Developments of a mixed finite element substructure—subdomain method for fluid—structure interaction dynamics with applications in maritime engineering

Abstract

Theoretical development of a mixed finite element substructure—subdomain method for dynamic analysis of fluid—structure interaction systems (FSIS) with applications in maritime engineering is summarized in this paper. Governing equations for FSIS are presented. Boundary conditions for air—liquid interfaces are formulated to account for mass density discontinuity of different fluids. The frequency shift technique is demonstrated for FSIS, which establishes a basis for the design of an algorithm for the purpose of dynamic analysis of structure, fluids, and their interactions. A flow chart of the computer program is provided to better illustrate the implementation of the numerical method. Four problems in maritime engineering are simulated using the developed fluid—structure interaction analysis program (FSIAP). Problem 1 investigates the sloshing frequencies of a liquid tank and its dynamic responses to a sinusoidal base motion and El Centro earthquake excitation, respectively. Problem 2 analyses the transient response of a liquefied natural gas (LNG) tank—water system to an explosion wave in the water. Problem 3 studies a structure—acoustic—volume system subject to human footfall impacts, which may explain the ‘character’ of the footstep noise claimed by people, such as ‘thuds’, ‘thumps’, and ‘booming’. Problem 4 investigates the dynamic response of an onshore LNG storage tank subject to an impact load. The numerical results are analysed to provide the guidelines for design of maritime products involving FSIS.