There are two states when the elastic element is under working; one is to work under a certain load and displacement, and keep the load and displacement always unchanged or rarely change, which is called static work; the other is the use of load and displacement. Continuous cycle to and fro alternately. The element is in cyclic operation. Due to different operating conditions, the modes of component damage or failure are also different. The elastic sensitive element of the instrument works within the elastic range, basically in a static working state, and has a long service life, generally reaching tens of thousands to hundreds of thousands of times. The bellows components used in engineering sometimes work in the elastic-plastic range or in the state of alternating stress, and the life span is only hundreds of dry times. The components must be given an allowable working life when they are cyclically working, and the number of cycles, time, and frequency must be specified.
The rated life of the elastic element is the expected service life determined when the element is designed, and it is required that the element is not allowed to fatigue, damage, or fail during this period.