面向审核流程的船舶CAD系统建模方法研究

System modeling method research of ship CAD for audit process

为提高船舶CAD建模效率,同时为CAE分析和船体结构设计程序(SDP)校核提供通用数据模型,设计并开发了一套面向审核流程的船舶CAD系统.首先考虑审核流程的需求,采用几何与数据相结合的方式描述船舶模型,所有船舶构件均采用无厚度的几何片体表示.其次建立包含发布模型、设计主模型和工具模型的三层板架模型,以板架属性的形式记录板架及其附属结构的几何关系,并结合自定义结构导航树、通用三维建模软件NX装配树和特征树组织管理板架及其附属结构.然后基于轻量化数据库SQLite设计面向全生命周期的标准库系统,用来存储和管理船舶标准数据,确保快速查询.最后通过参数化建模与基于自定义特征技术的结构建模方法,快速生成船舶模型.该系统具有较强的交互性和稳定性,建模效率高且模型数据量小;模型经过数据转换可直接进行CAE分析和SDP校核,避免重复设计;数据库技术的使用实现了CAD、CAE和SDP模块间的数据共享,解决了数据分散不一致的问题;自定义结构导航树符合专业船舶设计人员的使用要求.

To improve the efficiency of ship modeling and provide an original data model for CAE analysis and Structure Design Program (SDP) checking, a ship CAD system for the audit process is designed and developed. By considering the needs of the audit process, both the geometry and the data of the ship model are described, with all ship structures represented by zero-thickness sheet body. Besides, a three-laminated panel model including release model, master model and tool model is established to record the geometric relationship between the panel and its subsidiary structures in the form of panel attributes. The panel and its subsidiary structures are managed by combining the custom structure navigation tree and the assembly tree, the feature tree of the generic 3D modeling software NX. Furthermore, for storing and managing the ship′s standard data and ensuring inquiry efficiency, a standard library system for the whole life cycle is designed based on a lightweight database named SQLite. Finally, the ship model is generated quickly by parametric modeling and structural modeling based on custom feature technology. It is verified that the system proposed in this paper has strong interactivity and stability, and the modeling efficiency is improved with smaller amount of data. After the data conversion, the CAD model can be used directly by CAE and SDP, thus avoiding repetitive design. The use of database technology achieves data sharing between CAD, CAE and SDP modules and solves the problem of data inconsistent and dispersion. The custom structure navigation tree meets the requirements of professional ship designers.