Ultimate Strength Research Of Ship Structure Based On Combined Theory Of Strength And Stability

The stability theory is completely separated from the strength theory in history. In theearly1980s，combined theory of strength and stability(CTSS) which is put forward by LuoPeilin shows that the stability theory is powerfully integrated into the strength theory. And hesolved the world-famous problem of ultimate strength prediction on the pressure sphericalshell by using it.At present, CTSS is still being improved. And its application areas are limitedin terms of pressure spherical shell. This thesis aims at improvement of CTSS, mainlyconsists of the following aspects:(1) It is applicable to use the PL model to describe the stress–strain curve, stress–shear strain curve and tangent modulus factor curve of the material such asSteel HT32and Q235.The proportional limit formula which is exported by the PL model,can calculate the value of the material proportional limit quickly and accurately. Itprovides an effective method for the determination of material proportional limit.(2) The simple PL model is put forward and it is concluded that the simple PL model isconsistent with the Jobnson—Ostenfeld’s plastic correction formula and rules.(3) Value calculations of n-factor show that the stability theory is powerfully integrated intothe strength theory. The analytical formulas of n-factor prove that combined theory ofstrength and stability(CTSS) which is put forward by Luo Peilin is correct. It Also pointsthe way to the feasibility of CTSS(4) CTSS is also confirmed by auxiliary function method in the classical structural mechanics.(5) Through n-factor’s analogy analysis of plate, CTSS was able to expand on the calculationof the ultimate strength of hull structure. And compares the project calculation results withthe finite element method, empirical formula and test.(6) Improves the selection of the ultimate strength failure mode of stiffened plate anddiscusses the feasibility that this selection method is applied to ultimate strengthcalculation of ship grillage structure.(7) Through N-factor’s correction calculation of elastic foundation beam structure, the theoretical formula is improved on ultimate strength calculation of the pressure shell. Andcompares the calculation results with test.This thesis systematically discusses calculation principles of CTSS. Through n-factoranalogy analysis of plate, CTSS was able to expand on the ultimate strength calculation ofhull structure. This is a new calculation method for the ultimate strength prediction of hullstructure. Comparing the project calculation results from the finite element method, empiricalformula and test, the application and extension of CTSS on hull structure are successful.