Axial-flux permanent-magnet (AFPM) motors are a kind of important motor with compact structure, high power density and high torque density. In this review, the progress of AFPM motors and their key technologies are analyzed and described, with emphasis on the topological structures, design and optimization methods and control techniques. Based on these analyses, the main findings of the review are the following: (1) the yokeless and segment armature (YASA)-type motors have great potential for development; (2) the multi-objective optimization design theories can be integrated and applied to optimize the design of AFPM motors; and (3) optimal control and sensorless control have important value in improving system reliability and reducing cost. Finally, highlights and prospects are provided for further advancing AFPM motors.

The incentive policies of new energy vehicles substantially promoted the development of the electrical vehicles technology and industry in China. However, the environmental impact of the key technology parameters progress on the battery electrical vehicles (BEV) is uncertain, and the BEV matching different lithium-ion power batteries shows different environmental burdens. This study conducts a life cycle assessment (LCA) of a BEV matching four different power batteries of lithium-ion phosphate (LFP), lithium-ion nickel-cobalt-manganese (NCM), lithium manganese oxide (LMO), and lithium titanate oxide (LTO) batteries. In addition, the 2025 and 2030 prediction analyses of the batteries production and life cycle BEV are conducted with the specially considered change and progress of the power battery energy density, battery manufacturing energy consumption, electricity structure, battery charge efficiency, and vehicle lightweight level. In addition, sensitivity analyses of power battery energy density, battery manufacturing energy consumption, electricity structure, and battery charge efficiency are conducted. The results show that the LFP battery is more environmentally friendly in the global warming potential (GWP) and acidification potential (AP), and the NCM battery is more environmentally friendly in abiotic depletion (fossil) (ADP(f)) and human toxicity potential (HTP). However, the LTO battery shows the highest environmental impact among the four environmental impact categories due to the lower energy density. For life cycle BEV, GWP and ADP(f) of BEV based on LFP, NCM, and LMO are lower than those of internal combustion engine vehicles (ICEV), while AP and HTP of BEV based on the four batteries are higher than those of ICEV. The grave-to-cradle (GTC) phase of vehicle has substantial environmental benefit to reduce the human toxicity emission. With the improvement of the battery density, battery charge efficiency, electricity structure, and glider lightweight level, life cycle BEVs based on the four different batteries show substantial environmental benefits for four environmental impact categories.

The composite T-joint, a typical structural element, is widely used in the fields of aerospace due to their excellent mechanical properties. However, several defects might occur in this material during manufacturing because of the application of co-curing and co-bonding technologies. The existence of the defects results in the reduction in the load bearing capacity, which negatively affects the safety of the structure. In this study, a finite element (FE) model of composite T-joints is established, which is verified by quasi-static tests to investigate the load bearing capacity and failure modes of composite T-joints under bending loadings with different types of defects, including core material defects, radius floating of the fillet, and debonding defects. It is indicated that the failure modes of T-joints with different kinds of defects under bending loadings are similar, i.e., the delamination occurs firstly at the interface between the filling area and the L-rib before expanding to both sides. Meanwhile, the types of defects exert great effects on the load bearing capacity of T-joints, and the debonding defects in the arc area represent the most dangerous one. Furthermore, the orthogonal test method was adopted to analyze the influence of combined defects on the load bearing capacity of T-joints, and the findings reveal that the most sensitive type of defect is the debonding defects, followed by the radius floating of the fillet, and then core material defects. This result indicates that combined defects have a coupling effect on the load bearing capacity of composite T-joints. This study provides theoretical guidance and technical support for the repair of the defects of composite T-joints.

In this study, we investigated the mechanical and energy-absorption properties of a star-shaped auxetic honeycomb under combined compression-shear loading. Novel fixtures were designed to conduct quasi-static combined compression-shear loadings. Experimental and numerical results show that the honeycomb undergoes an overall deformation based on cell rotation under quasi-static loading, producing an inclined deformation band. The normal yield stress decreased, and the shear yield stress increased with an increase in the loading angle. The extrusion deformation between meso-structures became more sufficient under dynamic combined loadings. The material deformation mode changed from overall deformation to local deformation accompanied by the formation of a shock wave. The yield criteria were established based on the ellipse equation. With an increase in the loading angle, the energy absorption in the normal and shear directions of the materials showed downward and upward trends, respectively. A theoretical model was proposed based on the 1D shock wave model to predict the energy-absorption behaviour under dynamic loading.

To further analyze the mechanical properties of random porous materials under combined loading, this paper constructs a series of random honeycomb models based on Voronoi diagrams and 3D printing. A compression-shear combined loading fixture was designed. Experiments on random honeycomb materials were conducted through the universal testing machine and the proposed fixture. The results show that reducing the cell size decreases both normal and shear stresses when relative density is consistent, while increasing the loading angle increases shear stress and decreases normal stress. Furthermore, to explore the dynamic mechanical properties, the finite element model is established. The results show that random honeycomb materials exhibit three deformation modes: random mode, transitional mode, and impact mode. Then, the sensitivity analysis of the loading angles and velocities on the yield stress is carried out. The normal stress is mainly affected by the loading velocities, and both the loading angles and velocities have significant effect on the shear stress. Finally, a phenomenological yielding criterion is established.