交变载荷

The double effect of high-speed multicycle impact,speed and load fluctu ant characteristics is the key factors influencing on wear resistance and multicycle impact resistance for th e high-speed automotive chain.

高速多冲以及速度与载荷交变特性的双重效应，是影响汽车用高速滚子链耐磨性和多冲抗力的关键因素。

It is considered that fatigue crack is early produced on drill pipes, because the vibration load of drilling tools in air drilling is more severe than in mud drilling. Fatigue cracks easily occur under alternating vibration. Because the current wellhead detecting instruments can not be used to reflect the change of pump pressure produced after drill pipe piercement timely and accurately, effective measures can not be taken in time to prevent the expansion of fatigue cracks. As a result, drill pipe fracture accidents occur.

失效分析表明，钻杆属于早期疲劳断裂，断裂主要原因是在空气钻井过程中钻具受到的震动载荷远大于钻井液钻井过程中的震动载荷，在交变的震动载荷作用下，钻具容易产生疲劳裂纹；由于现有的井口检测仪表不能精确及时反映钻杆刺穿之后产生的泵压变化，无法及时采取预防措施，疲劳裂纹不断扩展，最终导致了钻杆断裂失效。

According to the clear water experiment, aeration performance of the new equipment is good with high total oxygen transfer coefficient and oxygen utilization ratio.

曝气设备的动力效率在叶轮转速为120rpm～150rpm时取得最大值，此时氧利用率和充氧能力也具有较高值。

The environmental stability of that world - including its crushing pressures and icy darkness - means that some of its most famous inhabitants have survived for eons as evolutionary throwbacks, their bodies undergoing little change.

稳定的海底环境─包括能把人压扁的压力和冰冷的黑暗─意谓海底某些最知名的栖居生物已以演化返祖的样态活了万世，形体几无变化。