Application Of MDO Method To 7000m HOV General Design

The human beings are facing critical problems such as population, resource and environment. With the rapid development of global economy and the increasing of population, the marine resources are going to be most exploited. Deep-sea HOV can dive to deep-sea locations with various kinds of electrical equipments, mechanical devices and scientists, so that exploration, investigation, exploitation and related work can be carried out effectively. HOV has several advantages by contrast with other kinds of submersible: better interface between technician and machine, and involving higher rank of science research. In order to defense national resource and increase the skill of exploring resources, the important project of"7000m HOV"is established by our country.The dissertation is am important part of the magnitude country 863 project of"7000m HOV". Here MDO is used for framework designing of HOV as a new kind of method so that an optimal framework can be designed under the constraint of design request and performance target. And by doing these work, we researched how MDO can be used in underwater engineering effectively. The main improvement work includes:(1) Four sorts of MDO framework such as MDF, IDF, CO and CSSO are studied and illuminated clearly. Optimal results of Heat pole problem calculated by different MDO frameworks of MDF, IDF and CO are compared. According to the comparison, the key factors to influence the results are the sort of framework, the initial values and the optimization algorithms. The best result is got under the framework of IDF. After the shortcoming of IDF framework is analyzed and improved, BLH framework is brought forward as a new and better framework for 7000m HOV MDO design.(2) With BLH framework, MDO method is applied to AUV general conceptual design. While the requests of AUV design performance are met, the objectives of minimizing gross weight and maximizing propeller power and payload length are achieved. And at the same time, the influence of initial values and optimization search strategy to the optimal results is investigated.(3) The subsystem of general MDO design for 7000m HOV is decomposed based on the device's characteristics and types, optimization target and BLH MDO design traits. And then each of the subsystems is analyzed, the mathematics models of them are set up and the design and output parameters are summed up. Based on these works, the MDO framework is integrated, the objective functions are defined and the constraint condition is set.(4) The structure subsystem of 7000m HOV's pressure hull is mathematically analyzed by the method of VCM. For the accuracy and complexity of different complexity analysis method are different, firstly, the ultimate strength of pressure hull is mathematically analyzed and calculated by ANSYS, and then the empirical formulation is modified according to the modified factors, which are gotten by the accurate model of ANSYS. So that the calculation accuracy will be improved and the calculation time will be reduced after the analysis model of pressure hull structure is integrated.(5) The optimal design of 7000m HOV will be decided by the judgment functions that is carried out by the way of using the BLH MDO for the general design of 7000m HOV, selecting the main control variables by using the Latin hydrocube to analyze the relationship among design variables and objective functions, and comparing the result of various initiative value and optimization searching strategy.The items (1), (2) and (5) in above-mentioned works embody the innovation researches of this thesis. Through the studies,the following main conclusions can be drawn:(1) This is the first time that MDO is used to 7000m HOV design and a relative integrated optimization model is set up. Some further design improvement pints are found by comparing the current design. So the applicability of MDO for massive engineering system is proved.(2) The BLH framework based on improvement of IDF is brought forward for the first time, which is dealt with the general design of AUV and HOV.(3) The MDO design of AUV general performance is performed based on BLH framework. The relationship analysis of design parameters and objective functions is carried out by using DOE. For the reason of multi-objective functions of AUV general MDO, Judgment function is brought forward to get the optimal results.(4) According to BLH framework, 7000m HOV MDO design is decomposed into five subsystems, and the mathematic model of 7000m HOV MDO design is set up by parameter modeling method.