A STUDY OF DIVING DEPTH ON DEEP-DIVING SUBMERSIBLE VEHICLE

Among the many deepwater activities in which deep-diving submarines ha ve been used, include marine research, deep ocean mining and submarine rescues. To resist high hydrostatic pressure and obtain more inner sp ace, the deep-diving submersible pressure hull is normally constructed by high strength steel and a simple geometrical configuration, e.g. s pherical, elliptical and cylindrical shells. The material properties, weight/volume ratio and aspect ratio profoundly influence the diving d epth of pressure hulls. The accurate calculation of strength is of pri ority in developing deep-diving submarine. In the present work, we inv estigate the diving depth of spherical and elliptical shells. Also con sidered are the geometrical non-linear and elastoplastic material beha viour of high yield steels, as well as the effect of weight/volume rat ios and aspect ratios on the geometrical configuration. High yield ste els, i.e. HY80, HY100 and HY140, are adopted here. In addition, the fi nite element procedure based on the Hibbitt and Karlsson's methodology is used to analyze the diving depth of the shells. Experimental resul ts indicate that for a spherical shell a/b = 1 and the weight/volume r atio W/V = 0.685 ton/m(3), the HY140 steel has the greatest yielding d iving depth, i.e. 5238.6 m and ultimate diving depth, i.e. 5957.9 m. M oreover, the difference between diving depth at yielding strength and diving depth at ultimate strength is 719.3 m, i.e. lower than the diff erence 1020.2 m for HY80 and 840.6 m for HY100. Although the pressure hull of HY140 steel has a deeper diving depth than the HY80 and HY100, the difference between yielding and ultimate diving depth is smaller than the others, because the ability to sustain plastic deformation of HY140 is lower than that of HY100 and HY80. According to our results, a deep diving submersible pressure hull having a larger aspect ratio, has a larger diving depth. In addition, the higher weight/volume rati o implies a larger diving depth. Moreover, the higher yielding/ultimat e strength implies a deep diving depth. (C) 1998 Elsevier Science Ltd. All rights reserved.