Jong-Gye Shin

Relations between Input Parameters and Residual Deformation in Line Heating process using Finite Element Analysis and Multi-Variate Analysis

Sequential process of roll-bending and line heating has been used to deform the curved hull-plates in shipyards. A growing interest for the mechanization or automation of the line heating process has been noted. Relations between heating conditions and residual deformations are important components needed for the mechanization. The residual deformations are investigated by using a thermal elastic-plastic analysis based on the finite element analysis(FEA). Several experiments are also performed to examine the validity of the results of FEA. The input parameters of line heating are suggested by dimensional analysis of line heating. The dimensional analysis can extract the primary input-parameters of line heating. The relations between the heating conditions and the residual deformations are set up by multi-variate analysis and multiple-regression method. This study suggests a method for the relation between the heating conditions and the deformations lying under the line heating.

Tolerance Analysis Considering Weld Distortion by Use of Pregenerated Database

A general and efficient methodology has been developed to analyze dimensional variations of a welded assembly, taking into account of weld distortion. Weld distortion is generally probabilistic because of the random nature of welding parameters such as the welding speed, maximum welding temperature, ambient temperature, etc. The methodology is illustrated by a very simple example of two perpendicular plates fillet-welded to each other. Two steps comprise the methodology: establishment of a weld distortion database and tolerance analysis using the database. To establish the database, thermoelastoplastic finite element analyses are conducted to compute the weld distortion for all combinations of discrete values of major welding parameters. In the second step of tolerance analysis, the weld distortion retrieved from the database is taken into account in addition to the dimensional tolerances of the parts. As a result of such an analysis, sensitivities of the assemblys dimensional variations to the part tolerances and weld distortion are obtained, which could provide a guideline for improving dimensional quality of the assembly.

The Determination of Heating Shapes and Locations for Triangle Heating

Thermal forming is a method to form a curved plate by inducing local shrinkage and angular distortion through heating and cooling. In this approach, two different methods are available: line heating and triangle heating. Among them, this paper discusses triangle heating and presents algorithms for determining heating shapes and locations. The heating shape is determined by using the in-plane strain distributions, which are calculated by nonlinear kinematics analysis between the designed and initial shapes, field survey results, and mechanics based on the neutral axis. To predict the angular distortion and shrinkage in various heating conditions, a functional relation of residual deformations is formulated. For the formulation, multivariate analysis and multiple regression techniques are used with data obtained from experiments of unit triangle heating and numerical analysis. Using the determined heating shapes and the functional relation for the residual deformations, a correct triangle heating position is determined by an algorithm, which can predict qualitatively correct angular distortion and shrinkage in the interior and quantitatively correcr distortion values on the edge. Finally, analytic verification of the proposed method hcs been done by applying the method to a convex type plate used in the field. The proposed work can be used for automation of curved plate fabrication in the shipyards.

Plate Flattening Analysis in Line Heating Process using Bending Strains

In the line heating process, only angular distortion whose direction is perpendicular to that of a heating path is expected. However, it is observed that a deformation is induced in the direction of the heating line. Because of this, during forming a saddle type plate we experience unfavorable deformations in the unintended direction. In this paper we discuss the unwanted distortion in the manufacturing process by analyzing intermediate plates of saddle type during fabrication. For this analysis we consider the longitudinal and transversal directions separately and use the bending strain for the analysis.

Development of a Naval Ship Product Model and Management System

Abstract The Korean navy has made many efforts to apply the concepts of PLM (Product Lifecycle Management) and M&S to its naval design and production. However, most of the efforts that have being applied to some acquisition processes, focused only on the element technologies without information models and data frameworks. This study discusses an information model of naval ships for advanced nava l acquisitions. We introduce a naval ship product model, and it refers to the DPD (Distributed Product Description) concept of SBA (Simulation-Based Acquisition). To realize the product model concept, we design a data architecture and develop a Product Model Management System (PMMS) based on a PDM System. It is validated through the case study of building the product model of the battle ship that the PMMS has the applicab ility to effectively manage the naval ship acquisition data on the basis of a 3D product mo del. ※Keywords: Naval ship producr model(함정 제품모델), PLM (제품수명주기관리), PDM (제품데이터관리), SBA(시뮬레이션 기반 획득) 접수일: 2007년12월8일, 승인일: 2009년1월5일 g교신저자: dk5@snu.ac.kr, 02-882-3563

A Study on the Structural Design and Structural Analysis for Small Yacht

The scantling and structural design work is done during the initial stage in yacht design. This paper studies a procedure of the structural design for yacht with an illustrative design. Scantling of structural members and loads are defined based on the rules suggested by ISO(International Standard O...

A Functional Review and Prototype for Ship PDM implementation

The current challenge with which most shipyards are faced is to reduce the design time and the time-to-delivery benefits of new information technologies such as ERP, APS, and SCM system. These technologies should integrate the information that flows in the enterprise wide activities. First of all we should maintain control of ship design and product data such as bill of material, product structure, drawing, 30 modeling and manufacturing information for the integration. The product data management (POM) system copes with these requirements. All the product data is stored in POM database and vaults in a structured manner and all the changes of product data are monitored, controlled and recorded. This study discusses how POM system can be implemented in shipyard. The procedure is surveyed to apply a POM system for the ship design data management. This study also presents several examples in order to make a practical guidance for ship POM implementation. Proposed studies can be useful for shipyards planning to adopt POM systems in enterprise wide manner.

A business model-based design of a damage control support system for naval ships

When a ship is hit, cutting-edge damage control systems are used to mitigate the problem, but most onboard recovery activities are carried out by the crew. Therefore, the key to damage control rests with the activity of the crew. To design a new damage control support system, a reasonable design process is required. Systems engineering has been applied in the development of many defense systems, and the effectiveness of its contribution has been proven. However, the success of a project also depends on other factors, such as “user involvement,” “concern of executive,” and “expectation”; contemporary systems engineering process do not consider these factors enough. This paper uses a systems engineering approach to guide the development of a new business model-based design method. To guarantee success of the project in the design phase, a business model is used as the “system analysis and control” tool. A new system for damage control support is developed using the proposed design process. The proposed design process makes it possible to design a reasonable system for damage control support with a minimal number of physical components, at affordable cost. The method also makes it possible to validate a given systems effectiveness and technological feasibility.

A framework of Plant Simulation for a Construction of a Digital Shipyard

Recently, world leading companies on manufacturing field are trying to adopt a PLM methodology, which is a new production paradigm, for a survival and strengthening the competitiveness. Some projects for a digital shipyard including a methodology of a digital simulation framework are going on by Seoul national university and Samsung heavy industry. A Database methodology for a scheduling data, an interfacing methodology for a simulation input and output, and a synchronized simulation related methodology are required for enhancing the value of the digital simulation for shipbuilding. In this paper, such a methodologies and a related case study for a fabrication factory and an assembly factory are presented.⨋㴀Ԁ歳湶攛i閜귬蚌賬Ꞅ駪뎵駭验

Three Dimensional Thermal-Elastic Plastic Analysis of GMAW Considering the Melting of Weld Bead

Welding is essential in ship production since welding is very popular method for joining two or more metals. However, welding causes residual stress and distortion and these give a bad influence to the structure strength and assembly of ship blocks. Therefore, prediction and treatment of residual stress and distortion is a key to accuracy control in shipyard. In this paper, a computational procedure, based on thermal-elastic-plastic 3-dimensional FEA, has been suggested to simulate butt and fillet welding process. In the simulation process, temperature distribution at each time step is obtained by heat transfer analysis and then thermal deformation analysis is done with obtained temperature distributions to find the residual stress and distortion. In heat transfer analysis, enthalpy method is used to realize phase change at melting temperature. Also element birth and death method is used to simulate adding of weld metal in both heat transfer analysis and thermal elastic plastic analysis. The proposed procedure is verified by related researches and the results show good agreement with those of related researches.