Mechanical knocking devices or specific knock methods may require lowering the interval threshold to recognize distinct knock events.
机械敲打设备或特定的敲打方法可能会需要降低间隔上限，从而识别出独特的敲打事件。
2
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.