Study On Topology Optimization For Ship Mid-section Structures And Application System Development

Realizing lightweight ships is the development direction of future ship design technology.As the core of the lightweight technology,ship structure optimization design methods are urgent for theoretical upgrading and technological innovation.At present,the application of structural optimization theory in the field of ship design is mostly concentrated on size and shape optimization,while the application results of structural topology optimization with higher weight reduction benefit are relatively less.For this reason,this paper explores the right topology optimization design method for complex ship structures,taking the midship section structures of a dredger and an oil tanker as the research objects,on which topology optimization study is carried out from the structural design level.It is expected to obtain better structural forms and provide theoretical basis as well as engineering reference for the ship structure design to some extent.This paper mainly deals with the following research contents:（1）A new material interpolation model is introduced.Genetic algorithm and bidirectional evolutionary structure optimization method are combined to construct the G-BESO method to solve continuum structures’ maximum stiffness problems under volume constraints.Through benchmark designs,G-BESO is proved more efficient than classical methods.（2）Local stress constraints are converted to a global strain energy constraint based on the distortion energy theory,then a structural minimum weight optimization model under stress and displacement constraints is established.Calculation formulas for elemental sensitivity are deduced first,then the Lagrange multiplier method is employed to deal with multiple functional constraints including stress and displacement constraints,forming a complete optimization solution process.（3）Based on the methods proposed in this paper,a general continuum structure topology optimization application system is developed using Python,Py Qt5,and VTK to facilitate the theoretical research and engineering application of structural topology optimization.（4）Aiming at the scheme design stage,parameterized finite elment modeling of a tanker’s mid-section structure is realized.Four calculation conditions are determined in accordance with the requirements of the standards.Empirical method and the analytic hierarchy process are used to determine the weight factors of each working condition,based on which,maximum stiffness optimization study on the mid-section structure under multiple working conditions is carried out.（5）Taking the pump cabin and the engine room as the structural calculation model,with sub structure and design domain elaborately selected,the midship section structure of a cutter suction dredger is optimized for maximum stiffness design under volume constraints,minimum weight design under stress and displacement constraints.Based on the optimization results,a new structural design scheme is decided.