Changxing Mingwang Rubber & Plastic Technologies Co.,Ltd. , https://www.cxmingwang.comFor important springs with many cycles and working under variable stress, the fatigue strength should be further calculated. If the number of cycles of variable stress N ≤ 103, or the stress change range is not large, the static strength calculation should be performed. If the above two situations cannot be clearly distinguished, the calculation of these two strengths should be performed simultaneously.