Under normal service and maintenance, the leaf springs will also cause fatigue damage, plastic deformation and elastic drop. This kind of damage is generally slow. If it is not used for a long time, it will be damaged, that is, early damage. (1) cars are often used under overload or partial load. The steel plate spring is designed according to the rated load of the car. If the actual load quality exceeds the rated load of the car or the load bias, the steel plate spring will produce excessive bending stress in the work, which reduces the fatigue strength of the steel plate and causes the early damage of the steel plate spring. Uniform loading according to the regulations will help improve the service life of leaf springs. (2) the speed of the car is too high. Especially when running on a bad road at high speed, the deformation amplitude of the leaf spring will increase and the frequency will increase, leading to the early fatigue damage of the leaf spring. To extend the service life of leaf springs, cars should be driven at an economic speed as far as possible, and should be driven at low speeds on bad roads. (3) emergency braking is often used in automobiles. In emergency braking, the plate springs, especially the front plate springs, bear too much bending and tensile stresses due to the action of the inertia force, and when the stress exceeds the allowable stress, the steel plate will break. Therefore, emergency brake should be used as little as possible.