振动时效机理及其对疲劳寿命的影响分析

运用细观力学的方法分析位错及其塞积群的应力场,在此基础上研究外力作用下塞积的开通与残余应力释放的关系,得出了使内部残余应力得到宏观释放的激振动应力条件为残余应力和激振动应力之和应大于材料的屈服应力。同时从微观角度揭示了振动时效时,工件内部位错密度增大、位错分布更趋均匀的过程,并得出适当的振动应力可以使工件的疲劳寿命提高的结论。最后用实验验证了振动对位错的影响。

Vibration Stress Relief Mechanism and Its Impact on Fatigue Life

Based on micro-mechanics, the stress of dislocation and dislocation stopper was analyzed, and the relationship between dislocation stopper shift and residual stress relief acted upon by the external force has been studied. The necessary condition for macro-relieving for the internal residual stress was obtained. Meanwhile, from the micro point of view, the increase in dislocation density and the uniformity in dislocation distribution in the internal workpiece in the process of vibration stress relief was also discussed and the conclusion was drawn that proper vibration stress could increase the fatigue life of the workpiece. Finally the effect of vibration upon dislocation was verified through the experiment.