Experimental study on the failure of tangential anti-loose dowel of ship hydraulic fluid tubing in alternating torque and vibration environment

Abstract

The internal hydraulic fluid tubing in central shaft is a critical part of pitch adjusting paddle in the ship propulsion system. The failure of screw pairs of internal hydraulic fluid tubing will result in a loss of propulsion. This real accident has happened on a ship. In order to determine the reason for the tangential anti-loose dowel falling out from the screw pairs, 380.5h and 147h alternating torque and vibration environment tests are completed on two samples with difference of manufacturing processing. The result shows that alternating torque and vibration combined stress is the synthesis stress for the dowel falling out from dowel hole. The basic reason is the larger fit clearance between dowel and dowel hole. This clearance is suggested to be manufactured below 0.2∽0.3mm, and the value of diameter for piercing outside the dowel hole should be greater than 1.95mm.