Research On Structural Dynamic Collapse Characteristics Of Flat-type River-sea-going Ship

There are many advantages for river-sea-going ship,such as high transport efficiency,low cost and less cargo damage.Due to the restriction of natural channel and bridge clearance height in the middle and lower reaches of the Yangtze River,riversea-going ship is usually designed with flat-type.Its structure is easy to occur dynamic buckling and yielding under the action of dynamic wave load which may lead to serious wreck.Therefore,the research on the dynamic response of flat-type river-sea-going ship’s structure can provide technical support for the safe,reliable and reasonable structural design.In this paper,the typical plate panel and stiffened plate of river-sea-going ship are taken as the research object.The structural dynamic buckling and yielding are investigated by combined the theoretical analysis and numerical calculation.The failure conditions,collapse modes and ultimate strength of ship structures under dynamic load are systematically researched.The main works are summarized as follows:（1）Combining thin shell theory and Bolotin’s dynamic stability theory,the stability control equation of rectangular panel under periodic load is derived.The calculation formula of dynamic instability frequency is derived and the dynamic instability region of panel is solved.The effect of boundary conditions and linear damping on the dynamic instability region of structure is clarified.（2）Based on Lagrange’s equation and Hamilton’s variational principle,the matrix equation of structural dynamic stability was deduced and the Bolotin’s method was adopted to convert the dynamic stability problem into solving the generalized eigenvalue.Then,the matrix of four-node shell element with twenty-four degrees of freedom is derived based on the MITC plate theory.The program for solving the dynamic instability region of the structure is developed with Matlab language.The program is used to analyze the dynamic stability of typical stiffened plate structure of the river-sea-going ship.The influence of the static load coefficient,parameters of stiffener and section parameters of stiffened plate on the dynamic instability region is discussed.（3）The dynamic collapse characteristics of stiffened plate are researched using nonlinear finite element method.The dynamic response of stiffened plate in the bottom of river-sea-going ship is investigated in the static load and dynamic load.The dynamic ultimate strength and collapse characteristics of stiffened plate are discussed on the strain rate effect,initial deformation,dynamic load period and outboard water pressure.The structural failure mode under the static load and dynamic load is analyzed respectively.In this paper,the dynamic analysis of the river-sea-going ship structure is performed to investigate the failure mechanism and collapse characteristics under the dynamic load which can provide the theoretical and technical supporting for the reasonable and reliable structural design of the river-sea-going ship.