Optimization Design Of Cabin And Typical Node Structure Of Oil Tanker

The lightweight research of ship structure plays an important role in ship design.How to obtain lighter hull structure under the premise of ensuring the safety of ships is the pursuit of researchers.The less steel consumption and the reduction of empty ship weight will bring certain economic benefits to shipyard and shipowner.As an important transport ship,the proportion of steel material of oil tanker hull increases greatly due to its double shell structure characteristics,especially for the lightweight of oil tanker structure.At the same time,the safety of the oil tanker can not be ignored.The stress concentration often occurs at the elbow plate of the typical joint,such as the rib plate,which leads to fatigue failure.In order to reduce the stress concentration of the joint,it is also important to optimize the joint.This paper takes 25000 dwt oil tanker as the research object,and studies the cabin and local optimization of the ship body.The main work contents are as follows:According to the relevant provisions of CCS "Specification for classification of steel sea vessels"(2018),the three cabin section parametric modeling of the target ship is carried out by using ANSYS Parametric Design Language.According to the requirements of the specification,the finite element calculation and strength analysis are carried out for the target hatch section,and the strength meets the requirements of the specification.The target section is optimized in different sections,the model of the hatch is divided into four areas: deck,side,bottom and transverse longitudinal bulkhead.All design variables are treated as discrete variables,sensitivity analysis is conducted with each block as optimization unit and cabin as optimization unit.The influence of the former and the latter on optimization variables is compared;experimental design,sample point selection,approximate model establishment,size optimization are carried out for each section of the cabin,and the optimization results of each zone are integrated and verified.Six typical node ship bottom structural parametric models are established.Considering the relationship between various factors and hot spot stress,the influence of different loads and different calculation methods on hot spot stress and coefficient is studied,and the appropriate load and calculation method are selected for optimization.The influence of submodel boundary conditions and independent boundary conditions on joint stress is analyzed,and the independent boundary conditions can be used for the optimization design of nodes.The multi-objective optimization of the bottom node model is carried out with the hot spot stress and structure quality as the optimization objective,and the improved shape of the joint is obtained.The parametric model of six typical node bottom local structure elements is established,the shape of welding toe is simulated,and the stress distribution near the hot spot is analyzed.The notch stress and coefficient are calculated.Considering the errors in the construction process,the distribution law of notch stress concentration factor is studied when the weld toe size changes in a reasonable range.