Original scientific paper
THEORETICAL DESIGN STUDY ON SHAFTING ALIGNMENT CALCULATION FOR HIGH SPEED CRAFT
M. H. Chang
; Dept. of Mechanical & Mechatronic, National Taiwan Ocean University
S. H. Juang
; Dept. of Mechanical & Mechatronic, National Taiwan Ocean University
Abstract
The design reliability of the theory applied when calculating the sensitivity of shafting alignment must be determined especially at the initial design stage of shafting arrangement and calculation for the vertical static bearing loads (reaction forces) and pressures in order to obtain positive uniform values, which have to comply with the design requirements of the High Speed Craft Code of Classification Society. Any poor design of shafting arrangement for each vertical static bearing location and/or bearing off-set design value may cause a failed shafting alignment calculation and a non-uniform bearing load or over excessive bearing load and pressure on the propulsion shaft stern tube/strut supporting bearing and possible further damage, for example, excessive wastage and/or crack on a damaged aft shaft strut bearing for a high speed craft.
The objective of this study was to find and verify the design reliability of the applied theoretical method for calculating the suitable design values of each vertical static bearing load and pressure on the propulsion shafting system at the initial design stage of shafting arrangement. The design values for each vertical static bearing load and pressure calculated by theoretical design methodologies of the finite element method (FEM) and the three moment equation method (TMEM) were compared with the shipyard original design values for the same design case of propulsion shafting system. The design deviation of the vertical static bearing from the shipyard original design values was determined in order to decide which design methodology (TMEM or FEM) would be adopted and developed for further numerical algorithm design on shafting alignment optimization. According to the obtained results, both the FEM and the TMEM theoretical design accuracy and reliability were well matched with the shipyard original design values. In addition, the TMEM design results for each static bearing load and pressure proved to be more close to the shipyard original design values.
Keywords
high speed craft; shafting alignment calculation; static bearing load; Finite Element Method (FEM); Three Moment Equation Method (TMEM)
Hrčak ID:
127636
URI
Publication date:
30.9.2014.
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