Application Research Of The Multi-disciplinary Design Optimization Method For Conceptual Design Of Surface Combat Ships

The general design is the core link of surface combat ship design.It is a process and method by synthetic trade-offs and integrated optimization which is involved in many different disciplines and systmes,such as general layout,navigation performance,strucutre,power,electric,weapons and so on.Meanwhile,the general design of surface combat ship is also a deepening process with repeated iteration and spiral progressive.In the whole design cycle,conceputal design takes an improtant role on optimizing overall performance of warship,enhancing the quality of general design and controlling the risk of development.However,because of the complexity and coupling of the general design of surface warships,traditional optimization methods cannot fully consider the coordination and coupling effects among the complex systems.Even with cleear input and experience,it is hard to obtain the optimization design within the global design space.In the early 1990 s,the multi-disciplinary desgin optimization(MDO)as a new research area was priority rising in the aerospace industry,and then it gradually began to be applied to other fields.In the field of ship development,the multi-disciplinary optimization method has attracted the researchers and academia's attention.The existing research has shown that by using the appropriate multi-disciplinary optimization strategy it can make full use of synergies between the various systems,so as to obtain the optimization design overall.However,the complexity and coupling of surface combat ships are more prominent during the process of general design which includes the construction of mathematical model,parametric modeling of hull profile,and comprehensive effectiveness assessment of overall program.Because of this,using the multi-disciplinary optimization method has facing more difficulties in the application of surface combat ship.It also restricts the further application on pratical engineering appliction to a certain extent.Based on above analysis,this thesis focused on the core issues of the general design of surface warships and carried out the research on the application of multi-disciplinary design optimization methods.This thesis has paid more attention on the key technology of multi-disciplinary optimization strategies,ship-type's automatic transformation technology,optimization of general layout design and approximate optimization system of the surface combat ship which provided theoretical reserve and technical support for improving the general design level of the surface combat ship.The main research points include the following five aspects:1.Adaptability analysis of several typical multi-disciplinary optimization methods in the gneral design.This thesis summarized ideas and process of MDF,CO,BLISS and other multi-disciplinary optimization methods.By using mathematical examples,comparative analysis through many aspects was carried out,such as solution efficientcy,convergence rate,stability and so on.Based on this,according to the characterisitics of general design of surface combat ship which has the mulit-systm,multi-constraint and multi-target,the advantages and disadvantages of different mulit-disciplinary design optimization method were analyzed.2.The general design structure and corresponding optimization algorithm of surface combat ships by the method of analytical target cascading.This thesis analyzed the characteristics of the general design of surface combat ships from multi-angle and discussed the contradiction,coupling and complexity in the design process.It put forward the framework of the general design structure facing the procedure-oriented design process,product-oriented composition and target-oriented decomposition,and analyzed their respective characterisitics.Focusing on the decomposition structure of the target-oriented,the thesis discussed the process and ideas of goal decomposition,coordination and optimization.Meanwhile,the thesis analyzed the adaptability of the target decomposition multidisciplinary approach and improved the method by using widening Lagrange relaxation factor of dynamic difference.Combinging with the examples,it built a simplified conceputal design optimization model and verified the effectiveness of the target-oriented decomposition framework and the convergence of the optimization algorithm.3.Parametric modeling of ship type and transformation method based on improved FFD.This thesis discussed the principle of parametric modeling of ship type.Aiming at the surface combat ship with characteristics of transom stern,bulbous bow and flare,it established the parameter systme of the mail hull profile and the parameterized main hull surface model.After analyzing,it presented the phenomenon that the method involved many parameters and existed effects between parameters.In this thesis,a method of avoiding the local coordinate transformation was proposed.The method was based on the NURBS basis function.The efficient control grid and node vector setting method can achieve global transformations of the ship by usigng a small amout of control points.On the same time,the effectiveness of the method was verified by an example.4.The mathematical model of main subject of the surface combat ship's concept design.Based on the conceptual design of surface combat ships,mathematical models of six disciplines,such as hydrostatic force,powering perforamnce,seakeeping performance,maneuverability,oveall layout,and weight center of gravity,were established respectively.For the powering performance which has mature theory,the thesis analyzed and determined appropriate solving method by weighting the accuracy of calculation and time cost.It put forward the approximate method of numerical simulation test sampling and response surface fitting model.For the discipline of overall layout and weight center of gravity which depend on the design experience,the thesis established the mathematical model which accorded with the depth of concept design reflecting important effects to the concept design by overral layout in actual engineering.At the same time,the method of calculating the hydrostatic force which corresponded to the improved FFD ship model transformation method was put forward.The applicability of different ship types was extended,and the corresponding procedure was developed.5.Multi-disciplinary optimization model and application validation of surface combat ship's concept design.This thesis systematically analyzed the optimizaion objectives,the general constraints,the design variables and the interface of the surface combat ship's conceputal design.By using the analytic hierarchy process and multi-attribute utility function to establish the comprehensive utility function,the complex conceptual design process was transformed into a simple design optimization mathematical model.Based on the multi-disciplinary optimizaion model of response surface approximation and target-oriented decomposition,the automatic interaction between various disciplines and data interface was achieved.The integrated optimization platform of concept design of surface combat ship is based on ISIGHT.In order to analysis and verficate the optimizaion results,the thesis take the conceptual design of 8,000 tons of surface combat ship as example.Results show that the application of multi-disciplinary design design optimization method in theconcept design of combat ship is effective.