通过对新、旧发动机缸盖取样进行疲劳试验,对比了其S-N曲线，结果发现：应力幅较大时,新、旧缸盖材料的疲劳寿命相差明显;应力幅较小时,新、旧缸盖材料的疲劳寿命相差不大,表明旧发动机缸盖材料的损伤程度随着应力幅的增加而增大。因此当发动机经过再制造后,有可能因为累积损伤的原因存在安全隐患。

By means of fatigue test,the S-N curves of new and used engine cylinder heads were compared. It was found that the fatigue lives had an obvious contrast between new and used materials in the case of a large stress amplitude,while in a small stress amplitude,the difference between them was very little. It can be concluded that the damage degree of engine cylinder head after refabrication will become serious along with the increase of stress amplitude. In a word,as the result of damage accumulation,the engine may have a hidden trouble of safety after refabrication.