【摘要】 考察了国产 18MnHP钢材预先塑性应变对疲劳裂纹扩展的影响 ,研究了国产 18MnHP钢材和国产LY11—CZ铝合金单峰超载所引起的疲劳裂纹扩展的延迟阻碍现象。通过实验结果分析可知 :①单调预拉塑性应变对疲劳裂纹扩展速率无影响 ;②预先拉压循环塑性应变导致对疲劳裂纹扩展速率的提高 ,是由循环塑性应变造成损伤所引起的 ;③超载后裂尖前沿材料的应变硬化不是导致延迟阻碍现象产生的原因 ,而宜用裂纹闭合效应来解释延迟阻碍现象。更多还原

【Abstract】 The influence of pre-plastic strain on the fatigue crack growth in 18MnHP steel and the retardation phenomenon induced by occasional overloading in 18MnHP steel and LY11-CZ aluminium are studied experimentally.It is shown that, under the condition of the present experiments:①the fatigue crack growth rate is not effected by the pre-plastic tensile strain; ②the crack growth is accelerated by the pre-cyclic alternative plasic strain and this may be referred to the damages accumulated due to the pre-cyclic strain;③the retardation phenomenon following the occasional overloading can not be explained as a result of strain hardening of the material in front of the crack tip and the author intends to refer the retardation phenomenon to the closure effect of the fatigue crack.更多还原