Page 367 - Practical Design Ships and Floating Structures
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Recently, Computer Integrated Manufacturing System (CIMS) for ship building has been studied (for
example Ship & Ocean Foundation 1989-94) and now the concept is practically applied in the design
and manufacturing process in many shipyards. Furthermore, the concept of the life cycle support such
as CALS concept is proposed in which not only the effectiveness of the design and manufacturing
processes but also the effective operation and maintenance of ships are considered.
For the effective maintenance of the ship structures, a new concept of an information system of
damages of ship structures has been studied by the authors (Kawamura et al. 1998,2000). In this paper,
we firstly describe about the concept of the information system and about the object oriented data
model for crack damages used in the system. Second, the prototype system constructed on an object
oriented database on an engineering workstation is demonstrated. Thirdly, based on the proposed
information system, a ship inspection supporting system by using a portable (wearable) computer and
virtual reality technique is described.
2 CONCEPT OF AN INFORMATION SYSTEM OF DAMAGES OF SHIP STRUCTURES
The role of the information system of damages of ship structures can be considered as (1) management
of the health of an individual ship, (2) storage of the information related to the damages of the ship,
and (3) estimation of the detected damages for the appropriate countermeasure. To realize such
functions, we proposed a concept of an information system as shown in Fig.l(a). In this concept, the
information about damages such as crack or corrosion obtained in surveys is stored in an Information
Database. Since the detail infomation such as the location or the condition of the damages are
important for the evaluation of damages, not only the information of damages itself but also the
information about the 3-Dimensional (3D) hull structure of the ship is stored in the database. In the
Assessment System for damages of ships, risk of the damages is assessed and repair plan or operation
plan are drafted based on the information in the database. It is possible to say that the Information
Database can be regarded such as a medical record for a certain ship and the Assessment System for
damages of ships aids the evaluation and planning based on the information stored in the database. For
the efficient use of the proposed information system, inspection with high detectability of damages and
a convenient recording of the damages to the database are necessary. In this study, we also proposed 9
ship inspection supporting system by using a portable (wearable) computer as shown in Fig.1 (b).
3 PROTOTYPE SYSTEM OF THE INFORMATION SYSTEM
3.1 Data Model for the Information System
The prototype of the information system of damages of ship structures was constructed assuming that
the information of a certain ship is managed in a certain organization. The target ship of the prototype
system is assumed to be a single-hull tanker, and a simple structure with 4 transverse spaces including
transverse bulkhead is considered in the prototype system. Since the object oriented data structure is
generally used in development of product model, an object oriented database (OBJEZTIVII'Y 1993) is
used for the data model of the information system.
As defined in the data model of CIMS, the ship hull structure is defined by Member-objects and
Connect-objects which represent joint information such as weld or slots. For the damages, the data
model for corrosion and crack was proposed by Kawamura et ul. (1998). To construct the data model
for damages, we consider that the data model can indicate (1) the location of the damage and the
damaged structural members, (2) the condition of the damage such as configuration of the damage,
and (3) the time when the damage is detected. Here, the definition of the crack at the intersection of
longitudinals and transverse members is described as an example of the data model.