Experimental Study on the Effect of Hull Deformation on the Relative Attitude between Shaft and Bearing

Abstract

The unclear change laws of bearing offset and rotation, both of which influence the condition of shaft alignment during hull deformation, make it difficult to optimize shafting design. In this paper, an integrated hull-bearing-shaft model is designed and built for a cantilever beam loading test. Displacement sensors are utilized to determine the change in displacement of the hull, bearings, and shaft. The pressure distribution at the bow and stern ends of the bearing is measured using a new type of thin-film pressure sensor. The test results show that the rotation angle of the shaft and bearing varied differentially during hull deformation, and the magnitude of the shaft-bearing angle was comparable to the rotation angle. The measured rotation angles of the front and rear ends of the stern tube bearings are opposite to the theoretical value of a cantilever beam, indicating that the stern tube has a non-negligible effect on local deformation, and it is recommended to measure the bearings directly as opposed to the alternative structure to obtain the rotation. The change pattern of the shaft and bearing attitude does not change with the different initial state of the shaft, which indicates that the initial error of installation will be retained during the hull deformation process. The change pattern of the shaft and bearing attitude is unaffected by the initial state of the shaft, indicating that the initial installation error will persist during hull deformation. In some instances, the bearing reaction force remained unchanged, but the shaft-bearing angle and bearing pressure altered, indicating that the bearing condition cannot be determined solely by the bearing reaction force. The results of bearing pressure and the shaft-bearing angle can be compared, indicating that the thin-film pressure sensor can be used to determine the status of the shaft-bearing angle, particularly during the installation phase.

Keywords

• hull deformation
• shaft alignment
• cantilever model tests
• bearing offset
• rotation angle
• bearing pressure