Plunge milling force experiment was designed based on the method of orthogonal experiment, selecting Cr12 mold steel as the experimental material for obtaining the measurement data. Combined with the experimental data, the empirical formula of the milling force model and BP neural network model were established respectively. The two types model are analyzed and compared. The results show that the BP neural network model has a better prediction effect than traditional empirical formula.
The discharge and long-term cycle behaviors of a 18650 type Li-ion batteries under different operating environments are studied through experimental tests. As temperature drops to and below -10°C, the accessible capacity of the battery is significantly decreased, which is mainly attributed to the high overpotential arising from the dramatically elevated battery internal resistance that cuts off the discharge. After comparing the cycle test results of the 18650 type batteries tested in ambient condition and at -10°C, a dramatic capacity fading was found in the battery cycled at a low temperature, which is attributed to the irreversible lithium metal formation on the anode. Furthermore, two heating approaches, forced convective heating and alternating current (AC) heating, were tested on the battery. Significant temperature non-uniformity was observed in the battery pack heated by the forced convective heating. Comparatively, the AC heating can warm the battery evenly due to the internal heating mechanism, but it took a longer time.
Battery thermal management (BTM) system is indispensable for compact lithium-ion (Li-ion) energy storage system used in aerospace and automotive applications. Besides maintaining the battery temperature within an optimum range, thus extending their lifespan and improving their electrochemical and electrical performance, the BTM system also needs to be well designed with considering the rigorous constraints imposed by the budgets in weight and volume. In this paper, a phase change material (PCM) based passive BTM system is studied. An internal cooling option is compared with the traditional external cooling design in terms of their capability in reducing the maximum temperature and improving the temperature uniformity inside battery packs with different sizes. The radial thermal conductivity of the battery is also studied regarding its effect on the thermal performance of the BTM system. Finally, the PCM usage, normalized specific energy, and space utilization ratio of the internal and external BTM systems are compared.
High speed milling hardened mould steel (above HRC50) at pocket corner generates the cutting forces increase and vibration gets fiercely because of the sudden change of cutting direction. It will cause serious wear and possible breakage of cutting tool, and poor quality of parts. Hence, the need to select reasonable cutting parameters and adopt appropriate cutting strategies will help them to achieve their goal. In this paper, the effects cutting parameters including cutting speed, pocket corner angle, feed rate per tooth and radial depth of cut on cutting force and vibration are studied. The results show that sharper pocket corner results in the increase of cutting force and makes vibration strong. Cutting force increase with the increase of cutting speeding, feed per tooth and radial depth of cut. The optimum of cutting speed leads to the decrease of vibration. It is proposed that cutting parameters should be optimized to improve tool life and processing efficiency.
Abstract The study presents a profile design method to improve the wear performance of misaligned water‐lubricated bearing based on the modified Archard model. This method takes into account the variation of the film thickness under the mixed elastohydrodynamic lubrication (mixed‐EHL). A transient hydrodynamic Reynolds equation model with the Patir–Cheng flow factors is used to predict the evolution of the mixed‐EHL performance over time. The Archard model is extended to predict the time‐varying wear based on the fatigue concept. To verify the effectiveness of the proposed profile design method; the simulation results, including the transient contact pressure, wear depth and wear volume, between the considering and not considering the profile design are compared. To gain insight, several illustrative examples are presented to show the amelioration of the profile design. Parametric studies are reported to show the applicability of the profile design and emphasise the profile height selection. Therefore, the profile design is an extraordinary method to reduce the edge wear.
At present, most of the researches on carbide surface modification are focused on the method of chemical vapor deposition and physical vapor deposition in order to enhance its wear resistance and surface hardness. In this paper, C2H2 and O2 of flame are used to deposit carbon coatings on YG 16 cemented carbide surface. The influence of deposition time have been investigated with the method of XRD, SEM. Carbon coatings structure, quality and Cross sectional microstructures of carbon coating was analyzed.The experimental result show that after different deposition time, the typical spherical diamond\nanometer carbon tube and diamond-graphite-no crystal carbon coatings have been formed on the surface of cemented carbide.
In order to study an aspherical liquid lens with simple structure and easy realization, an aspherical double-liquid lens based on planar electrode is designed based on the dielectrophoretic effect. The droplet in the dielectric electrophoretic liquid lens is polarized in the electric field and moves towards the higher electric field strength under the action of the dielectrophoresis force. With the change of the applied voltage, the dielectrophoresis force also changes, thus the contact angle of the droplet at the solid-liquid interface changes. Firstly, the models of the aspherical double-liquid lens under different voltages are established with Comsol software, and the interfacial profile data are obtained. Then the aspherical coefficients and the surface type of the fitted interface are obtained with Matlab software. Finally, the corresponding optical model of double-liquid lens is established with Zemax software. The variable range of focal lengths and root mean square (RMS) radii of the aspherical double-liquid lens at different voltages are obtained. In order to further study the characteristics of the aspherical double-liquid lens, it is compared with a spherical double-liquid lens model. Based on the contact angle theory of liquid lens and Gaussian optics theory, the relationship between the interfacial curvature radius of the spherical liquid lens and the applied voltage, and the relationship between the focal length and the applied voltage are obtained, respectively. The liquid material, cavity structure and droplet are the same as those of the aspherical lens. The corresponding spherical double-liquid lens model is established according to the two expressions relating to Zemax, and the voltage value is the same as that of the aspherical lens. Thus, the variable ranges of focal length and RMS radius in the spot diagram of the spherical double-liquid lenses at different voltages are obtained. Then, they are compared with those of aspherical double-liquid lens, and the results show that the variable range of focal length of the aspherical double-liquid lens is larger than that of the spherical double-liquid lens, and the imaging quality of the former is better than that of the latter. Moreover, through the device fabrication and preliminary experimental analysis of the aspherical double-liquid lens, the imaging resolution can reach 40.318 lp/mm. The aspherical double-liquid lens proposed in this work has the characteristics of simple structure and easy realization, which can provide a new scheme for high-quality imaging of liquid lens and its applications, and can expand the application scope of liquid lens.
'/%3e%3cuse xlink:href='%23a' transform='rotate(23.036 .093 25.536)'/%3e%3cuse xlink:href='%23a' transform='rotate(45.87 1.273 16.18)'/%3e%3cuse xlink:href='%23a' transform='rotate(69.945 .996 12.078)'/%3e%3cuse xlink:href='%23a' transform='rotate(20.66 -19.689 31.932)'/%3e%3c/svg%3e)