The Lightweight Research On Ship Structure Based On Topological Optimization

As a hot subject researched in recent years,optimization design of ship structure is committed to reduce the steel weight of ship while ensuring its structural strength.Different from general size optimization,topological optimization design in structure aims to find the optimal distribution way in material and the best force transferring path.At present,the research on optimization design of ship structure mainly focuses on the size optimization in the structural component of the ship while relatively less attention was paid to the topological optimization in structure.On the other hand,about the optimization of ship structure,for high speed trimaran,it has to bear wave bending moment in horizontal direction and torsional moment due to complex ship structure.As a result,the ship has a great increase in overall weight and the component size has to be expanded as a way to guarantee the rigidity and strength.However,the high speed ships are sensitive to their own weights no matter which types.How to resolve the conflict between reducing the weight and ensuring the rigidity and strength has been a significant issue that need urgent solution in the designing of high speed ships.Topological optimization in structure is identified as one of the most challenging research field that is promising in potential economic benefit while research on topological optimization design is very significant in practical optimization and lightweight designing of engineering structure.The paper focuses on the bulkhead structure of trimaran to analyze and explore the optimal topological form in structure based on the fundamental principle and analysis procedure of topological optimization design.(1)In this text,the unit material density is defined as topological optimization variable on the basis of topological optimization method in continuum structure as well as density model of SIMP material.Meanwhile,the static response of structure acts as constraint condition of optimization combined with equilibrium equation in finite element calculation.Other than common topological optimization calculation,the text defines the unit volume function as objective function of optimization,which can improve the efficiency and stability of computation in topological optimization.The relational expression of optimization variable can obtain through optimal criteria that confirmed through introducing optimal criteria together with K-T condition.By doing the above,a complete mathematical model of topological optimization can be finished.(2)The author committed to two tasks to verify the reasonability and accuracy of topological optimization method in the text:firstly,the author selects the classic cases of topological optimization-L board structure in the three literature to compare the optimization solution.Next,the author chooses the topological optimization module of ANSYS to conduct optimization solution and compares the result.It turns out that,the topological optimization method applied in the text can obtain topological configuration which boasts clear outline,more homogeneous,coordinated and structured sizes in all parts without accessory structure.(3)Focusing on bulkhead structure,the text applies finite element method based on?Rules for the Classification of Trimarans?of and Lloyd' s from English and uses finite element software ANSYS to complete finite element analysis of the bulkhead structure under various working conditions as a way to ensure that the structural strength can meet the needs of design standards.At the same time,targeting on stress transfer and distribution,to conduct topological optimization in target design area of the structure to find a design scheme that is more reasonable in structural,economical performance and crafting.(4)Based on two algorithms of topological optimization design(control algorithm and acuity algorithm based on optimal principle),the author,through comparing the calculation results,finds that control algorithm is superior to acuity algorithm to some extent when optimizing the bulkhead structure researched in this text.(5)Using topological optimization to find the optimal topological configuration while ensuring the strength and performance of structural component.By doing this,the volume of design area in bulkhead structure reduces by 50%as a way to finally achieve design and research on lightweight of ship structure through the optimization scheme.