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.

A Ls-dyna software based self-piercing riveting joint simulation method for vehicle crashworthiness analysis of was proposed in this research. Method of solving failure parameters for self-piercing riveting joint was studied based on the combination of finite element analysis and test in different forced states, thus improving simulation calculation efficiency while ensuring simulation accuracy. Firstly, a refined simulation model for riveted joints was established based on experimental design, afterwards, a simplified simulation model was established using *CONSTRAINED_SPR2. Using the extracted values from experimental and refined simulation results as simplified parameter inputs can greatly improve the calculation speed of the vehicle crash crashworthiness model. Through this study, it is shown that this method can achieve a simulation accuracy of over 90% for the peak failure force of the self-piercing riveting joint through calibration with experimental results, and can be applied to crashworthiness analysis of complete vehicle model.

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.

To improve the pickling and passivation process quality of aluminum part before body welding, this paper introduced the pickling and passivation process and common quality problems of aluminum parts before welding, as well as the pickling and passivation process and wastewater treatment technology. The paper provided effective solutions based on practical production. Electrophoresis film quality defects of aluminum parts caused by residual oil were eliminated by optimizing degreasing process. Combined with electrophoresis coating quality and the surface resistance of aluminum, Ti-Zr coating process can’t be found on the surface of aluminum parts before pickling and passivation.

In order to solve the problem that the cross-sectional parameters of AutoForm drawbead could not be directly used in 3D software design, this paper derived solution formula for the cross-sectional parameters of Z-direction drawbead that could be directly used in 3D software, mainly including the distance between the Z-direction elevation on the inflow and outflow sides and the centerline of the drawbead, convex fillets, and concave fillets. The drawbead designed using CATIA software was compared with the drawbead automatically generated by AutoForm, which yielded ideal validation results, with both the width and height errors controlled within the range of 0.05mm, and the draw-in error was controlled in 1 millimeter.

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%.

Static mechanical properties of blind end riveting connection between steel panel and three-dimensional braided carbon fiber panel was studied. The static test of blind end riveting connection combination with two different material thicknesses with the same specimen width and end distance was carried out. Then, the static test was carried out on the blind-end riveting connection combination with the same material thickness with different specimen width and end distance, so as to study the influence of mechanical property, failure mode, specimen width and end distance on its static performance. The research shows that good mechanical properties can be obtained by using blind end rivet to connect steel panel and carbon fiber panel. The failure mode and the maximum failure load of the connection are related to the cutting direction of the three-dimensional braided carbon fiber panel. The specimen width and the end distance have an effect on the failure mode and the maximum failure load of the connection.

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.

After the vehicle abuse road test, the eccentric bolt connecting spring swing arm and subframe rotates mainly because the flange surface of the bolt is convex, the friction on the flange surface is uneven, and the friction coefficient does not meet the standard requirements (standard value: 0.08~016, measured value: head friction coefficient is 0.25~0.27, and the total friction coefficient is 0.18~0.20). The friction surface of flange is line contact. Compared with the surface contact, this kind of bolt has poor anti-loose and anti-rotation performance. Improve the flatness of the bolt flange surface and the uniformity of the friction surface by the following measures: reducing the step height at the hexagon connection of bolts (from 3.2~3.25 mm to 3.1~3.15 mm), increasing the hole diameter of gasket before riveting (from 13.85~13.9 mm to 14.3~14.35 mm) and making the gasket into an opposite angle before riveting (0.5°~1°). The friction coefficient of optimized bolt is qualified, and there is no abnormal rotation failure after the vehicle abuse road test.

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.

Since the line has to be stopped when replacing the electrode tip, the Overall Equipment Effectiveness (OEE) improvement of the automatic production line and manufacturing cost of per vehicle will be affected directly. To address this issue, this paper analyzed the electrode tip replacement time and frequency, used the linear programming model method to build a data replacement analysis model, summarized the risk level of replacement in different scenarios according to practical experience. At the same time, the standardized method of “fixed person, fixed time, fixed station” was implemented, and the final solution was determined after repeated iterative adjustment. After the grouping electrode tip replacement according to this strategy, the replacement frequency and time of electrode tip in the production line area has been reduced, and the overall OEE index has been significantly improved. At the same time, the cost of unit vehicle auxiliary materials was also optimized.

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.