Digital Research On The Shafting Alignment

Shafting is the propulsion source for vessel. So it is one of the key parts whose stability determines whether the vessel operates normally. For large vessel, rational alignment is commonly taken to ensure the shafting works. Rational alignment adjusts the heights of the bearings before chocking in order to meet the requirements, which leads to two main tasks:how to adjust the heights and how to conform whether the heights reach the layout. Most of the shafting research focus on the bearing loads calculation. And in China, the research results short of the test which taken on the vessel. So, large quantities of the domestic shipyards depend on experienced workers to do the shafting alignment and the load measurement.With intensified shipbuilding market competition, the domestic shipyard expects to develop digitized shafting alignment which shorten the time and improve the precision of the construction to enhance the competitiveness. To satisfy the practical demand, this article arranged related technical theory, and put forward the corresponding solution:Based on Timoshenko Beam, this article built the Finite Element Method (FEM) model. Listed the idealization during simulation and explained the realistic foundation of the idealization. Then combed the various kinds of optimization algorithm using in shafting alignment, this article proposed quadratic programming to do the shafting alignment calculation which improved the computational efficiency as well as the feasibility of the result. For bearing load measurement, this article selected Bearing Jacking and strain measurement. The data acquisition processes of the measurements are different. The measurement data of bearing jacking is dynamic while strain measurement is static. So, the digitization for bearing jacking focused on redeveloping the data acquisition unit (DAU) of the sensor which recorded the data automatically. For strain measurement, the general calculation module was written to shorten the calculation time.According to the above scheme, this article accomplished the software and hardware modules and achieved the digitized shafting alignment. Put them into test on vessel, defects and loopholes were found. After correction and remedy, there came the finished system. This system reached the leading domestic level and filled the domestic blank in this field. The research results not only promoted technological advances for the shipyard, but also contained a large economic benefit.