Reverse engineering of ship structures

摘要

During manufacturing, operation and refitting of ships the actual data of the steel structures are needed to control manufacturing processes. Curved surfaces appear as a challenge for measurement technology as well as for data processing, which is a complex and extensive assignment. At Fraunhofer AGP in Rostock techniques for reverse engineering have been developed for more than ten years. The results lead to effective tools for even more shipbuilding tasks. The present article starts with the state of the art in reverse engineering of ship hulls including the mathematical basics of remodeling free-form surfaces using NURBS. Furthermore, the process of curve definition is shown including the evaluation afterwards. This leads to an automated software tool to assess the outcome of surface modelling with the use of different curve analysis models. Some achievements of the work are demonstrated by explaining the main features of two software tools developed in the last years. One is software to calculate the thickness of the filler in order to correct surface imperfections on mega yachts. This reduces cost and time for preparation of paintwork and lowers rework at the hull. The other is a tool to check the geometry of propeller in accordance with ISO 3715 using automated cylinder extraction, which leads to reliable propeller testing procedures. The article provides an overall insight into the progress made in development.