Test results by 1, 000 m3 experimental LNG Ship at actual sea going (2nd report)

The recent outstanding development of computer, accompanied with such powerfull methods of analysis as FEM, has yielded the design concept “design by analysis” where the structures are not designed by “rules”, but almost entirely by “analysis”. In the application of the design based on the concept, the designers are required to analyse the each physical quantities as the stochastic valuables, and to prove the safety of the objective structures statistically.Then it is the problems how to prove the rationality of the analysed values or, if the analysis have some difficulties how to correct those, because the stochastic valuables are too difficult, though not impossible, to be simulated artificially. And it can be said that the experiments under the natural conditions are the most reliable way to solve those problems.In the sense above, Hitachi Zosen have built up the 1, 000m3 experimental LNG ship, where two types of tanks prismatic independent tank and spherical tank, were equiped. The several kinds of quantities such as ship motion, pressure and stress in the tanks and so on, were measured under the conditions where the ship ran on the actual sea. Those measured values were compiled to obtain the statistical distributions or the various kinds of the statistical quantities. And the method of analysis of the safety assessment which are being developed by Hitachi Zosen were checked by those experimental values and the problems which requires further research were pointed out.In this report, as the 2nd report, the results of the experiments as to the pressure and stress response to the ship motion, and the several kinds of the statistical distribution of stress are indicated and are investigated by the analysis.