Lightweight Research Of Ship Structure Based On The Artificial Neural Network

Ship lightweight will be conducive to reduce energy and resource consumption (especiallythe consumption of oil and steel resources), and reduce shipbuilding costs, to reduce emissionsof greenhouse gases such as carbon dioxide to resist the global warming, to achieve sustainabledevelopment strategy.Currently, the ship lightweight research objects are mostly the local structures, and mostlyconcentrated in the tail structure optimization, plate frame structure optimization, thecross-section optimization, the cabin optimization design, lack of the overall consideration; theoptimization of the ship structure is mostly static optimization, and its constraints are mostlystatic index, lacks of considering the impact of the real ocean water and other factors on thedynamic characteristics of the ship structure; the screening of the ships optimization variables ismostly based on the experience, lacking of effective connection between the design variablesand the ship performance, such as the strength, the stiffness and dynamic performance. So thesensitivity analysis, the artificial neural networks, the optimization method and finite elementmethod are applied to the integrated study of the ship structure lightweight, the comprehensivestatic and dynamic characteristics analysis and optimization of the ship structure is done, and itnot only improves the validity and reliability of the ship structural analysis, but also improvesthe efficiency of the calculation and optimization, and gives an effective way to shiplightweight research.So, this paper puts forward lightweight research method of ship structure based on theartificial neural network, the main research works is as follows:(1) the three-dimensional finite element model of the54m bulk carrier is established onthe basis of the ship drawings and CCS Standards, then boundary constraints is applied, and thecorresponding design load, cargo load are calculated, so the whole ship structure strength andtank strength are calculated and analyzed, the most dangerous working condition, thedistribution of the stress and strain of the ship and the weak link of the intensity are obtained, itprovides reference for the design of the important parts of the ship; (2)the typical calculation method of the entrained water quality is comprehensiveevaluated, the entrained water quality of the whole ship is the calculated by the Lewis, Toddmapping method, the ship’s dynamic finite element analysis are done on the basis of them, thedynamic characteristics of the ship is obtained, to make up for the shortage of the impact of theentrained water on the ship, to lay the foundation for optimization design;(3)In combination with relevant analysis software, the typical sensitivity analysis methodis comprehensive evaluated, the design variable screening of the ship is done by the testsensitivity analysis method, the greatest influence on the main performance componentthickness are established as the optimized design variables, such as von-mises stress、max-shear stress、the total quality、the first order natural frequency、the second order naturalfrequency;(4)the common artificial neural network methods are comprehensive evaluated, theartificial neural network is established, the method of orthogonal experiment is adopted toarrange test, the training and test samples of the artificial neural network are calculated, theartificial neural network is trained and tested, BP neural network which reflects complex staticand dynamic mechanics relationship between the ship performance indicators and ship designvariables is obtained, improving the efficiency of calculation and optimization;(5)the common single objective optimization algorithm is comprehensive evaluated, thenonlinear constrained minimization optimization model of the whole ship structure isestablished, the optimization is done under the condition of allowable force, minimumthickness, frequency and other constraints, the optimal results are obtained. The optimized shipmodel is checked by using finite element software, compared to the previous, the whole shipweight reduces11.3%of the previous. The optimized ship’s dynamic and static finite elementanalysis are done, the total strength and vibration characteristic of the whole-ship are obtained,compared with the standard, the result shows the ship performance is conformed to the standardand also shows that this lightweight method not only has good feasibility, but also has the actualengineering significance and social value.