fluid-induced loads has not yet been considered. To address this gap, we proposed a framework to incorporate buckling constraints into fluid–structure interaction topology optimization. This enables the design of structures that are not only lightweight and stiff but also stable. We have extended the existing topology optimization of binary structure method with augmented Lagrangian multipliers to stably optimize fluid–structure interaction problems with buckling constraints. Numerical examples validate the efficacy of the proposed approach, demonstrating significant improvements in optimized structures for stability against buckling. To the best of the authors’ knowledge, this is the first study considering stability for fluid–structure interaction optimization. The proposed buckling-constrained optimization framework for fluid–structure interaction problems benefits the engineering design of hydrodynamic and aerodynamic structures towards practical application.