The spring can be divided into static spring and dynamic spring according to the running state.
Static spring refers to the spring with limited vibration times in service, such as safety valve spring, spring pad, scale spring, fixed load spring, mechanical spring, watch hairspring, etc.
Dynamic spring refers to the spring whose vibration times are more than 1 × 106, such as engine valve spring, vehicle suspension spring, shock proof spring, coupling spring, elevator buffer spring, etc.
Static spring material selection mainly considers tensile strength and stability, while dynamic spring material selection mainly considers fatigue, relaxation and resonance performance.
According to the load condition, the spring can be divided into three states: light load, general load and heavy load. Light load refers to the spring which bears static stress, low stress and small deformation, such as spring for safety device, spring for vibration absorption, etc. The designed service life is 103 ~ 104 times.
The general load refers to the common spring which has a design life of 105 ~ 106 times and is used under the condition of vibration frequency of 300 times / min. The lower the load stress, the longer the life.
Heavy load refers to the spring which works for a long time and vibrates frequently. Such as valve spring, air hammer, press, hydraulic controller spring, its load is high, often less than 10% of the allowable stress, service life is more than 1 × 106 times, usually 107 times.