A consistent co-rotational method for fluid-structure interaction dynamic analysis of 2D flexible beams

Abstract

This paper presents a consistent co-rotational method for the dynamic analysis of two-dimensional (2D) slender flexible structures in marine environments, effectively handling arbitrarily distributed loads and realizing fluid-structure interaction (FSI) analysis within the co-rotational framework. First, the beam element motion and deformation are described based on the co-rotational framework, and consistent tangent stiffness and mass matrices are derived via the variational method. Second, combining the principle of virtual work, the consistent load equivalence formulation for concentrated and distributed loads is derived using identical shape functions, and the fluid load model is established based on the Morison equation. Finally, the FSI equations of motion are established, and the nonlinear system is solved efficiently using the HHT method with a modified Newton-Raphson strategy. Numerical examples of 2D flexible beams in air and water analyze static and dynamic responses under different discretizations. Results compared with commercial software verify the method's correctness and effectiveness. Furthermore, dynamic analysis of a top-tensioned riser under uniform current indicates that the proposed method maintains high accuracy and computational efficiency even with fewer elements.