A fuel supply pipe bracket of a passenger car broke during the whole vehicle's durability test on a rough road. This paper conducts an analysis of the working conditions, material, CAE strength and durability, fracture surface and appearance dimensions of the fuel supply pipe bracket after the test. The material analysis and CAE strength and durability analysis both meet the enterprise standards. The fracture form is determined to be fatigue fracture through fracture surface analysis, and the fracture originated from the R corner at the root of the stamped protrusion on the part surface. The cause of the fracture is determined to be stress concentration caused by the too small R corner during the stamping process through appearance and dimension and CAE analysis. By improving the structure and process parameters of the stamping die, the problem of the too small R corner at the root of the stamped protrusion on the part surface was solved, and the overall feature dimensions of the part were completely consistent with the design model. The improved bracket did not fail during the durability test on a rough road.

To address the forged jourral fracfure of a mcdium-and-heary-duty vehicle, by analyzing the macro and micro morphology of the fracture of the forged journal, it is determined that the source of the crack is located in the center of the neck journal, and the crack spreads from inside to outside. It is judged that the crack is the thermal stress type cracking appearing in the quenching process, and the component segregation of raw materials also plays a certain role in promoting the cracking of the neck journal. The risk of quenching thermal stress cracking caused by excessive neck journal section size is reduced by the process adjustment of the neck position of the forged journal shaft: interior hole first and then tempering treatment, and the influence of the segregation of the core components of the neck journal on cracking is eliminated at the same time. By optimizing and adjusting the production process of forged journal, the risk of quenching crack is reduced and the reliability of the product is improved.

To evaluate the bolt-connection reliability of the integrated aluminum alloy frame for commercial vehicles, this study adopts a systematic method including torque statistics after fatigue test, Brinell hardness test of mounting surfaces, ultimate torque verification test of threaded connection pairs, and anti-loosening test under road load spectrum. The results show that after 1.5×10⁵ cycles of sinusoidal fatigue loading, the residual-torque retention rates of all critical connection points are higher than 70%; the hardness of mounting surfaces ranges from 65 to 115 HBW with uneven distribution and an average value of about 86.5 HBW. The equivalent Brinell hardness is converted from test data obtained using an impact ball with a diameter of 3 mm and an impact energy of 11 mJ, and the connection point of the lower control arm has the lowest hardness; the safety factors for M12~M18 bolt connections are no less than 1.55; under road-load-spectrum loading, the maximum attenuation rates of torque and axial force are 15.3% and 14.9%, respectively.

To address the issues of complex processing, poor weather resistance and easy rotting and deformation of natural wood grain when applied to automotive interiors, this paper systematically studies the core characteristics of three processes in the in-mold decoration (IMD) technology system: in-mold insert injection molding (IML), in-mold transfer (IMR), and insert injection molding (INS). To compare the process compatibility of gravure printing and screen printing in the preparation of wood-like textures, multiple sets of ink-level DOE tests were designed to optimize the visual effect of the texture, and comprehensive performance verification was carried out in accordance with the industry standards of automotive interior parts. The results show that the gravure printing + INS process, with a high tensile rate of 30% to 50%, a surface hardness of 3H+, and excellent weather resistance, has become the optimal choice for preparing complex large curved surfaces of automotive interiors imitating wood textures (without light transmission requirements). Screen printing +IML, the optimized ink hierarchy scheme (DOE 4-4) can achieve a low gloss of 7.3, with excellent matte effect and wood grain layering, making it the optimal process solution for the preparation of wood texture imitation with backlight/working indication. The prepared wood-textured imitation products have passed rigorous tests such as wear resistance, chemical reagent resistance, temperature shock, and damp heat. All performance indicators meet the requirements for automotive interior parts.

To address the height flushness between the long glass fiber-reinforced composite tailgate and side panel after high-temperature exposure, this study combines real-vehicle solar exposure tests, oven aging tests, and finite element analysis. Results indicate that the material creep is the primary cause of the long-term cumulative deformation of the tailgate under high-temperature conditions. Both the optimization of inner-panel reinforcing ribs and the extension of the reinforcement plate can effectively disperse local stresses and suppress creep deformation. A feasibility analysis identifies the reinforcement plate extension as the optimal solution, as it corrects flushness without requiring mold modifications, while offering low cost and rapid implementation. These findings provide valuable insights for the design of similar polymer tailgates.

Aiming at the unsystematic simultaneous engineering analysis for vehicle body final assembly and frequent late design changes and production line modifications in domestic auto enterprises, this paper adopts 3D simulation, process inspection, cost comparison and CAE verification. It analyzes body hanging holes, side skirts, doors, hinges, anti-collision beams and body accessories of a mass-produced vehicle, and proposes solutions to assembly interference, positioning deviation, poor sealing and insufficient operating space. The results show that advanced simultaneous engineering in design phase can avoid production risks, and tooling transformation is more economical. The optimized schemes meet requirements and provide reference for standard analysis and process optimization.

To systematically investigate the quality and reliability verification methodologies for automotive electronics manufacturing processes, this study designs a comprehensive validation framework spanning from discrete components and printed board assemblies to finished modules, in accordance with AEC-Q series standards, ISO/IEC international standards, and mainstream OEM requirements. By integrating quality and reliability requirements directly into the production workflow, an overall verification scheme is established, which explicitly delineates the specific quality and reliability testing items required at each stage of the automotive electronics lifecycle.

To investigate the mechanical properties and fracture behavior of Cold Metal Transfer (CMT) welded joints of die-cast aluminum alloys with different types of welding wires, tensile tests are carried out on two joint configurations, namely butt joint and lap joint. The results show that the wire grade exerts a significant effect on the ultimate tensile force, fracture displacement and fracture absorbed energy of butt welds. Overall, the joints fabricated with ER5356 and ER4047 wires exhibit better performance than those using ER4043 wire. For lap welds, the ultimate tensile force is less sensitive to wire types, while their fracture displacement and maximum fracture absorbed energy present considerable fluctuations.

To systematically investigate the microstructural evolution and mechanical property response of AZ41M magnesium alloy TIG welded joints, alternating-current TIG welding is employed to perform butt welding on AZ41M sheets with 3 mm-diameter AZ81 filler wire. Sound welds with uniform formation, free of apparent surface defects and achieving full penetration, are acquired under optimized process parameters. The microstructure and mechanical properties of the joints are systematically characterized using optical microscopy, room-temperature tensile testing, bending testing, and fatigue testing. The results demonstrate that the welded joint yields a yield strength of 124 MPa, an ultimate tensile strength of 231 MPa, and an elongation of 17.4%, with its strength reaching 89.9% of the base metal. The joint successfully passes 180° face-bend and root-bend tests, indicating favorable ductility. The fatigue limit of the joint is determined as 65.2 MPa. High-cycle fatigue cracks preferentially initiate at or near the specimen surface, and the fatigue crack propagation zone exhibits clear radial striation features.

Capacitor Discharge Welding (CDW) was utilized to perform projection welding between double-layer high-strength hot-formed steel and nuts. An orthogonal experimental design was adopted to systematically investigate the influence of various process parameters on the performance of the projection welding joints, with particular emphasis on nugget size and torque strength. Based on the experimental results, optimal welding parameters were identified through range analysis and comprehensive weighted scoring. The optimal conditions were determined as follows: electrode pressure of 0.3 MPa, welding time of 1.1 s, welding voltage of 320 V, and cooling time of 0.5 s. Under these parameters, the heat-affected zone (HAZ) on the nut side is subdivided into coarse-grain and fine-grain regions, with a microstructure primarily composed of equiaxed ferrite. On the hot-formed steel side, the HAZ consists of a fully quenched zone, a partially quenched zone, and a tempered zone. The fully quenched zone exhibits a coarse lamellar martensitic microstructure, whereas the partially quenched zone features a mixed microstructure comprising martensite, ferrite, and bainite. The tempered zone is predominantly constituted by tempered martensite. Three-dimensional fracture morphology analysis reveals that the fracture mode of the projection welding joint between the upper nut and the hot-formed steel is characterized by a ductile-brittle mixed fracture, while the fracture mode in the lower-layer hot-formed steel joints is primarily brittle in nature.