变幅加载条件下的疲劳寿命预测

在疲劳累积损伤分析的基础上得出了对数累积损伤模型，阐明了变幅加载条件下疲劳损伤的累积特征和寿命预测方法。对数累积损伤模型作为—个失效判据，已在某中口径自动舰炮输弹簧的疲劳寿命预测中得到较满意的应用。研究表明，应力水平改变时，损伤因子D发生不连续变化是导致加载顺序效应的重要原因。

FATIGUE LIFE PREDICTION UNDER CYCLIC STRESS OF VARYING AMPLITUDE

Based on an analysis of cumulative damage resulting from fatigue processes,a logarithmic cumulative damage model has been established,the cumulative damage characteristics and the fatigue life prediction under cyclic stress of varying amplitude are also expounded.Used as a fatigue failure criterion,application of the model to the fatigue life prediction for the feeding spring of a medium calibre automatic naval gun proved to be comparatively satisfactory.Research results indicate that the non-continuous change of the damage factor will take place certainly when the cyclic stress transition from one level to another occurs at a given crack size,and that this change is an important factor of loading sequence effect.