We found that the reasons of the fracture were the force on the end coil which was bigger than others and the rubbing wear at the end coils contacting part.

• 利用扫描电镜观察其断口形貌,得出结论,造成弹簧端圈断裂原因有二,其一是弹簧端圈受力较大,其二是端圈接触部位的摩擦磨损引起的。