Computer-Aided Alignment of Ship Propulsion Shafts by Strain-Gage Methods

A generalized procedure to compute all bearing reactions using finite-element and strain-gage techniques is explained. A computational algorithm for computing optimum bearing offsets both for new design as well as existing ships to get optimum bearing reactions is presented along with a numerical example. Advantages of the strain-gage method over other methods in working out a proper shaft alignment are described. A procedure to estimate the existing reactions in all bearings with the aid of strain gages, even for the case of three inaccessible bearings, is explained. By this feature, the strain-gage method is shown to be complete in itself and need not be supplemented by other conventional methods. An ideal architecture for shaft alignment computer software is explained. A technique for online shaft diagnosis in operational conditions using strain gages and onboard computers is shown.