This paper primarily introduces research on the process optimization of steel-aluminum spot welding joint performance and the robust design of welding parameters. Using the Pugh Matrix Analysis, the study compares solutions such as enhanced rivet materials, modified rivet structures, and optimized riveting/spot welding parameters based on factors including joint strength, weld nugget diameter, and cost efficiency, ultimately selecting steel-aluminum spot welding as the optimal strategy. Subsequently, the Taguchi Method and orthogonal experiments are employed to study the influence of welding current, welding pressure, welding time, and electrode cap diameter on joint strength of steel-aluminum spot welding. Finally, a set of optimal welding parameters are selected from the perspective of maximizing shear strength, and steel aluminum spot welding and shear tests are conducted to verify their effectiveness and robustness.

This study takes 40 A·h square-shaped ternary lithium-ion battery as the research object to study their gas generation characteristics after thermal runaway, and uses Accelerating Rate Calorimeter (ARC) and thermal runway gas generation performance test equipment dedicated for large capacity lithium-ion batteries to determine parameters like intensity of pressure and temperatures inside the heat & gas generation unit after thermal runway. Gas production process is introduced based on the widely used thermal runaway heat generation model, providing data support for the establishment of battery thermal runway simulation model with composite gas generation characteristics.

Aim at the undersirable situations occurring during the forming process of plastic hot-air riveting, with the purpose of improving the quality of the rivet head, this paper explores the optimal parameter settings of hot air riveting process to improve the quality of rivet head. By changing the heating time, heating temperature and cylinder pressure of the hot air riveting equipment, the orthogonal test of hot air rivet head quality considering the interaction is performed. The multi-index evaluation process of plastic hot air rivet head is established. TOPSIS method is used to sort out the results of multiple evaluation indexes as the response variables of orthogonal test, and the results of orthogonal test are analyzed by range analysis and variance analysis. The results show that the comprehensive score of the quality of the plastic hot air rivet head is the highest, which is 0.835 7 when the heating time of the hot air riveting equipment is 3 s, heating temperature is 190 ℃ and cylinder pressure is 0.7 MPa.

To reduce production investment, this paper makes feasibility analysis of co-line welding production for heavy-duty trucks and pickup BIW from 4 aspects: platform compatibility (sharing similar modular architectures), process adaptability (employing compatible welding and gluing techniques), production line flexibility (utilizing highly adaptable robotic systems), and logistics management (leveraging diversified efficient logistics) —— all demonstrating strong viability for the co-production approach.

Physical Vapor Deposition (PVD) is an important means of metallization of plastic surface. This paper summarizes the concept and characteristics of PVD technology such as evaporative plating, sputtering plating and ion plating. It also elaborates production process of evaporation and sputtering plating, and compares the advantages and disadvantages with those of plastic plating. Moreover, the application of PVD technology in automotive interior parts and related test and verification projects are introduced and the development trend of PVD is summarized and prospected.

The effects of Sr content on the microstructure, fluidity and mechanical properties of heat-free treatment die-casting aluminum alloy are studied by scanning electron microscopy and electronic tensile testing machine. The results show that with the increase of Sr content, the morphology of eutectic Si phase in die-casting aluminum alloy is refined and modified into fine particles and short bars, the length of the flowing samples of die-casting aluminum alloy liquid increases gradually and the tensile mechanical properties are improved gradually. The optimum Sr content is 0.08% for refining and modification of die-casting aluminum alloy, the length of flowing sample is 879 mm, the tensile strength is 286.2 MPa, and the elongation is 7.9%, the length of flowing sample, tensile strength and elongation of die-casting aluminum alloy are increased by 10.4%, 7.8% and 16.2%, respectively.

The conventional solidification structure of cast pure aluminum is coarse. Applying an ultrasonic field and adding grain refiners during the solidification process can refine the grain size, thereby improving the comprehensive properties of the alloy. This paper studies the effects of the combined treatment of Al-5Ti-1B refiner and ultrasonic field on the solidification process and solidification structure of pure aluminum. The experimental results show that the combined treatment of the ultrasonic field and the refiner can achieve a better grain refinement effect than when they act alone. As the ultrasonic power increases, the grain size gradually decreases, and the number of defects such as cavities and porosity shrinkage also significantly decreases. Ultrasonic field can promote the uniform distribution of heterogeneous phase and alloying elements in the aluminum melt from the refiner, increasing the number of effective heterogeneous nuclei of α-Al. The best combined refinement effect is obtained when the ultrasonic power is 1 000 W. Finally, the combined action mechanism of ultrasonic field and the refiner is discussed, and its microscopic action atomic model is given.

Using the pretreatment method of alkali dissolution acidification and matrix matching method, a working curve is established under the optimal instrument parameters. The contents of impurity elements such as silicon, magnesium, iron, copper, manganese and zinc in aluminum silicon alloy are determined by inductively coupled plasma emission spectrometer. Element interference test and solution acidity test are conducted to determine the detection limits of each element as silicon element 0.009 7%, magnesium element 0.005 3 %, iron element 0.004 4%, copper element 0.001 6%, manganese element 0.000 3%, zinc element 0.000 7%. The repeatability and accuracy of the curve are verified, and the spiked recovery rate of the measured samples is 94% to 106%.

In order to explore the influence of different materials on the performance of automobile steering wheel skeletons, optimize steering wheel lightweight design and Noise, Vibration and Harshness (NVH) performance, this paper systematically analyzes the application of materials such as steel, aluminum alloy, magnesium alloy, Carbon Fiber Reinforced (CFRP) in automobile steering wheel skeletons, compares advantages and disadvantages of those materials in term of performance. In addition, finite element simulation technology is adopted to analyze the influence of different materials on steering wheel skeleton modal frequency. The research results indicate that CFRP features the highest modal frequency, followed by magnesium alloy and aluminum alloy, steel has the lowest modal frequency. Finauy,combined with vehicle types and usage scenarios, differential suggestions on material selection are proposed.

The auxetic honeycomb structures, due to their unique auxetic effect, have considerable potential for application in the field of energy absorption. To further improve their mechanical performance, this paper proposes a novel bio-inspired hierarchical origami auxetic honeycomb structure, combining bio-inspired hierarchical design and origami structure. Numerical simulations are conducted to systematically investigate the crashworthiness of the structures under axial compression. The results show that, compared with the traditional auxetic honeycomb structure, the energy absorption capacity of the novel bio-inspired hierarchical origami auxetic honeycomb structure is significantly enhanced. Moreover, the introduction of the origami design ensures more uniform deformation during the axial crushing process, and effectively reduces or even eliminates the initial peak force of the structures.