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Aqueous zinc batteries are promising in daily quick energy storage, but their commercialization is limited by the poor rate capability and low capacity of Zn-ion hosts, especially at practical-level mass loadings (>10 milligrams per square centimeter). This work reports a kind of aromatic organic molecular crystal, 3,4,9,10-perylenetetracarboxylic dianhydride, as an ultrahigh-rate host for Zn ions by enhancing the π–π stacking interaction to promote its ion transport kinetics. The interconnected layered structure with strong π–π stacking interaction enables fast electron transportation, and 1-D ion tunnels provide highways for rapid ion transportation. A zinc battery using such a host material displays high-rate capability (62.6% capacity remains from 1.6 C to 260.4 C), superior power density (14.8 kW kg−1) and excellent energy storage capacity reservation at high mass loading (83.6% capacity remains from 2.5 mg cm−2 to 12.3 mg cm−2), providing insight into host design for achieving ultrafast Zn-ion storage toward practical applications.

Structural analysis does not consider weld seam. Research on welding seldom pays attention to structural strength analysis. The working conditions of super large structure are complex, and the design requirements are very high. The coupled relationship between the structure of weld toe and frame stiffness in actual working conditions is analyzed to improve the accuracy of finite element model. Using the finite element method as basis, this study establishes the finite element model for the frame. The fillet joint models for the different forms of weld toe are established on the basis of thermo-elastic/plastic theory. Weld toe optimization scheme is applied to analyze frame strength. The accuracy of the model is verified by experiments. Results show that high stress appears at the connection position of the left-right longitudinal beam and rear torsion tube and the middle of rear torsion tube due to the interaction of torsion and braking. Stress between the frontal longitudinal beam and portal-type girder assembly does not significantly vary. The weld height and toe of the fillet joint are 20 mm, and the stress peak value is small. The stress distribution of the frame is analyzed by optimizing the weld toe. The stress peak value is reduced from 453.8 MPa to 340.6 MPa. Through the repair welding of the weld toe position for the optimization scheme, the welding seam surface forms a concave arc and reduces the stress concentration effectively. Failure time of the frame increases by no more than 5000 hours and does not exhibit fatigue failure. Research results are crucial for establishing coupled relationship with weld toe and frame strength and optimizing welding.

The scraper angle of milling machine has a direct effect on the milling efficiency. This research establishes the finite element model of scraper, and designs the cutting front angle and the cutting back angle as factor, impact force and the average force for orthogonal test of evaluation indexes. Through simulation analysis, the force is obtained at the different level. At the same time, the simulation results are verified by experiments. The results show that the simulation results of contact force in the X direction are close to the measured results, and prove the accuracy of the simulation results. The optimized scraper is that the cutting angle is 5.5°, and the cutting back angle is 9°. The impact force is minimum, and the resultant of average force and impact force is minimum. The optimization of scraper angle can effectively reduce the impact force and the average force, which provides guidance for the improvement of scraper.

The construction of advanced Zn-ion hybrid supercapacitors (ZHSCs) with high energy density is promising but still challenging, especially at high current densities. In this work, a high-energy and ultrastable aqueous ZHSC is demonstrated by introducing N dopants into a hierarchically porous carbon cathode for the purpose of enhancing its chemical adsorption of Zn ions. Experimental results and theoretical simulations reveal that N doping not only significantly facilitates the chemical adsorption process of Zn ions, but also greatly increases its conductivity, surface wettability, and active sites. Consequently, the as-fabricated aqueous ZHSC based on this N-doped porous carbon cathode displays an exceptionally high energy density of 107.3 Wh kg-1 at a high current density of 4.2 A g-1 , a superb power density of 24.9 kW kg-1 , and an ultralong-term lifespan (99.7% retention after 20 000 cycles), substantially superior to state-of-the-art ZHSCs. Particularly, such a cathode also leads to a quasi-solid-state device with satisfactory energy storage performance, delivering a remarkable energy density of 91.8 Wh kg-1 . The boosted energy storage strategy by tuning the chemical adsorption capability is also applicable to other carbon materials.

To verify the correctness of the sample quality and the finite element model, optical measurement technology is applied in this study. Unable to consider the quality of tack welding during the established modeling, a three-dimensional scanner is used to detect box complex structures after welding. The finite element model of box structure is established for the study of welding deformation of box structure with short, multi space and multi staggered distributed weld seam. The accuracy of the model is verified by global detection of the structural parts. The results show that the deformation trend warps at the boundary of the left and right plate and concaves in the center of the plate. The maximum deformation of the vertical plate center is 1.714mm. The bottom pad produces the extruding tendency, and the deformation near two sides of the plate is about 0.51mm, which is greater than that of 0.34mm away from the two sides of the plate. The deformation is not consistent in the front and back sides of the Z plate. The maximum error of the sample parts takes place in the front Z shape plate with an error of - 0.03mm~0.12mm. There is a certain size difference under the influence of the welding gap, but it still meets the requirements of the engineering application to eliminate the influence of the welding quality on the deformation measurement. By comparing the results of the simulation and the global measurement of the structural parts, the difference between the vibration seat and the front Z plate has a large difference that is 0.12mm∼0.24mm, and the deviation satisfies the requirements of the engineering application, and it can effectively guide the production.

To explore the influence of mesh size on the accuracy of welding simulation, the weld seam and heat affected zone are treated with different mesh sizes. The finite element models are established to obtain the welding deformation and residual stress distribution of the lap joint. The results are verified by the test. The results show that, from the trend of deformation and residual stress distribution, results from different weld mesh sizes coincide with the distribution trend of test results, which proves the validity of the finite element models. Welding deformation of the starting arc position is less than that of the ending arc welding position, and the maximum deformation position occurs on the free side along the longitudinal end of weld seam. The change of mesh size has a certain effect on the residual stress distribution. By comparing with the test results, the errors of mesh size of 0.5mm, 1mm, 2mm and 3mm are 2.4%, 5.1%, 16.6% and 12% respectively. The research results have important guiding significance for the pre-processing of welding simulation.

For roll-over protective structures (ROPS) in a mechanical driving dump truck cab, it simulates the lateral, vertical and longitudinal loads of ROPS. It obtains stress and deformation of the cab that occurs to roll. For the relative weak position of ROPS in the cab, the structure of the cab is improved and verified according to the ISO 3164: 1995. The results show that the established finite element model can effectively predict the deformation and stress distribution of ROPS, and optimize the weak structure of the cab, which has important guiding significance for structural design of the cab and ROPS optimization of the mechanical driving dump truck cab.

To effectively enhance the service life, the research of milling machine scraper structure design and welding process are optimized. Through the structural optimization analysis, the improved structure is obtained, and the working resistance force is reduced. The full factor test is used to optimize the brazing process, and the best parameters are obtained, which improves the shear strength. The accuracy of the model is verified by experiments. The results show that compared with the working resistance force, the improved scraper tends to be slow and the peak value is smaller. The cutting rake and relief angle of the scraper are optimized. When the cutting rake angle is 6° and the cutting relief angle is 9°, both working resistance force and impact force are minimum. It proves the accuracy of the simulation results. Using CT861 solder, brazing temperature is 75°C, and the brazing time is 10s. While the cooling method uses furnace cold, the minimum value of shear strength is 200MPa. The average working life of the scraper is raised from 800 hours to 1600 hours after the optimization design. Research results have guiding significance for the structure design and the welding process optimization of the scraper.