Study On Direct Calculation Of River-sea-through Ships

River-sea-through Ships to avoid the loss of goods during transit, reducing the goods transport cycle is an ideal means of transport during the combined transport between the river and sea.There is no specification suitable for construction of river-sea-through ships navigating a particular route between the river and sea. Specifications promulgated by China Classification Society before also had very few provisions on River-sea-through Ships. The structural design of River-sea-through Ships mostly made use of specification about the reduction in limit navigating area dealing with structure dimension by a discount, or even directly obeyed specifications of sea ships. This method seems a little rough. In addition to the convenience of loading and unloading of goods and restrictions of waterway, River-sea-through Ships usually have a large span, long compartments, large openings and other features and their main dimensions and structures often do not meet the specifications. When this situation occurred, the method based on the ship girder theory and empirical formulas won't bear fruit. The introduction of direct calculation of the finite element method to the strength checking of River-sea-through Ship structures becomes necessary.China Classification Society is developing new rules, Rules for the Construction of River-sea-through Ships, which not only provides the structure dimension, modus, design load and other related aspects on ship safety but also provides conditions when direct computation is needed. The study on direct calculation method of River-sea-through Ships not only varies the new rule, but also helps users to understand the new rule and improve the ability of the using specification.Because of the limitation of main dimensions, direct calculation of River-sea-through Ships cannot choose a compartment model. When making finite element model of a whole ship, the outer plate of bow and stern which have a complex lines and curvature at two-way, are difficulties compared with the modeling of middle parallel body. it is the key position when modeling a whole ship. Therefore, a reasonable method to complete the modeling of bow and stern is particularly important. The second development using AutoCAD LISP and Patran PCL helps to solve this problem and provides a solution to creating the hull complex surfaces in Patran.The project in accordance with the relevant requirements of Rules for the Construction of River-sea-through Ships, take the limit dimensions to design three "concept" River-sea-through Ships as the study objects and make the whole ship finite element model before doing the direct calculation. The finite element modeling, boundary conditions, the calculation of design loads and other issues were discussed. The feasibility of the rule is verified.