The Research Of AUV Structure Power Flow Distribution Characteristics Under Propulsion System

Autonomous underwater vehicle is a significant approach to research the ocean andaccess the rich resources of the sea. With the development of the marine and thecomprehensive international security, underwater craft is going to face more rigoroussurroundings, such as growing working time and heavy working conditions. In orderto ensure AUV can work safety in a complex environment, it is necessary to study thestructural fatigue. At the same time, we feel it valuable to research the structuralfatigue using the power flow propagation characteristics. This article discussed depthin the power flow propagation characteristics of the small torpedo-AUV which has aincentive propulsion system In the stern.At first a mathematical model based on the wave equation about the power flowmethod is formulated for the shell and the cylindrical shell. We have obtained therelation curves between the input power flow and the shell ring frequency andclarified the propagation characteristics of vibration power flow in a cylindrical plateand shell plate structure.When we research the power flow distribution characteristics of AUV which isincented by propulsion system using the finite element technology, we should affirmthe model boundary conditions and kinetic analysis firstly. This article will introducethe small modular AUV from its shaping shell、distribution module、assignedinstrument、connected institutions and cross propeller propulsion system section. Withthe finite element analysis model based on the geometric parameters, we divide thismodule into QUAD4node unit and make good preparing for the pre-processing ofdynamic analysis.Calculating the dry mode and wet modal of the AUV with the finite element enginevalue solving and virtual mass solving, this article has got the natural frequencymodes in the vacuum state and the depths water state, indicating that the relationshipbetween water pressure and shell modal. After we get the frequency which is ensuredby harmonic response analysis and the thrust force which is affirmed by CFX model,we have determined all the boundary conditions. Using harmonic response analysis, we get the dynamic response curve of shellridge line feature point which depends on small modular torpedo AUV structure.Referencing to the structural intensity and the result of harmonic response analysis,we can get two types of relationship curves. One reflects relationship betweenstructural intensity of small modular torpedo AUV structure and frequency ofexternally applied load. The reflects relationship about propagating structural intensityof AUV. Finally using the PCL of the PATRAN, we get the power flow contour mapsof AUV. The articles reveal the power flow transmission characteristics of underwaterrobot with propulsion system and contribute to provide a new way of thinking aboutresearching the fatigue of AUV. Finally, using FEM optimization platform combinedwith the idea of vibration power flow, we get the optimal solution of the shell size andcontrast the output optimization results in the form of a spider diagram.