Accounting for hull deflections in the shaft alignment design is deemed an essential task. Conventionally, hull deflections are obtained conducting structural analysis based on Finite Element (FE) modeling of the ship structures with consideration of different vessel loading condition. This is a time consuming and labor intensive task, requiring advanced engineering skills. However, even when skilled engineers are employed, due to complexity of the FE based modeling around the shafting train, the deviation in the outcome of the FE calculations can be substantial when performed by different entities.
In order to avoid inconsistencies with FE modeling, ABS has developed a beam based, 1-D simplified approach to hull deflection calculation. With beam based approach, the hull deflections can be obtained with significantly lesser effort through a simple, fast, and user-friendly environment. The 1-D method is calibrated against full ship FE models and measurements for different types of vessels and different loading conditions.
The new 1-D hull deflection calculation is embedded in the newest version of ABS Shaft Alignment software, which was released in December 2020. The project was led by Martin Petricic, Senior Engineer II, Technology, and Davor Sverko, Technical Advisor, Technology.
Sea News, December 14