EXPRESSIONS OF P-S-N CURVES AND LIFE PREDICTION OF NOTCHED FRICTION WELDED JOINTS

摘要

The expressions of P-S-N curves covering the long life region are obtained from the analysis on the fatigue test results of notched friction welded (FW) joints of #45 carbon steel (Chinese steel) used for half-shaft and cam shaft of car. Then Miner's rule and the expressions of P-S-N are used directly to predict the fatigue life of notched #45 steel FW joints under variable-amplitude loading (VAL) due to the fact that #45 steel belongs to the kind of metal with non-continuous strain-hardening characteristic. The results of the life prediction show that the fatigue life and the critical cumulative fatigue damage of notched #45 steel FW joints under VAL approximately follow a log-normal distribution and it's checked by testing with the notched specimen under one type of programmed block loading.