Based on the above, it puts forward that fatigue is the current object of practice, the training is not effective without fatigue and high-quality training is to create the limit of fatigue.

But steel alloys subjected to cyclic stress levels below their endurance limit rarely fail as a result of fatigue.

The primary cause of breakage is that the dynamic stress exceeded the allowable fatigue limit of the beam, and another cause is that the structure of the beam is unreasonable.