fatigue fracture propagation

Fracture lines start from the outside and spread over the whole cross section, particularly starting in the fillet area and very often after a fatigue crack propagation.

断裂面从轴承部位外部开始延伸到整个截面。典型的是从圆弧部开始，常常会由于疲劳而产生的裂纹的扩展后引起的。

The primary failure model is fatigue fracture that is always resulted by the crack initiation and propagation.

疲劳断裂是气门弹簧失效的主要模式，它是疲劳裂纹萌生及其扩展的结果。

The mechanical properties of the butt welded joints have been evaluated according to the impulsive and fracture toughness as well as the rate and threshold values of fatigue crack propagation.

根据试验测定的焊缝各区冲击韧性、断裂韧性、疲劳裂纹扩展速率和疲劳裂纹扩展门槛值，对焊缝力学性能作出综合评价。