In order to improve the welding quality of the laser welding process in the processing of polymer materials, this paper explored the principle of laser plastic welding technologies, welding process and its application in the automotive lighting industry. Several influencing factors of laser welding effect were designed and tested to explore its actual influence in production practice. For the defects easily occur in the production process such as virtual welding, over-welding and poor appearance, this paper proposed improvement measures from the aspects of welding materials, power, pressure, speed, welding times, in combination with production practice, which provided a reference for the subsequent application and research of laser plastic welding technology in the automotive lighting industry.

This article studied and analyzed the basic principle of electron beam welding and the main factors affecting welding quality. In combination with the developing project case, this paper, taking the sixth driven gear of a 6-speed manual transmission of a commercial vehicle as the research object, introduced the optimization of welding process parameters and structural design to solve the welding crack problem. The experiment finds that when the welding structure remains unchanged, it is difficult to eliminate welding cracks by changing the process parameters when the welding depth is deeper; Simultaneously optimizing the welding structure and matching it with appropriate welding processes can eliminate welding cracks and meet technical requirements such as welding depth.

In response to the problem of significant fluctuations in the Y-direction dimension of the door, this paper analyzed the influencing factors one by one by using an online measurement system Perceptron, and identified key factors such as the impact of key welding point positions and mismatched under copper welding operation. 2 optimizations were carried out: firstly, by adding a welding plier guiding mechanism to optimize the key welding spot positions; secondly, by adjusting the height of the support block for the under copper welding and optimizing the adhesion between the support surface and the outer panel, the problem of Y-direction dimensional instability of door is solved.

In order to achieve a good fixing effect and reduce the internal stress between fixings, it is necessary to accurately measure the deviation of the stud position after welding on the Body In White (BIW). Based on the ATOS Scanbox (ATOS optical measurement system), this paper investigated the feasibility of direct measurement of studs when using the system for stud position degree measurement, and compared it with 2 commonly used measurement methods (screwing auxiliary cylinder and spraying developer) to study the differences in measurement accuracy between the 3 methods, and analyzed the advantages and disadvantages of different measurement methods from the viewpoint of measurement efficiency and economy.

This paper studied the twinning behavior of AZ31 magnesium alloy in the high cycle fatigue process and the microscopic characteristics of twins, and studied systematically the influence of orientation and fatigue load on twinning in the high cycle fatigue deformation process of magnesium alloy and the role of twins in the fatigue deformation process with the help of metallographic observation, fatigue performance analysis, fracture morphology observation, Transmission Electron Microscope (TEM) and other analysis methods. The results show that twinning could play an important role to the fatigue deformation of magnesium alloy at room temperature, the ratio of twinning varies in different fatigue loading directions, the radio of twinning is the highest for loading perpendicular to the extrusion direction.

Based on the fracture analysis of the screw spring fracture in durability test, the paper determined that the fracture originated from the surface decarburization layer and further analyzed the harmfulness of the surface decarburization layer on the spring life from the perspective of surface microstructure and fatigue crack initiation, the paper concluded that the surface decarburization was the main cause for the early spring fracture. The problem of surface decarburization was solved by improving the heat treatment technology of spiral spring. The durability test of the improved spiral spring was carried out again. The life of the improved spiral spring was greatly improved, the durability test number was increased from failing to meet the technical requirements before the improvement to exceeding 2 times of the technical requirements before the improvement without breaking.

In order to improve manufacturing technology capabilities and production preparation efficiency of production lines in the digital era, this article studied the use of industrial simulation PDPS software for virtual process design of automotive door sealing strip rolling (including simulation of production line design, virtual simulation verification of process and equipment). The results indicate that simulation and validation in the virtual environment can verify the rationality of design schemes in advance, identify design problems, optimize design schemes, shorten installation and debugging time, simulation is an efficient means for factories to achieve rapid intellectualization and digital transformation.

This paper studied iron-ductile metals with incubation/spheroidization treatment and adjustable graphite ball density. Using analytical methods like Scanning Electron Microscopy (SEM), ultrasonic thermal melt loss weight, the paper systematically studied the effects of different nodular graphite densities on the hot melt loss properties of iron-ductile metals. The results show that with the increase of ductile density, the weight of hot melt loss of iron-ductile metal gradually decreases, the molten aluminum corrosion resistance of iron-ductile metal is significantly improved compared with that of H13 steel. After the iron-ductile metal immersion thermal melting experiment, the thickness of the Fe-Al reaction product layer is inversely proportional to the ductile density, the graphite spheres with small spacing and large specific surface area hinder the contact between the molten aluminum and the matrix, diffusion of molten aluminum, thereby inhibiting the corrosion of the matrix by molten aluminum. Iron-ductile metals exhibit better resistance to aluminum melt corrosion.

The continuous improvement of input power and device integration of high-power LED automotive lighting enables the chip junction temperature increase rapidly in a short period of time, reduces its service life and luminous efficiency. Thus improving heat dissipation of LED automotive lighting is a major issue of the present studies. A micro-arc oxidation ceramic coating with a micro-porous structure was prepared on the surface of the aluminum alloy radiator by using micro-arc oxidation surface treatment technology to increase its heat dissipation surface area, the chimney effect produced by the porous structure of the ceramic membrane was used to enhance the convection of heat. This paper utilized ANSYS software to simulate the heat dissipation performance of micro-arc oxidation ceramic coating of high-power LED aluminum alloy radiator, and studied the effect of micro-arc oxidation ceramic coating thickness and porosity on the heat dissipation performance of the radiator. The results show that, when the thickness of the ceramic coating is 28 μm and the porosity is 50.26%, the LED aluminum alloy radiator has the highest thermal conductivity, the smallest thermal resistance value, the best heat dissipation performance.

For the suspected local flexion injury found during vehicle development, the local flexion was confirmed through comparison of critical flexion stress calculations and measurement of normal deformation, identifying the potential risk of local flexion on durability performance. Through stress measurement, the S-N curve at the notch was modified using the Haywood model. Based on the fatigue damage accumulation model that considers loading sequence and interaction, and the dynamic residual S-N curve, the residual lifespan of the component was calculated, and compared with the experimentally measured residual lifespan to verify the feasibility of the method. Based on the above residual lifespan estimation method, a durability target modification method was proposed, pointing out the shortcomings of this method and engineering solutions.