The automobile industry, as a representative in pursuing the goals of “emission peak” and “carbon neutrality”, has made low carbon a new industrial practice. With regard to low carbon, the lightweight design proves to be an effective approach to reducing carbon emissions from automobiles. Given the state of research, in which the existing lightweight design schemes of automobiles seldom consider the impact of the lightweight quality on carbon emissions during the whole life cycle of the automobiles, this paper proposes a more comprehensive lightweight design method for automobiles in regard to carbon emissions. First, the finite element method was adopted to analyze the stress, strain and safety factors of the automobile parts based on their stress, so as to identify the positions where the lightweight design was applicable. Subsequently, a lightweight scheme was designed accordingly. Next, the finite element method was re-applied to the parts whose weights had been reduced. In this way, the feasibility of the lightweight scheme was verified. In addition, a method of calculating the carbon emissions produced by changes in the mass, manufacturing processes, application and recycling of automobile parts after the application of the lightweight design was also presented. The method can be used for evaluating the low carbon benefits of the lightweight design scheme. To prove the feasibility of the method, the ZS061750-152101 wheel hub designed and manufactured by Anhui Axle Co., Ltd. was taken as an example for the case analysis. The lightweight design changes three structures of the wheel hub, reducing its weight by 1.4 kg in total. For a single wheel hub, the carbon emissions are reduced by 51.22 kg altogether. That is to say, if the lightweight scheme were to be applied to all the wheels produced by Anhui Axle Co., Ltd. (about 500,000 per year), the carbon emissions from the wheel production, application and recycling could be cut by 2.56 × 10⁷ kg, marking a favorable emission reduction effect. The proposed method can not only provide insight into the lightweight design of automobiles and other equipment against the background of low carbon but also provide a channel for calculating the carbon emission changes in the whole process after the application of the lightweight design.

Addressing the issue of shallow-buried, closely spaced multiple coal seam repeat mining, where the development of overlying rock fractures causes interlayer airflow disturbances, leading to spontaneous combustion hazards in leftover coal and affecting the safe and efficient mining of the working face. Taking Zhangjiamao Coal Mine as the research object, a discrete element numerical model of shallow-buried, closely spaced overlying rock structure particle flow is established to study the development patterns of overlying rock fractures and the evolution of porosity in the working faces during the repeated mining processes of the 2⁻² and 4⁻² coal seams. Based on simulated data, we establish a fitting formula for the relationship between mining height, advance distance, and fracture development height. The research results indicate the following: as the working face continues to advance, the number of fractures in the overlying roof rock increases, and the fracture zones exhibit a horizontal and vertical intersecting distribution pattern, with the range continuously expanding until it extends to the surface, forming a moderately flat subsidence basin in the middle. The porosity range of the roof rock increases progressively with the mining of the working face, and the porosity of the roof rock when mining the lower coal seam is greater than that when mining the upper coal seam. The comparison between the research results and the on-site measured results verified the reliability of the simulation results.