轴承强化研磨加工时间对沟道表面残余压应力的影响

通过试验探讨了在轴承强化研磨加工中加工时间对套圈沟道表面残余压应力的影响。试验结果表明,加工时间对残余压应力影响反应很快,开始加工时间区段,随着加工时间的增加,残余压应力增大,随着时间的推移,增加速度变慢并逐渐趋于稳定。

强烈淬火对20CrMnTi钢力学性能的影响

对20CrMnTi钢进行强烈淬火试验,研究了强烈淬火对其力学性能的影响。结果表明,分别经CaCl2水溶液、液氮及二者分级淬火数秒均获得残余压应力,且经CaCl2水溶液×1 s+液氮×4 s分级淬火获得抗拉强度、冲击韧度、表面硬度及表面残余压应力的最大值,此工艺为较优工艺。抗拉强度与表面残余压应力线性相关。

陶瓷喷丸强化对TC4-DT钛合金疲劳性能的影响

为了探讨陶瓷丸喷丸强化对TC4-DT钛合金疲劳行为的影响,对TC4-DT钛合金进行了铸钢喷丸强化和陶瓷喷丸强化,采用表面轮廓仪、扫描电子显微镜、旋转弯曲疲劳、轴向疲劳等研究了2种喷丸介质对TC4-DT钛合金表面粗糙度、表面形貌、表面残余压应力、疲劳寿命、疲劳强度的影响。结果表明:陶瓷丸喷丸对TC4-DT钛合金疲劳极限影响不大,陶瓷丸喷丸后表面形貌和粗糙度明显优于铸钢丸喷丸表面,陶瓷丸喷丸强化效果优于铸钢丸喷丸,可提高疲劳寿命达20倍以上。对于薄壁零件喷丸强化,陶瓷喷丸强度不宜超过0.15 A,喷丸强度过高,强化效果不佳。

Influence of residual surface stress on the fracture of nanoscale piezoelectric materials with conducting cracks

In this paper,we analyze the stress and electric field intensity factors affected by residual surface stress for conducting cracks in piezoelectric nanomaterials.The problem is reduced to a system of non-linear singular integral equations,whose solution is determined by iteration technique.Numerical results indicate that the residual surface stress can significantly alter the crack tip fields at nanometer length scales.Due to the residual surface stress,281he electric field can produce stress around crack tip.This suggests a strong electromechanical coupling crack tip field for nanoscale piezoelectric materials.Such a finding is considerably different from the classical fracture mechanics results.A transit electric field to stress load ratio is identified,for which influences of residual surface stresses vanish.The research is useful for the applications of nanoscale piezoelectric devices.