Parametric Ship Hull Design in NX

Abstract

When Wärtsilä Ship Design (WSD) initiates a new ship design project, the work is commenced by constructing initial CAD-data with software products such as AutoCad and NAPA. This data is exported to several other software products to perform smoothing, hydrostatics, hydrodynamics etc. As this initial CAD-data holds low quality, designers and engineers have to devote a substantial amount of time just to prepare it for their respective needs. During the initial design process, changes to the hull design commonly occur multiple times; whose consequence is to add these modifications in the initially used software products. This forces the mentioned designers and engineers to execute another round of preparing the new modified CAD-data. Estimates from WSD states that the total amount of work hours spent on a ship design project currently varies from 30 000 to 50 000 hours. However, WSD are currently planning to implement Siemens NX in their workflow, which ideally would conduce to a vast reduction of total project cost and time, and also render some of the software products currently used as obsolete.Siemens NX is a widely spread and well-known Product Lifecycle Management (PLM) -software that ideally allows a complete data flow, from concept development all the way through production, without having to rely on other software. This thesis presents a method to model and parametrically control the geometry of a ship hull in NX, more specifically of a Platform Supply Vessel (PSV). With this rule based geometry, any potential changes requested can now be done in an instant, including interchangeable ship parts, altogether while maintaining a smooth hull shape. CAD-data exported from NX holds a high quality, and can easily be imported into other software products, so that the succeeding users of the geometry don t have to spend time preparing it for their respective tasks. Understanding ship designers and engineers (user) needs, as well as parametrical design of complex geometry in NX was considered as crucial to achieve the goal of a fully parameterized ship hull. Together with a rule based PSV hull design, this thesis presents a method to equip the model with an intuitive and interactive Graphical User Interface (GUI) using Product Template Studio (PTS), which is an add-on to NX. The resulting GUI provides live hydrostatic output, and allows even inexperienced NX-users to make radical or detailed changes to the hull.WSD has still a long way to go in order to fully implement NX, and to utilize all its possibilities. Still, the result from this study was evaluated by WSD as a valuable addition to their workflow, and they are already planning to test the parameterized hull to design a PSV for a newly signed contract. Furthermore, this work has brought lots of ideas into WSD, and they are considering extending their database to 12-15 rule based hull models, which should cover all of the ship types they produce. Moreover, WSD plans not only to use parametrical design in the starting point of the ship design process, but across the entire chain of the initial design phase.