Research On Ship Structure Modeling Method Based On NX

With the continuous downturn of the world economy,the shipbuilding industry has been severely impacted.In the face of severe market competition,ship designers have to improve the quality and efficiency of ship design as much as possible,shorten the production design cycle and reduce costs.Due to the complex design of ships,the traditional ship design patterns mainly have three problems: 1.the large amount of model data is not easy to manage;2.The structural modeling relies heavily on manual operations,the workload is heavy,and the operation is cumbersome.The efficiency is not high;3.The data between models at each design stage cannot be effectively transmitted,resulting in a large number of repeated modeling,which greatly increase the cycle of ship design.Based on the design habits of ship users and based on integrated and parametric design concepts,the advantages and disadvantages of professional ship design software are analyzed in detail.Based on the understanding of the characteristics of NX data and the modeling process of NX,an effective ship CAD modeling system scheme is proposed for the above problems.In response to the large volume of data in the ship,after extensive data collection to understand the needs of ship users,with the knowledge of learning,combined with NX's own assembly tree and feature tree,three custom data navigation trees these are profile trees,structure trees,and shelf trees are used to managed ship objects hierarchically.In order to solve the tedious manual operation,the NX sketch technology was used to analyze the contour parameters of the ship's components,and a detailed scheme of parameterized modeling was proposed.The parameterized drive of the ship structure and rapid batch creation were realized.For the problem of model data transformation in each design stage,the ship objects such as hull plates,stiffeners,openings,plates,etc.are described by a combination of geometry and data,and expressed using Sheet Body,Curve,Edge,and Face of NX.And material properties,thicknesses,section profiles,etc.are stored in geometry in the form of attributes.In order to ensure the efficient storage of data and solve the problems associated with the updating of components,the ship objects were defined as Panel,Stiffener,Hole,Plate and other ship features using NX's custom feature technology.In this way,the CAD data can be stored in the geometry without loss,and the data can be transmitted to other modules without any conversion,and the CAD model can be repeatedly used that shortens the design cycle and reflects the idea of integrated design.Since the system is based on the secondary development of NX's basic modeling module,in order to highlight the characteristics of ship modeling,the detailed design program of ship lines,hull plates,stiffeners,openings,and plate joints is given based on the classification of ship objects.Finally,taking the 180 000 DWT bulk carrier as an example,this thesis uses the ship's CAD system to design the ship structure and verify the feasibility of the system.At the same time,through the analysis of the modeling time,the efficiency of system modeling was confirmed.