In order to address the issue of failure fracture of balance suspension leaf spring seat of engineering vehicle, this paper analyzed the balance suspension leaf spring seat by process analysis, fracture analysis, metallographic examination, strength test, hardness test and material fatigue limit testing. The results show that the material used in the balance suspension leaf spring seat meets the standard requirements, and the failure modes include multi-source high stress and low cycle bending fatigue cracking, the crack originates from the rounded root between the balance suspension leaf spring seat and the U-bolt, which is thick and easy to produce defects like shrinkage and porosity in the production process. In the structure, this position is the balance suspension leaf spring seat under the greatest stress position and a dangerous section of the part.

When the exhaust pipe is welded with the flange, the welding deformation of the flange affects the tightness of the exhaust pipe assembly. In order to avoid excessive welding deformation of flange during manufacturing, the FEA model was established with the moving Gaussian heat source to simulate flange welding process. After analyzing and comparing the temperature field, stress and strain results of flanges under different constraint conditions and different welding parameters, the solution that can effectively reduce the welding deformation of flanges in the production and manufacturing of exhaust pipes was determined. This paper proposed suggestions of welding electric current, welding speed and heat source radius, which provided theoretical basis for the optimization of welding process of exhaust pipe flange.

In order to achieve traceability management of quality issues in stamping parts, the structure, principles, and advantages and disadvantages of mold mechanical coding technology and equipment laser coding technology were analyzed. Mechanical coding is installed on the mold, and online replacement results in production line shutdown. The coding time is accurate to weeks; Laser coding is integrated with the production line, without the need for stopping the production line to change labels, and the coding time is accurate to the parts.Different coding methods were selected according to different application conditions to meet the precise quality traceability control of stamping parts from single batch to single piece. At the same time, through digital means, various fields of coding information are connected, achieving tracking from stamping profession to vehicle quality traceability information binding.

In order to improve the service life of spot welding electrodes, TiB2-reinforced copper matrix composites were prepared using a multi-step method. The physical phase and microscopic morphology of the TiB2-reinforced copper matrix composites prepared by the multi-step method were analyzed using X-ray diffraction (XRD), metallographic microscopy and scanning electron microscopy (SEM) characterization. By measuring the mechanical property indexes of the composites, it was found that the copper matrix composites prepared by the multi-step preparation had better comprehensive mechanical properties. The copper matrix composites prepared by the multi-step method were processed into spot welding electrodes, its life test results were the highest compared with other comparison samples, with a life time of 1 500 solder joints, which was 2.6 times longer than the life time of common chromium zirconium copper spot welding electrodes.

To reduce the adverse effect of aluminum silicon coating layer on the surface of steel plate on laser joint, laser wire filler welding joint with aluminum mass fraction less than 1% in weld was obtained by using thin-coated hot-formed steel material and laser wire filler welding technology. The macro and microstructure of the welded joint were analyzed, it was found that the welded joint was replaced by the whole martensite structure after hot forming, which avoided the softening phenomenon. The mechanical property analysis shows that the tensile strength of the sample increases from about 570 MPa to about 1 500 MPa after hot forming, and the weak link of the joint is located in the base material. High speed tensile has no adverse effect on the tensile strength of the joint, but the elongation at break is affected greatly.

For the forward design of extruded aluminum door sill section in side pole crash condition, this paper analyzed the pros and cons of the Equivalent Static Load (ESL) based nonlinear optimization and traditional optimization technology. The research indicate that the ESL based nonlinear topology optimization design can obtain a topology path closer to the strategic requirement of crash safety structural deformation in the concept design phase than the traditional linear topology optimization, whereas in the detailed design stage, the ESL based thickness optimization method is better than the traditional approximate model value optimization technology in optimization efficiency and optimization scheme performance.

In order to find the source of formaldehyde emission from automobile parts at high temperature, the research team, by simulating the formaldehyde emission test of the automobile parts under high temperature conditions, used the spectrophotometric method to test 13 kinds of materials commonly used in the car, analyzed the formaldehyde emission amount of different materials under the same conditions, and combined the use of different materials in the car to confirm the main source of formaldehyde emission in the car, so as to provide direction of improvement for auto parts manufacturers.

To deal with the limitation of the existing non-destructive testing technology for the depth of the carburized layer of axle steel, a weak magnetic detection method is proposed. Since the stress concentrates at the junction of the carburized layer and its heart and can’t be eliminated, and then externally show a specific magnetic induction intensity for non. By collecting magnetic field signals from different samples of axle steel and different parts of axle steel, we analyzed the corresponding relationship between magnetic induction intensity amplitude and depth, and constructed a mathematical model for weak magnetic detection. The test results show that: spline outer circle (standard thickness/inspection thickness/absolute error): 3.50 mm/3.57 mm/0.07 mm; rod outer circle: 4.30 mm/4.46 mm/0.16 mm; R-angle: 4.00 mm/3.86 mm/-0.14 mm. The overall relative error of the inspection accuracy is less than 5%, which meets the actual needs of the factory inspection.

For the problems of flange cracking for cross member of steel H420LAD, the stamping simulation of cross member was performed, the scheme was evaluated on type of flange, major and minor stain, paths of strain. The results show that minor stain was the main parameters of parts flanging and cracking, the decrease of minor strain was beneficial to eliminating flange cracking, increasing the plastic strain was the direction of material optimization. 2 schemes to stamp processing were proposed and simulated, the results show that after optimization of the gaps between die and punch, the distances between the blocks for flanging and the punch, the forming safety margin was increased from 0% to 4.49%, the edge quality of part was improved slightly. The optimization of blank was carried out, the process of pre-flanging was changed to drawing, process of trimming was added, the forming safety margin was increased from 0% to 16.44%, and the qualified rate of the parts is 100%.

At present, most of the powertrains of medium and large luxury cars adopt the form of longitudinal engine rear-drive. Based on the assembly of a luxury brand vertical engine structure in the engine pre-assembly line of the assembly workshop, a specially designed engine carrier lifting fixture was used to realize the process installation of the parts. The lifting fixture was used to simultaneously lift the engine and transmission as well as the front axle assembly on the pre-assembly line, and automatically move the suspended integrated lifting fixture assembly and the workpiece on the pre-assembly line by carrying lifting fixture, thus completing the process installation of the parts. This paper discussed the application advantages and functional characteristics of this engine pre-assembly line process planning scheme and engine carrier lifting fixture for simultaneous suspension of multiple large mass parts, then introduced cases of lifting fixuture optimization.