Connector Design And Dynamic Characteristics Study Of Very Large Floating Structure

The very large floating structure is a cutting-edge platform in ocean engineering that emerged from the national strategic demands in naval defence and natural resource development. It is a typical nonlinear network system because of its massive size, flexibly connected multiple modules and hydro-elasticity effects. The paper, based on a massive scale floating airport as the research background, attempts to apply the latest theory of nonlinear network dynamics to the dynamic study of very large floating structure.Very large floating airport is a typical nonautonomous network system with flexibly connected modules in a chain-like topological form. This paper presents a generalized network model for the floating airport using linear wave theory, dynamical model of a single floating body, connector model and model of mooring system. The modeling method is universal and extendable to very large floating structures with various complex network topology structures and mooring constraints.Considering that the mechanical characteristic of connector model between floating modules has a crucial influence on the dynamic response of floating airport, the paper puts forward and investigates three new types of connector model, namely parallel-articulated-flexible connector model, cross-articulated-flexible connector model, and composite-flexible connector model. In numerical simulations, the nonlinear responses of surge, heave, pitch motions and loads of three connector models are respectively analyzed. It implied that compared with the results of nonlinear network analysis, the classical linearization approach may severely underestimate the actual dynamic response and the connector load. The effect of three connector models on the nonlinear response characteristics and the connectors load features have been investigated. The results show that composite-flexible connector model may more effectively restrain the dynamic response, has better load characteristics, and its parameters domain for the safety design is the broadest. Thus it is the most appropriate configration. The paper further discusses the complex network dynamics behaviors of floating airport, including the phenomena of network synergy and synchronization effect of response.This paper also introduces a new concept of network dynamic stability into the field of ocean engineering, based on the amplitude death to study the global stability of floating airport. The onset of amplitude death associated with two key parameters namely connector stiffness and wave period is illustrated, and the influences of the three connector models on the stability are analyzed. The results show that amplitude death parameter region of the floating airport with composite-flexible connector model was broadest, and the system global stability was prominent. It provides a theoretical guidance for further optimizing design of connector structure model. Connector configration has a great influence on the global dynamic stability of the floating airport, and it is of great significance to design effective and safety connector model for the research and development of very large floating structures.