Taking 22CrMo material passive bevel gear of drive axle as the research object, this paper studies the influence of material composition fluctuation on carburizing and quenching characteristics of bevel gear by finite element method. Based on the upper and lower limits of the fluctuation range of the material elements, two groups of material property databases are established using material database software. The heat treatment simulation software is used to establish a model to simulate the carburizing and quenching process of 2 groups of passive bevel gears, and the surface carbon concentration, microstructure evolution and gear deformation of bevel gears are compared and analyzed. The results show that the material composition fluctuation has great influence on the phase structure distribution and gear deformation of 22CrMo bevel gear after quenching, but has little influence on carburizing layer.

This paper analyzes the effects of Sr elements and different heat treatment states on the microstructure, eutectic silicon morphology, mechanical properties, and fracture mode of Al-Si-Mg alloy. The paper also proposes a way to improve the plasticity of Al Si Mg cast alloys by regulating the morphology of eutectic silicon and reducing the number and sizes of hard and brittle phases such as Al (Fe, Mn) Si. The results show that, after Sr modification, the straight sheet eutectic silicon is transformed into fine feather shaped eutectic silicon, the elongation of the aluminum alloy increases by 137% compared to unmodified, while the alloy strength doesn’t improve significantly. After heat treatment, eutectic silicon undergoes melting and spheroidization, changing the fracture mode and mechanical properties of the aluminum alloy. After artificial aging and solid solution treatment, the yield strength and the elongation of the aluminum alloy increase by 73% and 97% respectively compared to the cast state. The quenching temperatures have a significant impact on the mechanical properties of the 2# alloy by T6 treated. When the quenching temperature is 530 ℃, after artificial aging treatment, the tensile and yield strength of the aluminum alloy are increased by 14% and 100% respectively compared to the cast state, and the elongation remains unchanged, demonstrating superior comprehensive mechanical properties.

The shear-tensile properties of bonded joint, self-piercing riveted joint, bolted joint, self-piercing riveted-bonded joint, bolted-bonded joint of HC420/780DP steel and AA6063 extruded aluminum alloy are studied by shear tensile experiments. The results show that self-piercing riveting and bolting can damage the integrity of the plate, and stress concentration occurs in the contact position between the rivets or bolts with the plate during shear tensile process, leading to crack initiation and propagation, and eventually rivet pulling or tearing of AA6063 extrusion aluminum alloy. The structural adhesive increases the stress area of the steel/aluminum joint, and the AA6063 extrusion aluminum alloy with lower strength is broken during shear tensile process. The maximum shear load of bonded joint, self-piercing riveted-bonded joint, bolted-bonded joint are basically the same, but the energy absorption value of self-piercing riveted-bonded joint and bolted-bonded joint increases by 11.8% and 8% respectively compared to adhesive joint. When the steel/aluminum joint is in service under shear tensile load only, it may be considered to use structural adhesive alone for connection without the additional use of self-piercing rivet or bolt.

Considering the application trend of lightweight car body design and the demands for cost reduction, this paper selects metal, CFRP, PC/ABS, PC/PET, PC/PBT, PBT-GF30 as examples, and applies and studies the basic physical properties of sealants and the performance of adhesive strength, substrate matching, aging (thermal aging, damp heat aging, high and low temperature alternation, water resistance, low temperature resistance). The results show that the selected sealant can meet the design requirements except for the poor matching for some plastic substrates (PBT-GF30) at a low temperature of -40 °C. By introducing surface treatment methods such as grinding and plasma, the problem of poor matching of PBT-GF30 in -40 ℃ is solved. Therefore, this paper develops a sealant and process that can adapt to the use of multiple substrates, which can be used in the vehicle design and production.

In order to solve the extensive control of excessive large buffer area in and large welding workshop, large buffer stereoscopic storehouse during different shops transition, simple material flow control inventory quantity, Beijing Benz has developed an intelligent production flow management (PFM) system to assist the BIW to adopt the precise pearl chain order type production control mode, the application of the high flexibility new bin planning (0, X), (1,X) and (1+Y) further improves the workshop process equipment floor area and logistics area, reduces the workshop equipment investment, and reduces the body storage house volume.

Due to the significant difference in the position of the body pivot holes between the new model produced in an assembly workshop and the original one, the existing spreader can’t meet the production needs. Therefore, a solution is proposed to achieve co-production of 2 platform vehicle models by replacing the lifting fulcrum and rear support arm. This solution greatly reduces the modification workload of spreader and the impact on related equipment, shortens the spreader modification cycle, and reduces the cost in integrating new vehicle models. Based on the ANSYS simulation platform, the stiffness and strength analysis of the modified spreader under static and dynamic working conditions are carried out. Online no-load operation testing and vehicle assembly testing are carried out on the spreader samples. The results show that the modified spreader can meet the co-production needs of this dual platform models.

Based on the 25% offset collision condition defined by the China Insurance Research Institute, this paper studies the structural design scheme of the A-pillar of a new energy vehicle. The effect on the crash safety of the basic structure, CBS rubber block reinforced structure, and hot blow forming tube reinforced structure are evaluated and compared. The manufacturing process of CBS rubber block and tube hot blow forming are introduced, and the hot blow forming process is simulated and analyzed. The tooling capital investment and unit cost of the two reinforced structures are further analyzed. The study shows that in the case of achieving an excellent level of small offset collision safety, the 1 500 MPa tube hot blow forming scheme has more advantages than the CBS rubber block scheme in terms of unit cost and light weight.

In order to analyze the influence of gravity deformation on the size pass rate of sheet stampings, Hypermesh and Abaqus were used to construct the nonlinear co-simulation model of gravity deformation of the sunroof cover plate and the tunnel welding assembly. The results show that different placement positions have different abilities to overcome gravity deformation, and the convex placement can improve the ability of parts to overcome gravity deformation. The simulation results verify the feasibility of nonlinear analysis method of gravity deformation to guide the measurement scheme design of sheet stampings of BIW.

In order to solve the cracking problem of automobile wing during road test, this paper analyzes the residual stresses of the Fender produced during the stamping and assembly processes, and studies the influence of residual stress on fatigue failure. The process notch near the fender mounting point is optimized based on the Miner theory to reduce the stress concentration during the assembly process, which effectively improves the fatigue life of the Fender. The problem of fatigue cracking of the Fender is solved without the fatigue simulation based on the road spectrum. This paper provides ideas and theoretical basis for rapid analysis and solution of engineering problems.

Welding tests are carried out on flat copper wires for stator of new energy vehicles’ drive motors by using two processes, ring spot laser welding and TIG welding. Moreover, the welding process and the performance of the joints are investigated and analyzed. The results show that the optimal process of flat copper wire laser welding is 2 500 W for the center core power, 1 500 W for the ring core power, 290 mm/s for the welding speed, and +5 mm for the defocusing amount, and the obtained joints are well formed without weld defects such as pores, etc.; the optimal process parameters of TIG welding are 140 A for the welding current, 150 mm/s for the welding speed, and a small amount of shrinkage holes exists in the obtained joints. The maximum shear strength of the joint obtained by the ring spot laser welding process is 132 MPa, and the maximum hardness of the joint appears in the center of the weld, which is about 140 HV0.2; while the maximum shear strength obtained by TIG welding is 110 MPa, and the maximum hardness of the joint appears in the center of the weld, which is about 128 HV0.2. The welded joints obtained by ring spot laser welding are better than the TIG welded joints in the organization, morphology, and mechanical properties, and they are more suitable for the welding of flat copper wire.