3D Ship Modeling And Damage Stability Calculation Based On CATIA

The continuous development of computer-aided design(CAD)technology makes the shipbuilding industry full of challenges and opportunities.Rational use of CAD technology can effectively improve design quality and efficiency and shorten design cycle.Computer-aided technology is widely used in the field of ships,but general commercial design software has a low degree of compatibility with ship design and without integrate required performance calculations.Therefore,it is necessary to combine design with performance calculation for secondary development of design software.The curvature of the bow and stern varies greatly.The skinning method is used to directly build the entire ship surface,and the smoothness of the bow and stern surface is poor.Based on the lines plan of ship in Auto CAD,this paper uses the Object ARX development tool to perform non-uniform interpolation of each waterline and deck lines.The interpolated point coordinates are imported into CATIA,build the hull surface in sections,and refine the generation of the bow and stern surfaces of to ensure its smoothness.Traditional ship subdivision is mostly expressed by two-dimensional drawings,which is less intuitive.The subdivision parameters are not bound to model features and cannot be quickly modified.Aiming at the above shortcomings,this paper develops a three-dimensional subdivision program based on CATIA in a top-down approach.The program defines two ways to establish 3D inner shell edge lines.The first one is based on Auto CAD inner shell knuckles,using Object ARX to extract the coordinates,and then using csharp to import CATIA to create each edge lines.The second is based on the inner shell edge position and size parameters to generate all lines.Through transverse bulkhead frame position,the number of longitudinal bulkhead and the number of vertical subdivision feature to realize rapid subdivision of the cargo area and automatic generation of compartment models.Based on the CATIA knowledge engineering module,add the subdivision parameters to the model file,bind them with the corresponding characteristics through formulas,realize dimension driven,facilitate the modification of the sub-cabin scheme,and improve the reusability of the model.By defining rules to constrain parameter boundaries,the fault tolerance of the subdivision scheme is improved.Ship damage stability is mostly achieved by two-dimensional numerical integration methods,which is complicated to calculate,and the calculation error depends on the accuracy of integration.In this paper,the secondary development of CATIA by csharp,based on the three-dimensional models of the hull and compartments,realizes the damage floating state calculation,damage stability calculation and free surface correction.Calculate the tilting moment under different loading rates and different heel angles based on the three-dimensional solid model of compartments to obtain the maximum moment for free surface correction.Through multi-threaded programming,the whole task of damage floating state calculation,damage stability calculation and free surface correction is divided into multiple sub-tasks,which reduces the solution time.Based on the lines plan of ship in AutoCAD,completes the extraction of data points coordinates,and completes the smoothness optimization of the hull surface model based on CATIA.By defining the three-dimensional subdivision parameters and combining with the inner knuckle lines,the ship’s rapid subdivision was realized.Based on the CATIA knowledge engineering,the rapid modification of the subdivision scheme was realized,which reduces the time-consuming repetitive work and improves the design efficiency.Based on 3D model,the automatic calculation of damage stability and the correction of free surface are realized through csharp,and the program is optimized through multi-threading,which improves the efficiency of program calculation.The program developed in this paper combines the general design of ship with the performance calculation,which has greater practicability.