Research On Global Optimum Design Method For Shock Resistance Of Ship Systems

Naval vessels will inevitably encounter shock problems induced by non-contact explosion in service. Numerous examples in sea battles and ship trials indicate that in the impulsive environment of underwater explosions the prominent weakness revealed on naval vessels is poor shock resistance of many important equipments and installations on the board, which result in loss of system function, even operational ability and survivability. Hence, navies of each nation attach importance to design of shock resistance of equipments and systems on board. In order to improve the shock performance of vessels from the level of whole vessel, shock performance of systems should be considered at the design phases as an important design factor, and optimization should be executed on shock performance of systems from the view of whole to achieve balance with other design factors. Obviously, research on shock performance of equipments and installations on the vessels have important engineering application worth to improve the life-force and battle effectiveness of vessels.Design of shock resistance of ship systems mainly contains four parts:ship impulsive environment, shock resistance of equipments on board, assessment on shock performance of complicated ship systems and method on design of shock performance of systems. To provide a better theory for design of shock performance on vessels, aiming at some problems in the design and analysis of shock performance, particular research is conducted on these four parts in this thesis, and a suit of analysis method of shock resistance design for ship system is established, in order to provide references on design of shock performance on vessels.1)To analyze the statistics characteristics of impulsive environment, an intelligent prediction model based on improved neural network is established firstly. Taking numerical experiments as samples to train the model with improved particle swarm optimization algorithm(PSO), a set of effective prediction method is formed.For some typical vessels, through creating the randomicity model of possible attack on the vessels in services, combining Monte Carlo method, this paper summarized the correlation between statistics characteristics of impulsive environment and installation position of equipments, adopted space clustering method, space partition was conducted by statistics characteristics of impulsive environment. On the basis, the probabilistic model of impulsive environment was analyzed.2)Based on numerous data of impulsive environment, taking spectrum velocity as research object, the decaying rule in ship structure of a defined typical velocity was analyzed, concluding the relations between design parameters of surface vessels, loads and shock environment, conducting mathematical model analysis on shock environment data, aiming at making prediction formulas of shock environment explicit, so provide evidence for vessels and equipments shock design, analysis and engineering application conveniently. Besides, combining interpolation theory of shape function, the method and principle to set cases in ship trials was discussed, aiming to predict impulsive environment under different cases using finite experimental results with high degree of accuracy.3) The anti-shock ability of equipments on board was analyzed with time-domain method, taking some supercharged boiler as example. In view of the random factors which will influence the response of the equipment, the model of prediction of the shock performance of the equipment is built up based on the improved neural network method which will significantly reduce the work on mass numerical calculations. Then the shock performance of the equipment is analyzed with the help of the Monte Carlo method. The analyses include two cases; one is the equipment with flexible set and the other without flexible set. Compare the results of the two cases and provide the valuable information on the analyses of the shock performance of the equipment and the evaluation of the shock performance of the ship systems.4)Aiming to assess shock resistance of complex ship systems, fuzzy failure tree method and improved fuzzy Petri net method were presented. The corresponding shock-resistance assessment models were established. Taking the aircraft guarantee system as subject investigated, performance was analyzed under different cases, and compared the results with the answer gave by the traditional method.5) Based on the cost-effective criterion, the global optimum design of shock resistance for ship systems was implemented. With the minimum total investment for shock resistance of ship equipments and ship systems in whole life cycle as objective function, the investment assessment and loss assessment were analyzed. Three types of mathematical models for global optimum method, viz. bound for maximum total investment on shock resistance of ship system, bound for shock resistance index of ship system investigated, and no bounds. The optimum distribution methods of investment and(or) shock resistance index were analyzed. Finally, shock resistance design of some typical ship systems were analyzed with this presented optimum design method.