Light weight: compared with riveted body, the welding body reduces the bolts used in many applications of riveting, and the net weight is lighter than that of riveted body. The body weight of each electric welding metro station is about 500kg lighter than that of riveted body. 2. Body bending rigidity: all electric welding welding body control modules are integrated according to continuous welding. The bending stiffness of the whole vehicle is very large, which is conducive to the overall load-bearing of the body and has good fatigue characteristics. When the body is assembled and welded, the deflection value of the car in aw3 should be set in advance according to the necessity of the bending rigidity of the car body during the calculation. After the body assembly welding, the body will be up warped, and all the car doors can be opened and closed normally. Under aw3 load, the aluminum lantern core pulling rivet does not have negative deflection value. In modular design, the components of the car body are connected by rivets, so the bending stiffness of the whole vehicle is weak. The load is transmitted to another member by bolts, and the key load-bearing method is concentrated on the bottom shelf, and the fatigue characteristics of the whole vehicle are weak. Due to the weak bending rigidity of the whole car body, the pre deflection value of the design scheme can not meet the deflection value required by the machine equipment suspension and aw3 load. Under the aw3 load, the down deflection of the car is more than 10 mm. When the special-shaped rivet is serious, it may damage the normal opening and closing of the car door or the sealing of the car door.