The damaged propeller shafts caused by the fatigue failure will be repaired by shield metal arc welding process. The service life dependeds on fatigue endurance limit of welding surface. This study was aimed to compare the fatigue resistance of two types of hard facing electrodes using the same arc welding repair process. The investigation of fatigue stress at 517 MPa in failure criteria showed that the propeller shafts repair by Flux core arc welding Process using electrode grade E110T5-K4H4 provided the approximate same service life as that using electrode grade X111-T5-K4 but lowered the repair costs up to thirty-five bath per kilogram electrode. As a result the total maintenance cost decrease 68250 baht per year.

This study evaluates the fatigue life of a closed-loop oscillating heat-pipe with check valves (CLOHP/CV). The method was predicting the fatigue life of the copper tube to apply for the CLOHP/CV. The fatigue test was carried out by using the specimens made of copper tube (C1220) at the temperature of 293 (room temperature) 473 and 573 K. The three types of hourglass shaped specimen included uniform type one-wave type and two-wave type specimens. It was found that the effect was a direct extension of material structures of specimen and hourglass shaped. It can be said that the number of cycles to failure (Nf) of the two-wave type specimen hourglass shaped specimen was rather sensitive to fatigue motion during testing and the temperature of 573 K has the greatest failure impact.