Research On Elastic Boundary Influence Over Hull Panel Involving Plastic Dynamic Responses

In the testing process of the simple structures,grillage structure for example,the boundary condition is traditionally selected as rigid fixing or simply support.Compared with the testing resulting from the cabin,the injury level of the grillage panel is more grievous than the cabin panel.The influence of ship movement and around part constraint attracting no enough attention,however,are critical factors over panel injury according to the simulation results.In the article,the main factors influencing panel failure is classified into boundary issue,the acting law of each is concluded and the simplified modeling is employed to simulate the panel damage.Then ultimate method of dynamic substructure considering plastic state is adopted to solve the response processes,with the influence of varying stiffness and mass matrix on natural property and response feature being considered,the details are as follows.Firstly,the boundary affection over the panel local strength is analyzed via FE method.The boundary constrained panel is computed to obtain the kinetic characteristics,and the finite element modeling of cabin and bulkhead constraint,which results is compared with the origin one’s origin whole hull,is implemented to verified the influence of the overall hull girder impacting over the outside panel damage.Then the varying length cabins are put into contrast,and a terminal envelope curve of the explosive distance and cabin length versus odds deflection is accomplished.Secondly,the simplified kinetic boundary modeling of panel computing is established according to the modal theory.The overall velocity,based on incidence wave energy,is obtained according to moving property of the waterline structure under a certain calculation condition.Then the whole modeling is simplified into a constitution according to the energy conservation law,which belongs to a single degree of freedom consisting of stiffness and mass matrix.And an ultimate participation level of formation is verified by increasing the orders of the formation.Thirdly,a method of solving elastic-plastic responses using substructure method is applied.Numerical modeling consisting of three substructures,which including a modal condensation elastic model and all geometric information,is founded based on fixed interface modal synthesis method.The validity of elastic computing is verified by incremental Newmark-? solving tool,and using finite deformation theory to get the strain and stress in material plastic stage,then computing method is accomplished after an updating stiffness matrix and the equation convergence in the iteration steps.Fourthly,the influence of the varying around structures on the plastic element dynamic response is carried out.The influence degree over the coupling boundary is analogical to the around structure alteration of stiffness and mass matrix by the results of the element stress.The response law of the plastic response is obtained by the varying from the stiffness,mass count and position,either obtaining the influence of mass and stiffness over velocity and vibration properties.And the final effect of the panel plastic injury on the whole model is analyzed,gaining an influence of factors of position,area size and orientation.