Inverse calculation method of shaft system installation status evaluation based on bending moment influence coefficient

  Objectives  In order to examine the actual status of the ship's propulsion shaft system after installation,

  Methods  a shaft system status inverse calculation method based on bending moment influence coefficient was proposed. The linear relationship between the bending moment and the bearing adjustment of any section of shaft system is derived to calculate bearing offsets and actual load and to inverse the status parameters of shaft system. The characteristics of the bending moment influencing coefficient are studied to establish the shaft system status analysis model which is suitable for the strain test, the strain test points arrangement principles for various types of shaft system are provided, and strain test points optimization method with the aim of reducing the error sensitivity is also proposed. The propulsion shaft system of 38 500 DWT bulk carrier was measured, and the actual installation state of the shaft system was calculated by the proposed method.

  Results  The results show that the bearing loads calculated exactly match the jacked loads and the maximum relative error is 3.14%.

  Conclusions  The correctness and applicability of the method in this paper were verified by the test, and a new method for evaluating the installation status of shaft system is provided.