To investigate the effect of automotive millimeter-wave radar radome matenvls on millimeter-wave transmittance performance, this paper inelaborates the intrinsic relationship between material transmission loss and electromagnetic parameters, and tests the electromagnetic parameters and transmission loss of several commonly used radar cover plastics, as well as the transmission loss of different Polypropylene (PP) material thicknesses. The results indicate that low polarity materials generally have lower dielectric constants and dielectric losses. The transmission loss of millimeter waves in bumpers exhibits a periodic relationship with wall thickness, and the transmission loss is minimal when the thickness is an integer multiple of half a wavelength. Furthermore, through analysis of the transmission loss of materials with different paint coatings and metal coatings, it is found that aluminum powder and pearlescent powder in paint components have a significant negative impact on the transmission performance of millimeter waves. Physical Vapor Deposition (PVD) aluminum plating is not suitable for Adaptive Cruise Control(ACC) vehicle logos, while appropriate film thickness PVD indium plating has minimal interference with millimeter waves and meets the transmission requirements.

In response to the problem of insufficient fatigue strength of the shear edge of the 700 MPa level frame longitudinal beam, optical microscopy, scanning electron microscopy and fatigue testing machine are used to evaluate the properties of the shear edge under existing process conditions in this paper. The research results indicate that the burrs on the shear edge of the 700 MPa level frame longitudinal beam are effectively removed by rolling deburring process. However, due to the folding caused by burr lodging, the fatigue strength of the shear edge is only 206 MPa, and the fatigue failure originates from the folding root at the rolling edge of the tear band side. To improve the fatigue strength of the shear edge in further, the parameters of the shear edge rolling process are analyzed and optimized combined with CAE analysis. The results show that in order to form a large residual compressive stress on the shear edge, the optimal angle between the roller working surface and the hot-rolled plate surface is 30°~45°, with a rolling depth of 0.5~1.0 mm. The chamfered surface formed by rolling the upper and lower edges of the shear edge is smooth and flat by using optimized rolling process. The hot-rolled surface of the original plate has no obvious protrusions, and there is no outward protrusion in the middle of the cross-sectional profile of the shear edge. Finally, the fatigue strength of the shear edge reaches 263~270 MPa.

To address the issue of excessive engine exhaust smoke and insufficient power occurring after 275 km of operation in a certain engine turbocharger, a systematic analysis of the failed turbine shaft is conducted using methods such as macroscopic inspection, scanning electron microscopy analysis, metallographic observation, and hardness testing. The results indicate that the turbine shaft fracture is a low-stress, high-cycle fatigue failure under significant stress concentration. The fracture originated from a severely scratched area at the fillet caused by poor grinding processing. The root cause is identified as poor lubrication leading to dry friction between the shaft and bearing, subjecting the bearing to abnormal alternating stress. The study concludes that although the machining defect created a stress concentration source, the abnormal operating condition (dry friction caused by oil shortage) is the primary factor triggering this premature fracture.

To study the testing methods and issue diagnosis of high-voltage systems in new energy vehicles, this paper examines high-voltage electrical safety from two levels: equipment-level and vehicle-level and analyzes existing the high-voltage electrical safety regulations, standards, and the current technological status of new energy vehicles. The study also investigates the high-voltage insulation condition of new energy vehicles and corresponding protective measures, including the principles and testing methods of high-voltage insulation systems and monitoring systems. Finally, comprehensive solution for high-voltage electrical safety analysis, protection, design, and testing has been developed. This solution can perform exhaustive verification across various operating scenarios of new energy vehicles, enabling precise identification of system safety threshold violations and validation of operational safety, thereby simplifying the difficulty of issue diagnosis.

To improve the reliability of hemming processes for automotive closure panels and prevent appearance defects, the hemming processes of the hood, front door, and rear door assemblies are analyzed during the process design phase using AutoForm software and CAE numerical simulation technology. 2 rounds of hemming simulation and 1 round of simulation validation are conducted, yielding the following results: The first simulation identifies the location, extent, and severity of wrinkling in the 3 assemblies. The second simulation addresses the wrinkling defects by adjusting roller parameters and flange lengths, achieving a 100% qualification rate for both gap and flushness simulations across all 3 assemblies, with the rear door gap qualification rate increasing by 27.78 percentage points. Validation results show strong correspondence between the measured data and the first simulation: the hood gap control qualification rate is 86.21%, while the front and rear door assemblies achieved 100% gap control qualification. The overall consistency between measured and simulation results exceed 95%. The flushness qualification rates for the hood, front door, and rear door are 67.24%, 67.86%, and 97.22%, respectively. However, the consistency between measured and simulation results for the hood and front door is below 81%, primarily due to the absence of chain analysis and the inability of ideal numerical simulations to account for stamping stress and forming tolerances.

To quantitatively analyze the impact of electrode tip diameter on nugget diameter, resistance spot welding experiments and finite element analysis are conducted on hot-stamped steel using electrode tips with diameters of 6 mm and 8 mm. The welding currents required to obtain the same nugget diameter with electrode tips of 6 mm and 8 mm diameter are investigated. The results show that with the increase of welding current, the influence of electrode tip on the nugget diameter of resistance spot welding is gradually reduced without splash; When splash occurs, the electrode tip of 8mm diameter will obtain a larger nugget diameter. For 1.6 mm HQAS1500H+1.6 mm HQAS1500H plate group lapping form, the resistance spot welding process parameters can be set as 3.43 kN/420 ms/7 kA~3.43 kN/420 ms/8 kA. Within the common production welding current range, the deviation between the actual nugget diameter and the finite element simulation nugget diameter is less than 10%.

To study the applicability and advantages and disadvantages of recycled plastics in the automotive field, bumpers skins are made from recycled and virgin polypropylene plastics (RPP and VPP), and the low-speed collision performance of the 2 materials'bumpers is compared and analyzed using a pendulum impact system. The results show that no fracture occurred after the test of the 2 material bumpers under different impact strengths, but the width of the RPP bumper abrasion is larger than that of the VPP, and the visual performance is not excellent. The impact force generated by the collision under the same load was less than that of the VPP, but the impact time is reversed, indicating that the impact acceleration of the RPP bumper is more modest, which is more advantageous in pedestrian protection. In addition, the mechanical properties of materials are analyzed in order to investigate the reasons for the variation in test. The yield elongation of the VPP material is lower than that of the RPP (35%) and the impact strength and energy absorption are slightly great. This allows the RPP bumper skin to generate the same deformation with less force (less impact acceleration). The performance of RPP bumpers is close VPP due to the advantage of additives of RPP and the greater melt fluidity.

Transmission noise directly influences the comfort of the entire vehicle. This paper reviews the existing transmission noise control techniques, and introduces the mechanism and transmission path of high-frequency whine noise, mid-frequency clashing noise and low-frequency vibration noise according to the noise frequency characteristics. Research shows that optimizing the transmission housing structure and applying sound-absorbing materials can reduce the radiation of whine noise. Micro-texturing of gears is efficient and cost-effective for improving gear whine noise, and is expected to be a future research hotspot. Adjusting torsional characteristic parameters and reasonably increasing the drag torque of idler gears can effectively suppress clashing noise. The influence of temperature on gear deformation needs to be considered in future studies. The dual-mass flywheel performs well in controlling engine speed fluctuations, and future research can focus on improving the design of the dual-mass flywheel and optimizing the engine calibration program. Changing the natural frequency of the housing and optimizing gear parameters are effective approaches to reduce vibration noise, however, there are fewer methods controlling oil pump and strap vibration noise, and the influence of lubricating oil on vibration noise should also be considered. The application of future high-efficiency and high-precision transmission noise control technologies will rely on the support of intelligent optimization algorithms.

To reduce the raw material cost of automobile painting shop, this paper proposes a plan to reduce the material consumption of electrophoretic coating, weld seam sealant, lacquer, varnish, polystyrene foam, wax, etc. Taking PVC material consumption reduction of a paint shop as an example, this paper, by analyzing the source of material waste, proposes the methodology of material waste reduction by increasing the utilization of material per bucket in aspects of equipment, process, quality, etc., reducing the manual glue application when changing bucket and reducing glue application amount of robot during production, which reduces the material consumption per vehicle significantly and reduces material cost.

In order to realize the lightweight of auto body, the traditional one-piece BIW dashboard panel is designed into two parts (the upper one and the lower one) with different thickness. According to the typical features of the front dashboard panel, namely the arch shape of the evacuation area of the wheel cover, this paper proposes shallow drawing plus reshaping to simplify stamping process and greatly improve material utilization rate. In order to address the issues of corrugation of dashboard upper panel, insufficient stiffness of single part and poor welding of evacuation area of the wheel cover, the paper verifies the feasibility of shallow drawing plus reshaping through stamping CAE analysis, stamping physical production and welding quality verification. The cost saving advantage of split-type front dashboard panel is confirmed by the cost accounting of the whole process chain (stamping, welding, coating). Finally the low-cost front dashboard panel is put into mass production with shallow drawing plus reshaping process.