An initial hull structural modeling system for computer-aided process planning in shipbuilding

At the initial stage of ship design, it is difficult for designers to define all design information of a hull structure on 2D drawings. Thus, other designers must undertake the arduous task of translating such information to generate a 3D CAD model of the hull structure which is required at the following design stage such as the initial process planning stage. Since this task needs much time and effort, the 3D CAD model is not being generated at the initial design stage. For solving this problem, an initial hull structural modeling system is developed in this study. The applicability of the developed system is demonstrated by applying it to a deadweight 300,000 ton VLCC (Very Large Crude oil Carrier). The results show that the developed system can quickly generate the 3D CAD model of the hull structure and accurately extract the production material information for computer-aided process planning at the initial design stage.     

Improvement of ship design practice using a 3D CAD model of a hull structure

At the initial stage of ship design, a hull structural model, that is, a 3D CAD model of a hull structure is not generated by the existing shipbuilding CAD system because it is time-consuming and requires much effort. Without the hull structural model, a designer must manually calculate the production material information of a building block by using 2D drawings, parent ship data, and design experiences at the initial planning and scheduling stages. At the initial stage of hull structural analysis, the designer manually generates a structural analysis model, that is, a finite element model of the hull structure. Moreover, the piping model, that is a 3D CAD model of the pipes in the hull structure, is generated independently of the hull structural model at the detailed design stage. To lighten the burden imposed on the designer, we developed an initial hull structural modeling system in our previous study. Using this system, a designer can rapidly and easily generate the hull structural model at the initial stage of design. In this study, the generation methods of the production material information of a building block, the structural analysis model, and the piping model based on the hull structural model are developed. The applicability of the developed methods are demonstrated by applying them to a deadweight 300,000 ton very large crude oil carrier (VLCC). The results show that the developed methods can quickly generate the corresponding information or models at the initial design stage.     

Mapping 2D midship drawings into a 3D ship hull model based on STEP AP218

Standard for the exchange of product model data (STEP) AP218 has a standard schema to represent the structural model of a midship section. While its schema facilitate the exchange of ship structural models among heterogeneous systems, most shipyards and classification societies exchange information using 2D paper drawings. We propose a feature parameter input method to generate a 3D STEP model of a ship structure from 2D drawings. We have analyzed the ship structure information contained in 2D drawings and have defined a data model to express the contents of the drawing. We also developed a GUI for the feature parameter input. To translate 2D information extracted from the drawing into a STEP AP218 model, we have developed a shape generation library and have generated the 3D ship model through this library. The generated 3D STEP model of a ship structure can be used to exchange information between design departments in a shipyard as well as between classification societies and shipyards.     

A development of data structure and mesh generation algorithm for whole ship analysis modeling system

In the whole ship structure and vibration analysis, the FEA (finite element analysis) model of whole ship structure is required in the early design stage before the 3D CAD model is defined. Because ship structure has a complex curved surface, and many associated structural members, the whole ship analysis modeling job has become a time consuming job. For the effective support of the whole ship analysis modeling, a method to generate the analysis model using initial design information within the ship design process, hull form offset data and compartment data, is developed. To easily handle initial design information and FE model information, a flexible data structure is proposed. An automatic quadrilateral mesh generation algorithm using initial design information to satisfy the constraints imposed by the ship structure is also proposed. With the proposed data structure and mesh generation algorithm, whole ship analysis modeling job for various ship types can be effectively supported and these results are presented.     

基于骨架模型的船体结构快速建模

针对当前我国船舶结构设计中迭代次数多、设计存在异地性的问题,提出一种船 体结构快速建模方法。以“自顶向下”为设计思路,以骨架模型为实现载体,对船体结构特点进 行分析、总结后构建了面向船舶结构的骨架模型,给出船体结构骨架模型的定义。通过船舶结 构的骨架模型与参数坐标系实现船舶总体的快速布局设计;建立参数坐标系与船体板架之间的 关联关系实现船体结构的快速建模与快速调整,并给出相应算法;给出设计信息的组织方式并 将设计信息集成到骨架模型实现船体结构模型的完整性定义与快速建立。最后基于 CATIA V6 平台开发快速建模系统,并通过纵骨架式船体结构验证了方法的可行性。     

A distributed collaborative product design environment based on semantic norm model and role-based access control

With the boom of Internet Technology, it becomes possible to combine designers from different disciplines into one team to support product design globally. In this paper, a distributed collaborative product design environment is presented to support top-down process oriented product design. In conceptual design stage, the artifact is managed by semantic norm model (SNM). In SNM, the designers can define virtual components at early design stage and instantiate those components at later detailed design stage. By role-based access control (RBAC), different roles with corresponding permissions could be assigned to distributed designers, and the designers could concurrently modify different components of the product relevant to his or her roles. Based on the SNM and RBAC system, a distributed collaborative product design environment is developed and the top-down oriented product design process is demonstrated.     

Development of a simple model for batch and boundary information updation for a similar ship’s block model

In early 2000,large domestic shipyards introduced shipbuilding 3D computer-aided design (CAD) to the hull production design process to define manufacturing and assembly information.The production design process accounts for most of the man-hours (M/H) of the entire design process and is closely connected to yard production because designs must take into account the production schedule of the shipyard,the current state of the dock needed to mount the ship’s block,and supply information.Therefore,many shipyards are investigating the complete automation of the production design process to reduce the M/H for designers.However,these problems are still currently unresolved,and a clear direction is needed for research on the automatic design base of manufacturing rules,batches reflecting changed building specifications,batch updates of boundary information for hull members,and management of the hull model change history to automate the production design process.In this study,a process was developed to aid production design engineers in designing a new ship’s hull block model from that of a similar ship previously built,based on AVEVA Marine.An automation system that uses the similar ship’s hull block model is proposed to reduce M/H and human errors by the production design engineer.First,scheme files holding important information were constructed in a database to automatically update hull block model modifications.Second,for batch updates,the database’s table,including building specifications and the referential integrity of a relational database were compared.In particular,this study focused on reflecting the frequent modification of building specifications and regeneration of boundary information of the adjacent panel due to changes in a specific panel.Third,the rollback function is proposed in which the database (DB) is used to return to the previously designed panels.     

建筑结构平面图辅助设计系统VHAutoFraming的设计与实现

VHAutoFraming使用面向对象的参数化褓造型方法，结合建筑图的自动理解，设计了从三维到二维的正向工作流程；充分利用三维实体数据的完整性，实现各层次二维图形的自动生成和结构力学分析所需的数据模型的自动建立；并提供简明的交互方式，辅助结构设计师方便、快速、准确地设计和绘制结构平面图。     

Managing the exchange of engineering product data to support through life ship design

An approach for managing the exchange of engineering product data between geographically distributed designers and analysts using a heterogeneous tool set for the through-life design of a ship is described. The approach was developed within a pan-European maritime project called VRShips-ROPAX 2000 that demonstrated how information technology could be integrated into the design process. This paper describes the development of a common model containing neutral ship product data through a bottom-up consideration of the requirements of the tools to be integrated, as well as a top-down consideration of the data requirements for through life design. This common model was supported within an Integrated Design Environment (IDE) that co-ordinated design activity distributed across Europe. The IDE ensured that the users were provided with the right data in the right form at the right time to do the right task, i.e., that the design activity was timely and appropriate. The strengths and weaknesses of the approach are highlighted.     

Identifying and constructing elemental parts of shafts based on conditional random fields model

Semantic information is very important for understanding 2D engineering drawings. However, this kind of information is implicit so that it is hard to be extracted and understood by computers. In this paper, we aim to identify the semantic information of shafts from their 2D drawings, and then reconstruct the 3D models. The 2D representations of shafts are diverse. By analyzing the characteristics of 2D drawings of shafts, we find that there is always a view which represents the projected outline of the shaft, and each loop in this view corresponds to an elemental part. The conditional random fields (CRFs) model is a classification technique which can automatically integrate various features, rather than manually organizing of heuristic rules. We first use a CRFs model to identify elemental parts with semantic information. The 3D elemental parts are then constructed by a parameters template method. Compared with the existing 3D reconstruction methods, our approach can obtain both geometrical information and semantic information of each part of shafts from 2D drawings. Several examples are provided to demonstrate that our algorithm can accurately handle diverse 2D drawings of shafts.